DPS complex

A protein serine/threonine phosphatase complex that in S. pombe consists of the proteins Dis2, Ppn1, and Swd22.


Wnt signalosome

biolink:CellularComponent biolink:AnatomicalEntity biolink:OrganismalEntity biolink:BiologicalEntity biolink:NamedThing biolink:PhysicalEssence biolink:SubjectOfInvestigation biolink:ThingWithTaxon biolink:PhysicalEssenceOrOccurrent

A multiprotein protein complex containing membrane-localized Wnt receptors and cytosolic protein complexes, which is capable of transmitting the Wnt signal. Contains at least a Wnt protein, LRP5 or LRP6, a member of the Frizzled (Fz) family, Axin and and a Dishevelled (DVL) protein.


PUMA-BCL-2 complex

A heterodimeric protein complex consisting of PUMA and BCL-2, members of the Bcl-2 family of anti- and proapoptotic regulators.


Lsm-containing SMN-Sm protein complex

An SMN-Sm protein complex formed by the association of the methylated Sm proteins B/B', D3, E, F, and G, and Lsm10 and Lsm11, with the SMN complex. This complex forms Sm cores on U7 snRNA.


Bcl3-Bcl10 complex

A protein complex containing Bcl3 and Bcl10, which forms when Akt1 is activated by TNF-alpha to phosphorylate Bcl10; the Bcl3-Bcl10 complex is translocated to the nucleus.


DNA recombinase complex

A protein-DNA complex consisting of a higher-order oligomer of strand exchange proteins (recombinases) on single-stranded DNA.


MCM complex

A hexameric protein complex required for the initiation and regulation of DNA replication.


PSI associated light-harvesting complex I, LHCIa subcomplex

A pigment protein complex that forms part of the photosystem I associated light-harvesting complex I; contains two proteins (usually about 24 and 21.5 kDa); has a fluorescence maximum between 680 and 690 nm.


laminin-522 complex

A laminin complex composed of alpha5, beta2 and gamma2 polypeptide chains.


Seh1-associated complex

A GTPase-activating protein (GAP) complex that regulates TORC1 signaling by interacting with the Rag GTPase. In S. cerevisiae the complex contains Seh1p, Sec13p, Npr2p, Npr3p, Iml1p, Mtc5p, Rtc1p, and Sea4p.


DiaA complex

A homotetrameric protein complex consisting of a symmetrical pair of DiaA homodimers. Facilitates DnaA binding to the origin of replication during replication initiation.


trans-synaptic protein complex

A protein complex that spans the synaptic cleft and has parts in both the pre- and post-synaptic membranes.


exomer complex

A protein complex that forms a coat structure on vesicles involved in exocytosis of proteins from the trans-Golgi network to the cell surface; in Saccharomyces, the complex contains Chs5p, Chs6p, and Chs6p paralogues.


cobalamin transport complex

Protein complex facilitating ATP-dependent cobalamin (vitamin B12) transport through inner cell membrane (periplasm to cytoplasm) in Gram-negative bacteria. In E. coli the system is composed of a periplasmic cobalamin-binding protein (BtuF), an integral membrane homodimer, BtuC, and a cytoplasmic ATP-binding homodimer BtuD.


MAML3-RBP-Jkappa-ICN4 complex

A protein complex that consists of the intracellular domain of Notch4 (ICN4), the DNA-binding transcription factor RBP-Jkappa, and the transcriptional coactivator Mastermind-like-3 (MAML3); the complex is involved in transcriptional activation in response to Notch-mediated signaling.


methyl-tetrahydromethanopterin:coenzyme M methyltransferase complex

A protein complex consisted of eight polypeptides. This complex catalyzes the formation of methyl-coenzyme M and H4MPT from N5-methyl-H4MPT and CoM during methanogenesis.


cytosolic aryl hydrocarbon receptor complex

An aryl hydrocarbon receptor complex found in the cytosol, in which the ligand-binding subunit AhR is not bound to ligand; consists of AhR, two molecules of HSP90, the protein kinase c-Src, and the immunophilin XAP2/AIP.


glutamate-tRNA ligase complex

An enzyme complex that catalyzes the ligation of glutamate and tRNA(Glu) to form glutamyl-tRNA(Glu).


radial spoke base

The short portion of the radial spoke that is directly anchored to the A microtubule of an axonemal microtubule doublet.


interleukin-4 receptor complex

A protein complex that binds interleukin-4 (IL-4) and consists of an alpha chain that binds IL-4 with high affinity and a gamma common chain that also forms part of the interleukin-2 receptor.


iron-sulfur cluster transfer complex

A protein complex capable of catalyzing the transfer of an iron-sulfur (Fe-S) cluster from one compound (donor) to another (acceptor).


photosystem I reaction center

A photochemical system containing P700, the chlorophyll a dimer that functions as a primary electron donor. Functioning as a light-dependent plastocyanin-ferredoxin oxidoreductase, it transfers electrons from plastocyanin to ferredoxin.


fatty-acyl-CoA synthase complex

A protein complex that possesses fatty-acyl-CoA synthase activity.


BORC complex

A protein complex that is involved in positioning of the lysosome within the cytoplasm and which is composed of BLOC1S1, BLOC1S2, BORCS5, BORCS6, BORCS7, BORCS8, KXD1 and SNAPIN. The BORC complex recruits ARL8 at the cytosolic face of lysosomes and couples them to microtubule plus-end-directed kinesin motors.


B800-850 antenna complex

Protein-pigment complex that absorbs light at 800 and 850 nm; is peripherally associated to the bacterial reaction center; transfers excitation energy to the B875 antenna complex.


exoribonuclease complex

A protein complex which is capable of exoribonuclease activity.


glycine-tRNA ligase complex

A multimeric enzyme complex which, in bacteria, is usually a tetramer of two alpha and two beta chains and in eukaryotes, is usually a homodimer. Functions in the ligation of glycine and tRNA(Gly) to form glycyl-tRNA(Gly).


7SK snRNP

A ribonucleoprotein complex that contains the 7SK snRNA. The 7SK snRNP plays a central role in RNA polymerase II elongation control by regulating the availability of active P-TEFb.


TRAMP complex

A multiprotein complex having distributive polyadenylation activity of a variety of RNA substrates including hypomodified and incorrectly folded tRNAs, pre-snRNAs, pre-snoRNAs, incorrectly spliced or processed pre-mRNAs, cryptic unstable transcripts (CUTs), pre-rRNAs and rRNA fragments released as part of rRNA processing. In S. cerevisiae, the complex consists of either Pap2 (also known as Trf4) or Trf5, Air1 or Air2, and Mtr4, and is involved in RNA 3'-end processing and in RNA surveillance and quality control.


fumarate reductase complex

A membrane-bound flavoenzyme complex consisting of four subunits, A, B, C, and D. A and B comprise the membrane-extrinsic catalytic domain and C (InterPro:IPR003510; InterPro:IPR004224) and D (InterPro:IPR003418) link the catalytic centers to the electron-transport chain. This family consists of the 13 kDa hydrophobic subunit D. This component may be required to anchor the catalytic components of the fumarate reductase complex to the cytoplasmic membrane. Fumarate reductase couples the reduction of fumarate to succinate to the oxidation of quinol to quinone, in a reaction opposite to that catalyzed by the related complex II of the respiratory chain (succinate dehydrogenase-(ubiquinone)).


Pip2-Oaf1 complex

A heterodimeric complex consisting of Zn(2)Cys(6) containing transcription factors Pip2 and Oaf1. It binds to the oleate response element (ORE), found in the promoters of fatty acid-inducible genes in Saccharomyces where, in the presence of oleate this bound complex activates the transcription of genes encoding peroxisomal proteins.


RasGAP-Fyn-Lyn-Yes complex

A protein complex that consists of a GTPase activator protein (GAP) for Ras and three Src family protein tyrosine kinases, Fyn, Lyn and Yes. The complex is involved in signaling upon platelet activation.


A protein complex that consists of an alphaV-beta6 integrin complex bound to osteopontin.


GATOR1 complex

A GTPase-activating protein (GAP) complex that regulates TORC1 signaling by interacting with the Rag GTPase. In human, the GATOR1 complex consists of DEPDC5, NPRL2, and NPRL3. In S. cerevisiae, this complex is referred to as SEACIT and contains the Iml1p, Npr2p, and Npr3p proteins.


alpha-beta T cell receptor complex

A T cell receptor complex in which the TCR heterodimer comprises alpha and beta chains, associated with the CD3 complex; recognizes a complex consisting of an antigen-derived peptide bound to a class I or class II MHC protein.


E.F.G complex

A protein complex that comprises three core spliceosomal proteins, designated E, F, and G. Formation of the E.F.G complex is essential but not sufficient for the formation of a stable U1 snRNP complex.


nuclear pore linkers

A substructure of the nuclear pore complex (NPC) that serves to connect members of the central transport channel (composed of FG-nucleoporins) to the core scaffold (composed of the inner and outer NPC rings). In S. cerevisiae, the linkers are Nic96p and Nup82p. In vertebrates, they are Nup93 and Nup88. Components are arranged in 8-fold symmetrical 'spokes' around the central transport channel. Both linkers can be isolated in association with specific FG-nucleoporins, complexes that are sometimes referred to as the Nic96 complex (Nic96p-Nsp1p-Nup49p-Nup57p) and the Nup82 complex (Nup82p-Nup116p-Nup159p-Gle2p).


RNA polymerase I transcription regulator complex

A transcription factor complex that acts at a regulatory region of a gene transcribed by RNA polymerase I.


APC-IQGAP1-CLIP-170 complex

A protein complex that contains the tumor suppressor protein adenomatous polyposis coli (APC), the small GTPase Cdc42, and CLIP-170; may play a role in cytoskeleton organization and cell migration.


clathrin coat

A membrane coat found on coated pits and some coated vesicles; consists of polymerized clathrin triskelions, each comprising three clathrin heavy chains and three clathrin light chains, linked to the membrane via one of the AP adaptor complexes.


type IV site-specific deoxyribonuclease complex

A complex consisting of two proteins which acts as an endonuclease in DNA sequences containing a specific modified recognition site. Modifications may include methylation, hydroxymethylation, and glucosyl-hydroxymethylation.


collagen type XIV trimer

A collagen homotrimer of alpha1(XIV) chains; type XIV collagen triple helices may link sheet-forming or fibrillar collagens to other structures.


EMC complex

A transmembrane protein complex located in the endoplasmic reticulum (ER) involved in the insertion of newly synthesized proteins in the membrane of the ER. In S. cerevisiae, it has six members: EMC1, EMC2, AIM27, EMC4, KRE27, and EMC6.


Fanconi anaemia nuclear complex

A protein complex composed of the Fanconi anaemia (FA) proteins including A, C, E, G and F (FANCA-F). Functions in the activation of the downstream protein FANCD2 by monoubiquitylation, and is essential for protection against chromosome breakage.


heavy chain immunoglobulin complex

A protein complex composed of two identical immunoglobulin heavy chains of the IgNAR isotype held together by disulfide bonds and lacking immunoglobulin light chains.


alpha5-beta1 integrin-tissue transglutaminase complex

A protein complex that consists of an alpha5-beta1 integrin complex bound to tissue transglutaminase.


alpha6-beta4 integrin-CD151 complex

A protein complex that consists of an alpha6-beta4 integrin complex bound to the tetraspanin CD151.


IgD B cell receptor complex

An IgD immunoglobulin complex that is present in the plasma membrane of B cells and is composed of two identical immunoglobulin heavy chains of the IgD isotype and two identical immunoglobulin light chains and a signaling subunit, a heterodimer of the Ig-alpha and Ig-beta proteins.


replication inhibiting complex

A protein complex that inhibits multiple events of replication initiation during one replication cycle.


polyketide synthase complex

A protein complex that carries out enzymatic reactions involved in the biosynthesis of polyketides, any of a diverse group of natural products synthesized via linear poly-beta-ketones.


interleukin-12 receptor complex

A protein complex that binds interleukin-12 and that consists of, at a minimum, a dimeric interleukin and its two receptor subunits as well as optional additional kinase subunits.


Grb2-SHP-2 complex

A protein complex that contains the receptor adaptor proteins Grb2 and SHP-2, and is involved signaling via the PDGFR signaling pathway.


CFTR-NHERF-ezrin complex

A protein complex that contains ezrin, Na+/H+ exchanger regulatory factor (NHERF, also called EBP50), and two copies of the cystic fibrosis transmembrane conductance regulator (CFTR). The CFTR molecules interact with NHERF via their cytoplasmic tail domains; the complex is thought to link the CFTR channel to the actin cytoskeleton and contribute to the regulation of channel activity.


eNoSc complex

A chromatin silencing complex that recruits histone-modifying enzymes and upregulates silencing of rDNA in response to glucose starvation.


Mre11 complex

Trimeric protein complex that possesses endonuclease activity; involved in meiotic recombination, DNA repair and checkpoint signaling. In Saccharomyces cerevisiae, the complex comprises Mre11p, Rad50p, and Xrs2p; complexes identified in other species generally contain proteins orthologous to the Saccharomyces cerevisiae proteins.


CSK-GAP-A.p62 complex

A protein complex that contains the protein-tyrosine kinase CSK and the GTPase-activating protein (GAP)-associated p62 (GAP-A.p62); may mediate translocation of proteins, including GAP and CSK, to membrane or cytoskeletal regions upon c-Src activation.


cytosolic tricarboxylic acid cycle enzyme complex

Any of the heteromeric enzymes, located in the cytosol, that act in the tricarboxylic acid (TCA) cycle.


NLRP6 inflammasome complex

An inflammasome complex that consists of NLRP6, PYCARD/ASC and caspase-1 or caspase-4/caspase-11.


Smc5-Smc6 complex

A conserved complex that contains a heterodimer of SMC proteins (Smc5p and Smc6p, or homologs thereof) and several other proteins, and is involved in DNA repair and maintaining cell cycle arrest following DNA damage. In S. cerevisiae, this is an octameric complex called Mms21-Smc5-Smc6 complex, with at least five of its subunits conserved in fission yeast and humans.


TRAPP complex

A large complex that acts as a tethering factor involved in transporting vesicles from the ER through the Golgi to the plasma membrane. A TRAPP (transport protein particle) complex has a core set of proteins which are joined by specific subunits depending on the cellular component where a given TRAPP complex is active.


Sodium:potassium-exchanging ATPases are tetrameric proteins, consisting of two large alpha subunits and two smaller beta subunits. The alpha subunits bear the active site and penetrate the membrane, while the beta subunits carry oligosaccharide groups and face the cell exterior.


cortical Lewy body

Cytoplasmic inclusion similar to a classical Lewy body but lacking a halo of protein fibrils.


inclusion body

A discrete intracellular part formed of aggregated molecules such as proteins or other biopolymers.


nucleolar peripheral inclusion body

Inclusion bodies located at the nucleolar periphery where several nuclear factors are reversibly aggregated and sequestered during acute heat stress or starvation.


classical Lewy body

Cytoplasmic inclusion, 5 to 15 micrometers in diameter, with a dense core surrounded by a halo of 10 to 20 nm wide radially oriented alpha-synuclein fibrils.


nematosome

Cytoplasmic, ball-like inclusion resembling a nucleolus and consisting of a convoluted network of electron-opaque strands embedded in a less dense matrix. It measures approximately 0.9 microns and lacks a limiting membrane. Its strands (diameter = 400-600 A) appear to be made of an entanglement of tightly packed filaments and particles approximately 25-50 A thick. Cytochemical studies suggest the presence of nonhistone proteins and some RNA. Usually only one such structure is present in a cell, and it appears to occur in most ganglion cells. Although they can be seen anywhere in the cell body, nematosomes are typically located in the perinuclear cytoplasm, where they are often associated with smooth-surfaced and coated vesicles.


skein-like inclusion

Intracytoplasmic filamentous structure frequently encountered in preparations immunostained for ubiquitin.


aggresome

An inclusion body formed by dynein-dependent retrograde transport of an aggregated protein on microtubules.


fibrillary inclusion

Cellular inclusion consisting of circular areas filled with fine slender filaments about 10 nanometers in diameter, delimited by a wall of varying complexity (either a single continuous membrane or a tubular network consisting of a fine filamentous material giving the wall a honeycomb appearance). Fibrillary inclusions are found in the cytoplasm of giant cells of Dieters in the lateral vestibular nucleus of the rat; similar structures have been described in the ventral cochlear nucleus, spinal cord, and substantia nigra.


neurofibrillary tangle

Intracellular mass of paired, helically wound protein filaments (also called PHF) lying in the cytoplasm of neuronal cell bodies and neuritic cell processes. Neurofibrillary tangles contain an abnormally phosphorylated form of a microtubule-associated protein, tau. The shape of these inclusions may resemble a flame or a star.


nuclear inclusion body

An intranuclear focus at which aggregated proteins have been sequestered.


glial cytoplasmic inclusion

Non-membrane-bound cytoplasmic inclusions composed of 10-40 nm granule-coated fibrils. These inclusions have an abnormal accumulation of alpha-synuclein protein and are found in association with multiple system atrophy.


Lewy body

Cytoplasmic, spherical inclusion commonly found in damaged neurons, and composed of abnormally phosphorylated, neurofilament proteins aggregated with ubiquitin and alpha-synuclein.


complex laminated body

A cytoplasmic inclusion body found in some lateral geniculate neurons and composed of sheets of tubules (25 nm in diameter) separated by dense material (about 75 nm wide), which together with the tubules whorl give a structure resembling a fingerprint.


laminated body

Inclusion body characterized by regularly spaced sheets of tubules arranged in a whorl pattern resembling a fingerprint. Laminated bodies have been observed in neurons of the lateral geniculate nucleus.


Pick body

Cellular inclusion composed of numerous tau fibrils arranged in a disorderly array. Tau protein is a major component, though Pick bodies also contain ubiquitin, alpha-synuclein, and apolipoprotein E.


hyaline inclusion

A glass-like, pale intracellular inclusion.


fibrillar center

A structure found most metazoan nucleoli, but not usually found in lower eukaryotes; surrounded by the dense fibrillar component; the zone of transcription from multiple copies of the pre-rRNA genes is in the border region between these two structures.


cnida

A giant secretory organelle that comprises a bulb-shape capsule containing a coiled hollow tubule structure attached to it. A cnida defines the phylum Cnidaria.


glutamatergic postsynaptic density

The post-synaptic specialization of a glutamatergic excitatory synapse.


presynaptic active zone membrane

The membrane portion of the presynaptic active zone; it is the site where docking and fusion of synaptic vesicles occurs for the release of neurotransmitters.


central plaque of mitotic spindle pole body

One of three laminate structures that form the mitotic spindle pole body; the inner plaque is on the nuclear face of the spindle pole body.


central plaque of spindle pole body

One of three laminate structures that form the spindle pole body; the central plaque is embedded in the nuclear envelope.


central region of growth cone

The center of the migrating motile tip of a growing nerve cell axon or dendrite.


cellular bud neck contractile ring

A contractile ring, i.e. a cytoskeletal structure composed of actin filaments and myosin, that forms beneath the plasma membrane at the mother-bud neck in mitotic cells that divide by budding in preparation for completing cytokinesis. An example of this structure is found in Saccharomyces cerevisiae.


extrahaustorial matrix

The space between the symbiont plasma membrane and the extrahaustorial membrane of the host.


glyoxysomal membrane

The lipid bilayer surrounding a glyoxysome.


glycosome membrane

The lipid bilayer surrounding a glycosome.


nucleus lagging edge

The area of a motile nucleus furthest from the direction of movement.


bleb

A cell extension caused by localized decoupling of the cytoskeleton from the plasma membrane and characterized by rapid formation, rounded shape, and scarcity of organelles within the protrusion. Blebs are formed during apoptosis and other cellular processes, including cell locomotion, cell division, and as a result of physical or chemical stresses.


mannosome

A specialised tubular organelle, assembled in hexagonal bundles within an external membrane. Mannosomes are specific to molluscs and are thought to be involved in a general stress reaction.


trans-Golgi network membrane

The lipid bilayer surrounding any of the compartments that make up the trans-Golgi network.


ribbon synapse

Type of synapse characterized by an electron-dense ribbon, lamella (bar) or spherical body in the presynaptic process cytoplasm.


photoreceptor ribbon synapse

A ribbon synapse between a retinal photoreceptor cell (rod or cone) and a retinal bipolar cell. These contain a plate-like synaptic ribbon.


cochlear hair cell ribbon synapse

A ribbon synpase of an auditory hair cell of the cochlear. These ribbon synapses contain spherical synaptic ribbons and lack and arciform density.


extrinsic component of postsynaptic membrane

The component of the postsynaptic membrane consisting of gene products and protein complexes that are loosely bound to one of its surfaces, but not integrated into the hydrophobic region.


extrinsic component of presynaptic membrane

The component of the presynaptic membrane consisting of gene products and protein complexes that are loosely bound to one of its surfaces, but not integrated into the hydrophobic region.


extrinsic component of presynaptic endocytic zone membrane

The component of the presynaptic endocytic zone membrane consisting of gene products and protein complexes that are loosely bound to one of its surfaces, but not integrated into the hydrophobic region.


extrinsic component of postsynaptic specialization membrane

The component of the postsynaptic specialization membrane consisting of gene products and protein complexes that are loosely bound to one of its surfaces, but not integrated into the hydrophobic region.


extrinsic component of postsynaptic density membrane

The component of the postsynaptic density membrane consisting of gene products and protein complexes that are loosely bound to one of its surfaces, but not integrated into the hydrophobic region.


extrinsic component of external side of plasma membrane

The component of a plasma membrane consisting of gene products and protein complexes that are loosely bound to its external surface, but not integrated into the hydrophobic region.


extrinsic component of presynaptic active zone membrane

The component of the presynaptic active zone membrane consisting of gene products and protein complexes that are loosely bound to one of its surfaces, but not integrated into the hydrophobic region.


extrinsic component of synaptic membrane

The component of the synaptic membrane consisting of gene products and protein complexes that are loosely bound to one of its surfaces, but not integrated into the hydrophobic region.


extrinsic component of postsynaptic endocytic zone

The component of the postsynaptic endocytic zone membrane consisting of gene products and protein complexes that are loosely bound to one of its surfaces, but not integrated into the hydrophobic region.


bacterial microcompartment

An organelle found in bacteria consisting of a proteinaceous coat containing metabolic enzymes whose purpose is the sequestration or concentration of metabolites and which has the appearance of a polygonal granule by electron microscopy.


perinucleolar chromocenter

A chromocenter adjacent to the nucleolus.


condensed nuclear chromosome

A highly compacted molecule of DNA and associated proteins resulting in a cytologically distinct nuclear chromosome.


meiotic spindle

A spindle that forms as part of meiosis. Several proteins, such as budding yeast Spo21p, fission yeast Spo2 and Spo13, and C. elegans mei-1, localize specifically to the meiotic spindle and are absent from the mitotic spindle.


mitochondrial nucleoid

The region of a mitochondrion to which the DNA is confined.


protein aggregate center

Reversible aggregate of misfolded proteins and chaperones formed to shield thermosensitive proteins from degradation until conditions allow disaggregation and refolding.


crystalloid

A transient, cytoplasmic organelle found in Plasmodium species that resembles a cytoplasmic inclusion body and whose function is poorly understood. Crystalloids form in ookinetes and disappear after ookinete-to-oocyst transformation.


cytosolic ribosome

A ribosome located in the cytosol.


arciform density

An electron dense structure that anchors a synaptic ribbon to the presynaptic membrane.


monolayer-surrounded lipid storage body

A subcellular organelle of plant cells surrounded by 'half-unit' or a monolayer membrane instead of the more usual bilayer. The storage body has a droplet of triglyceride surrounded by a monolayer of phospholipids, interacting with the triglycerides and the hydrophilic head groups facing the cytosol, and containing major protein components called oleosins.


mitochondrial chromosome

A chromosome found in the mitochondrion of a eukaryotic cell.


Z chromosome

The sex chromosome present in both sexes of species in which the female is the heterogametic sex. Two copies of the Z chromosome are present in each somatic cell of males and one copy is present in females.


spectrosome

A germline specific spherical organelle, rich in membrane skeletal proteins. Precursor to the fusome.


spindle

The array of microtubules and associated molecules that forms between opposite poles of a eukaryotic cell during mitosis or meiosis and serves to move the duplicated chromosomes apart.


sex chromosome

A chromosome involved in sex determination.


ascus lipid droplet

Any particle of coalesced lipids in an ascus or ascospore. May include associated proteins.


Barr body

A structure found in a female mammalian cell containing an unpaired X chromosome that has become densely heterochromatic, silenced and localized at the nuclear periphery.


chloroplast nucleoid

The region of a chloroplast to which the DNA is confined.


chloroplast stromal thylakoid

Unstacked thylakoids that connect the grana stacks through the stroma.


plastid ribosome

A ribosome contained within a plastid.


XY body

A structure found in a male mammalian spermatocyte containing an unpaired X chromosome that has become densely heterochromatic, silenced and localized at the nuclear periphery.


pyrenoid

A non-membrane-bounded organelle found within the chloroplasts of algae and hornworts; responsible for carbon dioxide fixation.


carboxysome

An organelle consisting of a proteinaceous coat and enzymes for the fixation of CO2. It augments the concentration of CO2 in the vicinity of RuBisCO to increase the efficiency of CO2 fixation under atmospheric conditions.


bacterial nucleoid

The region of a bacterial cell to which the DNA is confined.


goblet cell theca

A cup shaped specialization of the cytoskeleton that forms a thin layer located just below the apical mass of mature mucin secretory granules in the cytoplasm of goblet cells of the intestinal epithelium. It consists of an orderly network of intermediate filaments and microtubules. Microtubules are arranged vertically, like barrel staves, along the inner aspect of the theta. Intermediate filaments form two networks: an inner, basketlike network and an outer series of circumferential bundles resembling the hoops of a barrel.


synaptic ribbon

A non-membrane bound, electron dense structure associated that extends perpendicular to the presynaptic membrane in ribbon synapses. The ribbon's surface is studded with small particles to which synaptic vesicles tether via fine filaments. The tethered vesicles function as a pool, several fold greater than the docked pool available for fast release, which supports sustained release of vesicles. Synaptic ribbons may be plate like or spherical.


proplastid nucleoid

The region of a proplastid to which the DNA is confined.


Y chromosome

The sex chromosome present in males of species in which the male is the heterogametic sex; generally, the sex chromosome that pairs with the X chromosome in the heterogametic sex. The Y chromosome is absent from the cells of females and present in one copy in the somatic cells of males.


active sex chromosome

A sex chromosome that has not been inactivated.


polytene chromosome chromocenter

A region at which the centric regions of polytene chromosomes are joined together.


cyanelle thylakoid

A thylakoid found in a cyanelle, which is a type of plastid found in certain algae. The cyanelle contains a photosynthetic membrane resembling that of cyanobacteria.


organellar ribosome

A ribosome contained within a subcellular membrane-bounded organelle.


prothylakoid

Underdeveloped thylakoids found in etioplasts, lacking competent photosynthetic membranes. Rapidly develop into mature thylakoids in the presence of light.


bacterial thylakoid

A thylakoid that is derived from and attached to, but not necessarily continuous with, the plasma membrane, and is not enclosed in a plastid. It bears the photosynthetic pigments in photosynthetic cyanobacteria.


gas vesicle

An intracellular non-membrane-bounded organelle; a hollow structure made of protein, which usually has the form of a cylindrical tube closed by conical end caps. By regulating their relative gas vesicle content, aquatic microbes are able to perform vertical migrations.


nucleolus-like body

A nuclear compartment containing significant amounts of non-nucleolar, spliceosomal components. It is commonly found in germinal vesicle (GV) stage oocytes, and is similar to both nucleoli and sphere organelles.


dynein axonemal particle

An aggregation of axonemal dyneins, their specific assembly factors, and broadly-acting chaperones that is located in the cytoplasm.


autosome

Any chromosome other than a sex chromosome.


organellar chromatophore thylakoid

A thylakoid located in an organellar chromatophore.


plastid thylakoid

Any thylakoid within a plastid.


plastid nucleoid

The region of a plastid to which the DNA is confined.


propanediol degradation polyhedral organelle

An organelle found in bacteria consisting of a proteinaceous coat containing enzymes for the degradation of 1,2-propanediol whose purpose is the protection of the rest of the cell from the toxic propionaldehyde product of the enzyme diol dehydratase.


chlorosome

A large enclosure of aggregated pigment, typically bacteriochlorophyll c (BChl c), that acts as a light-harvesting antenna structure and is characteristic of green photosynthetic bacteria (e.g. Chlorobiaceae). The BChl aggregates are organized into lamellar elements by pigment-pigment rather than pigment-protein interactions. Chlorosomes also contain BChl a, carotenoids, quinones, lipids, and proteins, and are attached to the cytoplasmic membrane via a BChl a-containing protein baseplate.


nuclear chromosome

A chromosome that encodes the nuclear genome and is found in the nucleus of a eukaryotic cell during the cell cycle phases when the nucleus is intact.


ventral disc

Specialized organelle found in Giardia species (trophozoite stage) and characterized by a spiral array of microtubules and microtubule-associated structures including dorsal microribbons and crossbridges. The edge of the ventral disc narrows into a lateral crest. The ventral disk mediates mechanical attachment of the trophozoite to the host's intestinal wall, and contains the contractile proteins actinin, alpha-actinin, myosin, and tropomyosin working towards contraction of the disk involved in adherence.


nematocyst

An organelle found in cnidoblast (nematoblast) cells. When matured, these stinging organelles store toxins and can deliver them when the cnidocil (a short extension of the cnidocyst) is stimulated by a prey or another stimulus.


W chromosome

The sex chromosome present in females of species in which the female is the heterogametic sex; generally, the sex chromosome that pairs with the Z chromosome in the heterogametic sex. The W chromosome is absent from the cells of males and present in one copy in the somatic cells of females.


inactive sex chromosome

A sex chromosome that has been inactivated.


X chromosome

The sex chromosome present in both sexes of species in which the male is the heterogametic sex. Two copies of the X chromosome are present in each somatic cell of females and one copy is present in males.


blepharoplast

An intracellular non-membrane-bounded organelle found in multi-ciliated sperm cells of some primitive land plants, and consisting of many radially arranged ninefold symmetric cylinders. The blepharoplast is involved in de novo formation of multiple centrioles; it enlarges and then disintegrates into many procentrioles, which elongate and ultimately nucleate cilia on the surface of the sperm cell.


granal stacked thylakoid

Appressed thylakoid membranes that are part of a granum (stacked regions). A characteristic of these appressed regions is the preferential localization of photosystem II.


mitochondrial ribosome

A ribosome found in the mitochondrion of a eukaryotic cell; contains a characteristic set of proteins distinct from those of cytosolic ribosomes.


chromocenter

A region in which centric, heterochromatic portions from more than one chromosomes form a compact structure.


podosome

An actin-rich adhesion structure characterized by formation upon cell substrate contact and localization at the substrate-attached part of the cell, contain an F-actin-rich core surrounded by a ring structure containing proteins such as vinculin and talin, and have a diameter of 0.5 mm.


proteasome storage granule

An aggregation of proteasome core protease (CP) and regulatory particle (RP) complexes that localizes in the cytoplasm as dot-like structures when cells are in a quiescent state.


elaioplast

A leucoplast in which oil is stored.


histone locus body

A nuclear body associated with the histone gene locus that is thought to contain all of the factors necessary for histone mRNA transcription and pre-mRNA processing. In Drosophila, U7 snRNP is located in the histone locus body rather than the distinct Cajal body.


mitotic nuclear bridge

A narrow constricted region of the nucleus that forms around the anaphase spindle during closed mitosis, and connects the main portions of the newly forming daughter nuclei.


amphisome membrane

Any membrane that is part of an amphisome.


extrinsic component of external side of mycolate outer membrane

The component of mycolate membrane consisting of gene products and protein complexes that are loosely bound to its external surface, but not integrated into the hydrophobic region.


extrinsic component of mycolate outer membrane

The component of mycolate outer membrane consisting of gene products and protein complexes that are loosely bound to one of its surfaces, but not integrated into the hydrophobic region.


alae of collagen and cuticulin-based cuticle extracellular matrix

Raised, thickened cuticular ridges that run longitudinally, and in parallel, along the left and right sides of the animal. The alae lie above the hypodermal cells known as the lateral seam cells. In C. elegans, alae are produced in L1 larvae, dauer larvae and adult stage animals, where they consist of three, five, and three ridges of distinct morphology, respectively.


pnictogen molecular entity

A p-block molecular entity containing any pnictogen.


peptide

Amide derived from two or more amino carboxylic acid molecules (the same or different) by formation of a covalent bond from the carbonyl carbon of one to the nitrogen atom of another with formal loss of water. The term is usually applied to structures formed from alpha-amino acids, but it includes those derived from any amino carboxylic acid. X = OH, OR, NH2, NHR, etc.


primary amide

A derivative of an oxoacid RkE(=O)l(OH)m (l =/= 0) in which an acidic hydroxy group has been replaced by an amino or substituted amino group.


amide

An amide is a derivative of an oxoacid RkE(=O)l(OH)m (l =/= 0) in which an acidic hydroxy group has been replaced by an amino or substituted amino group.


carboxamide

An amide of a carboxylic acid, having the structure RC(=O)NR2. The term is used as a suffix in systematic name formation to denote the -C(=O)NH2 group including its carbon atom.


organonitrogen compound

Any heteroorganic entity containing at least one carbon-nitrogen bond.


organic amino compound

A compound formally derived from ammonia by replacing one, two or three hydrogen atoms by organyl groups.


host cell late endosome

A prelysosomal endocytic organelle differentiated from host early endosomes by lower lumenal pH and different protein composition. Host late endosomes are more spherical than early endosomes and are mostly juxtanuclear, being concentrated near the microtubule organizing center.


polar tube

A highly specialized structure unique to microsporidia that is required for host cell invasion. In the spore, the polar tube is connected at the anterior end, and then coils around the sporoplasm. Upon appropriate environmental stimulation, the polar tube rapidly discharges out of the spore, pierces a cell membrane and serves as a conduit for sporoplasm passage into the new host cell.


endospore coat

The layer in a bacterial endospore that lies under the exosporium, and is impermeable to many toxic molecules. The coat may also contain enzymes that are involved in endospore germination.


Yb body

A cytoplasmic part that appears as an electron-dense sphere of around 1.5 micron diameter containing Yb protein found in somatic cells of ovary and testis. There are one to two Yb bodies per cell.


leucoplast stroma

The space enclosed by the double membrane of a leucoplast.


linear element

A proteinaceous scaffold associated with fission yeast chromosomes during meiotic prophase. Linear elements consist of a protein complex, LinE, with four main structural components (Rec10, Rec25, Rec27, and Mug20 in S. pombe) associated with chromatin. The resulting structure is related to but not equivalent to the synaptonemal complex.


amyloplast inner membrane

The inner, i.e. lumen-facing, lipid bilayer of the amyloplast envelope; also faces the amyloplast stroma.


perisynaptic space

The extracellular region immediately adjacent to to a synapse.


megagametophyte egg cell nucleus

The nucleus of a plant egg cell. This nucleus is found at the micropylar end of the embryo.


lignin network

An extracellular matrix part that consists of lignin in the form of a three-dimensional polymeric network. Lignins are complex racemic aromatic heteropolymers derived from a variety of phenylpropane monomers coupled together by an assortment of carbon-carbon and ether linkages. Lignin is crucial for structural integrity of the cell wall and stiffness and strength of the stem. In addition, lignin waterproofs the cell wall, enabling transport of water and solutes through the vascular system, and plays a role in protecting plants against pathogens.


hyphal septin band

A septin band, i.e. a diffuse ring composed of a series of septin bars running parallel to the long axis of the cell, located at the junction between the mother cell and the germ tube (hypha) of a fungal cell growing filamentously.


pilus shaft

The long, slender, mid section of a pilus.


lower tip-link density

An electron-dense plaque at the lower end of a stereocilia tip link that provides the anchor in the stereocilia membrane at the tip of the stereocilium from which the tip link rises.


sieve area

A pit-like area in the cell wall of a sieve element; contains pores lined with callose and occupied by strands of protoplasmic material that interconnect the protoplasts of contiguous sieve elements.


nucleoplasmic side of nuclear pore

The side of the nuclear pore complex (NPC) that faces the nucleoplasm.


autolysosome

A type of secondary lysosome in which a primary lysosome has fused with the outer membrane of an autophagosome. It is involved in the second step of autophagy in which it degrades contents with acidic lysosomal hydrolases.


secondary lysosome

Vacuole formed by the fusion of a lysosome with an organelle (autosome) or with a primary phagosome.


left lateral basal body pair

Set of two basal bodies found in Giardia species (trophozoite stage). It comprises the anterior and ventral basal bodies located to the right of the left nucleus of the trophozoite when viewed dorsally.


host cell centrosome

A structure in a host cell comprised of a core structure (in most organisms, a pair of centrioles) and peripheral material from which a microtubule-based structure, such as a spindle apparatus, is organized. Centrosomes occur close to the nucleus during interphase in many eukaryotic cells, though in animal cells it changes continually during the cell-division cycle.


stereocilia tip link

A stereocilia link that is formed by a fine filament running more or less vertically upward from the tip of each shorter stereocilium to attach at a higher point on its adjacent taller neighbor. Tilting the bundle puts tension on the filaments, which pull on mechanically gated ion channels in the membrane of the stereocilia.


axonemal outer doublet

Part of an axoneme consisting in a doublet microtubule. Nine of these outer doublets form the 9+0 axoneme, while the 9+2 axoneme also contains a central pair. Dynein arms attached to the doublets provide the mechanism of movement of the cilium.


dendritic spine

A small, membranous protrusion from a dendrite that forms a postsynaptic compartment, typically receiving input from a single presynapse. They function as partially isolated biochemical and an electrical compartments. Spine morphology is variable:they can be thin, stubby, mushroom, or branched, with a continuum of intermediate morphologies. They typically terminate in a bulb shape, linked to the dendritic shaft by a restriction. Spine remodeling is though to be involved in synaptic plasticity.


postsynapse

The part of a synapse that is part of the post-synaptic cell.


thorny excrescence

Large complex spine protruding from a dendrite. Each excrescence is formed by a cluster of spine heads.


postsynapse of neuromuscular junction

The postsynapse of a neuromuscular junction. In vertebrate muscles this includes the motor end-plate, consisting of postjunctional folds of the sarcolemma.


dinoflagellate sulcus

A cell surface furrow that occurs on the ventral side of a dinoflagellate cell. It partially houses the longitudinal flagellum. The sulcus intersects with the cingulum on the ventral side of a dinoflagellate cell.


cell surface furrow

A furrow that may be found on the cell surface. Examples include the cingulum and sulcus found in some dinoflagellates.


dinoflagellate cingulum

A cell surface furrow that wraps around a dinoflagellate cell; the transverse flagellum lies in it.


dinoflagellate sulcal notch

A dinoflagellate sulcus that extends all the way to the posterior end of the cell (also known as antapex). The presence of a sulcal notch makes the dinoflagellate hypocone appear bilobed.


dinoflagellate apical groove

A cell surface furrow (or groove) found on a dinoflagellate apex. It typically loops around the apex.


attachment organelle membrane

The lipid bilayer surrounding an attachment organelle. This is a region of the cell membrane facing the environment - in mycoplasma, part of the mycolate outer membrane.


T=219 icosahedral capsid

The protein coat that surrounds the infective nucleic acid in some virus particles where the subunits (capsomeres) are arranged to form an icosahedron with T=219 symmetry. T=219 icosahedral capsid is composed of 12 pentameric and 2180 hexameric capsomeres for a total of 13140 capsid proteins.


microtubule minus-end

The end of a microtubule that does not preferentially grow (polymerize).


microtubule end

Any end of a microtubule. Microtubule ends differ in that the so-called microtubule plus-end is the one that preferentially grows by polymerization, with respect to the minus-end.


post-anaphase array microtubule end

Any microtubule end that is part of a post-anaphase array microtubule.


microtubule plus-end

The growing (plus) end of a microtubule. In vitro, microtubules polymerize more quickly at the plus end than at the minus end. In vivo, microtubule growth occurs only at the plus end, and the plus end switches between periods of growth and shortening, a behavior known as dynamic instability.


mitotic spindle astral microtubule end

Any microtubule end that is part of a mitotic spindle astral microtubule.


cytoplasmic microtubule minus-end

A microtubule minus end that is part of a cytoplasmic microtubule.


plasmodesmatal endoplasmic reticulum

Endoplasmic reticulum found in plasmodesmata, junctions connecting the cytoplasm of adjacent plant cells.


sarcoplasmic reticulum

A fine reticular network of membrane-limited elements that pervades the sarcoplasm of a muscle cell; continuous over large portions of the cell and with the nuclear envelope; that part of the endoplasmic reticulum specialized for calcium release, uptake and storage.


smooth endoplasmic reticulum

The smooth endoplasmic reticulum (smooth ER or SER) has no ribosomes attached to it. The smooth ER is the recipient of the proteins synthesized in the rough ER. Those proteins to be exported are passed to the Golgi complex, the resident proteins are returned to the rough ER and the lysosomal proteins after phosphorylation of their mannose residues are passed to the lysosomes. Glycosylation of the glycoproteins also continues. The smooth ER is the site of synthesis of lipids, including the phospholipids. The membranes of the smooth ER also contain enzymes that catalyze a series of reactions to detoxify both lipid-soluble drugs and harmful products of metabolism. Large quantities of certain compounds such as phenobarbital cause an increase in the amount of the smooth ER.


membrane stack

A configuration of endoplasmic reticulum (ER) found in Purkinje cells in the cerebellum and in axons in the lateral vestibular nucleus, consisting of parallel and interconnecting tubules whose outer surfaces are covered by particles or ringlike structures.


rough endoplasmic reticulum

The rough (or granular) endoplasmic reticulum (ER) has ribosomes adhering to the outer surface; the ribosomes are the site of translation of the mRNA for those proteins which are either to be retained within the cisternae (ER-resident proteins), the proteins of the lysosomes, or the proteins destined for export from the cell. Glycoproteins undergo their initial glycosylation within the cisternae.


interphase microtubule organizing center

A microtubule organizing center found in interphase cells, which organize a longitudinal array of three to five MT bundles from the nuclear envelope during interphase. Each MT bundle is composed of two to seven MTs arranged in an antiparallel configuration, with the dynamic MT plus ends extending toward the cell tips and stable minus ends near the nucleus.


host intracellular part

Any constituent part of the living contents of a host cell; the matter contained within (but not including) the plasma membrane, usually taken to exclude large vacuoles and masses of secretory or ingested material. In eukaryotes it includes the nucleus and cytoplasm. The host is defined as the larger of the organisms involved in a symbiotic interaction.


host cell synaptic vesicle

A secretory organelle of a host cell, some 50 nm in diameter, of presynaptic nerve terminals; accumulates in high concentrations of neurotransmitters and secretes these into the synaptic cleft by fusion with the 'active zone' of the presynaptic plasma membrane.


Maurer's cleft

A disk-like structure that appears at the periphery of a red blood cell infected by an apicomplexan parasite, characterized by a translucent lumen and an electron-dense coat of variable thickness; often appears to be tethered to the host cell membrane by fibrous connections with the erythrocyte cytoskeleton.


host cell mitochondrial intermembrane space

The region between the inner and outer lipid bilayers of the host cell mitochondrial envelope.


host cell plastid

Any member of a family of organelles as found in the cytoplasm of host cells, which are membrane-bounded and contain DNA. The host is defined as the larger of the organisms involved in a symbiotic interaction.


host symbiosome

A double-enveloped cell compartment, composed of the endosymbiont with its plasmalemma (as inner envelope) and an outer envelope (the perisymbiontic membrane) derived from the host cell.


host cell synaptic vesicle membrane

The lipid bilayer surrounding a host synaptic vesicle.


host cell endosome lumen

The volume enclosed by the membranes of the host cell endosome.


host thylakoid membrane

The pigmented membrane of any host thylakoid.


host cell nuclear part

Any constituent part of a host cell's nucleus, a membrane-bounded organelle of eukaryotic cells in which chromosomes are housed and replicated. The host is the larger of the organisms involved in a symbiotic interaction.


host cell Cajal body

A class of nuclear body in the eukaryotic host cell, first seen after silver staining by Ramon y Cajal in 1903, enriched in small nuclear ribonucleoproteins, and certain general RNA polymerase II transcription factors; ultrastructurally, they appear as a tangle of coiled, electron-dense threads roughly 0.5 micrometers in diameter; involved in aspects of snRNP biogenesis; the protein coilin serves as a marker for Cajal bodies. Some argue that Cajal bodies are the sites for preassembly of transcriptosomes, unitary particles involved in transcription and processing of RNA. The host is the larger of the organisms involved in a symbiotic interaction.


host intracellular organelle

Organized structure of distinctive morphology and function, occurring within the host cell. Includes the nucleus, mitochondria, plastids, vacuoles, vesicles, ribosomes and the cytoskeleton. Excludes the plasma membrane. The host is defined as the larger of the organisms involved in a symbiotic interaction.


host cell smooth endoplasmic reticulum

The irregular network of unit membranes, visible only by electron microscopy, that occurs in the host cell cytoplasm of many eukaryotic cells. The membranes form a complex meshwork of tubular channels, which are often expanded into slitlike cavities called cisternae. The host smooth ER has no ribosomes adhering to the outer surface.


host cell mitochondrial envelope

The double lipid bilayer enclosing the host cell mitochondrion and separating its contents from the host cell cytoplasm; includes the intermembrane space.


symbiont-containing vacuole

Membrane-bounded vacuole within a host cell in which a symbiont organism resides. The vacuole membrane is derived from both the host and symbiont.


double membrane vesicle viral factory lumen

The volume surrounded by the inner membrane of a double membrane vesicle viral factory.


host cell cytoplasm part

Any constituent part of the host cell cytoplasm, all of the contents of a cell excluding the plasma membrane and nucleus, but including other subcellular structures. The host is defined as the larger of the organisms involved in a symbiotic interaction.


host cell viral nucleoid

The region of a host cell that contains the viral genome.


host thylakoid

A membranous cellular structure within the host cell that bears the photosynthetic pigments in plants, algae, and cyanobacteria. In cyanobacteria thylakoids are of various shapes and are attached to, or continuous with, the host plasma membrane. In eukaryotic host cells they are flattened, membrane-bounded disk-like structures located in the chloroplasts; in the chloroplasts of higher plants the thylakoids form dense stacks called grana. Isolated thylakoid preparations can carry out photosynthetic electron transport and the associated phosphorylation.


T=147 icosahedral capsid

The protein coat that surrounds the infective nucleic acid in some virus particles where the subunits (capsomeres) are arranged to form an icosahedron with T=147 symmetry. T=147 icosahedral capsid is composed of 12 pentameric and 1460 hexameric capsomeres for a total of 8820 capsid proteins.


T=169 icosahedral viral capsid

The protein coat that surrounds the infective nucleic acid in some virus particles where the subunits (capsomeres) are arranged to form an icosahedron with T=169 symmetry. T=169 icosahedral capsid is composed of 12 pentameric and 1680 hexameric capsomeres for a total of 10140 capsid proteins.


postsynaptic specialization membrane

The membrane component of the postsynaptic specialization. This is the region of the postsynaptic membrane in which the population of neurotransmitter receptors involved in synaptic transmission are concentrated.


postsynaptic specialization membrane of symmetric synapse

The membrane component of the postsynaptic specialization of a symmetic synapse. This is the region of the postsynaptic membrane in which the population of neurotransmitter receptors involved in synaptic transmission are concentrated.


postsynaptic density membrane

The membrane component of the postsynaptic density. This is the region of the postsynaptic membrane in which the population of neurotransmitter receptors involved in synaptic transmission are concentrated.


nucleoid

The region of a virus, bacterial cell, mitochondrion or chloroplast to which the nucleic acid is confined.


type Ib terminal bouton

Terminal inflated portion of the axon of a glutamatergic neuron, containing the specialized apparatus necessary for the tonic release neurotransmitters that will induce the contraction of muscle. Type Ib terminal boutons are larger than type Is terminal boutons.


basal distal dendrite

Any dendrite in a dendritic tree that emerges near the basal pole of a neuron (e.g. in bipolar neurons, basal dendrites are either on the same side of the soma as the axon, or project toward the axon), and which is farthest away from the neuronal cell body (the soma).


cell wall-bounded periplasmic space

The region between the plasma membrane and the cell wall in organisms lacking an outer cell membrane such as yeast and Gram positive bacteria. The region is thinner than the equivalent in Gram negative bacteria.


monolayer-surrounded lipid storage body outer lipid monolayer

The single layer of phopholipids surrounding a lipid storage body.


left posteriolateral flagellum

A cilium (also called flagellum) found in Giardia species (trophozoite stage). It is nucleated by the left posteriolateral basal body and extends cytoplasmically toward the cell posterior, marking the left anterior boundary of the lateral shield and the left lateral region of the funis before exiting at the left lateral region of the cell body.


dendritic branch

A dendrite arising from another dendrite.


Golgi apparatus

A membrane-bound cytoplasmic organelle of the endomembrane system that further processes the core oligosaccharides (e.g. N-glycans) added to proteins in the endoplasmic reticulum and packages them into membrane-bound vesicles. The Golgi apparatus operates at the intersection of the secretory, lysosomal, and endocytic pathways.


postsynaptic Golgi apparatus

The network of the Golgi apparatus structures located within the postsynapse.


hyphal tip

The end, or tip, of a fungal hypha, where polarized growth occurs during hyphal elongation.


nucleolar chromatin

The portion of nuclear chromatin associated with the nucleolus; includes the DNA encoding the ribosomal RNA.


nucleolus-associated heterochromatin

Dense particles of heterochromatin, consisting of a loosely twisted strand about 600 Angstrom thick, found associated with the nucleolus.


nucleolus organizer region

A region of a chromosome where nucleoli form during interphase, and where genes encoding the largest rRNA precursor transcript are tandemly arrayed.


dendritic spine neck

Part of the dendritic spine that connects the dendritic shaft to the head of the dendritic spine.


S bouton

Synaptic bouton found in the ventral horn of the spinal cord. S boutons range in diameter from 0.5 to 8 um and contain spherical synaptic vesicles.


outer mucus layer

The outer of two mucus layers secreted by epithelial cells in the colon; the outer mucus layer is loosely packed and can be colonized by bacteria.


omegasome membrane

Any membrane that is part of an omegasome.


smooth endoplasmic reticulum cisterna

A subcompartment of the smooth endoplasmic reticulum consisting of lumenal expansion into a flattened, disc-shaped cavity.


subrhabdomeral cisterna

A membrane-bounded compartment that is found at the base of the rhabdomere and contains stored calcium, InsP3 receptors and smooth endoplasmic reticulum Ca2+-ATPase.


sub-surface cisterna

Specialization of the hypolemmal cisterna consisting of either single profiles or closely apposed stacks of endoplasmic reticulum in which the lumen is obliterated, lying 10-20 nm beneath the plasma membrane.


hypolemmal cisterna

Specialized part of the smooth endoplasmic reticulum that closely underlies the plasma membrane, usually within 60 nm or closer.


pseudopodium membrane

The portion of the plasma membrane surrounding a pseudopodium.


ciliary pocket

Invagination of the plasma membrane from which a cilium (also called flagellum) protrudes.


membrane microdomain

A membrane region with a lipid composition that is distinct from that of the membrane regions that surround it.


caveola neck

A membrane microdomain that forms a necklace around the bulb (crater) of a caveola. Intramembrane particles are concentrated in this region and cytoskeletal components, including actin, are highly enriched in the area underlying it.


eisosome membrane domain/MCC

A plasma membrane part that is composed of a furrow-like plasma membrane domain and associated integral transmembrane proteins.


dendritic spine membrane

The portion of the plasma membrane surrounding a dendritic spine.


host peribacteroid membrane

A host-derived membrane that surrounds one or more bacteroids (such as nitrogen-fixing bacteroids within legume root nodule cells).


transverse flagellum

A motile cilium found in dinoflagellates. It coils around the cell and provides the forward thrust for motility. It is often contained in a furrow called the cingulum, and emerges from a flagellar pore located in the cingulum.


sculpture element

The third layer of the sexine.


platelet glycocalyx

The carbohydrate rich layer at the outermost periphery of a platelet.


right tetrad

Set of four basal bodies found in Giardia species (trophozoite stage). It comprises the right lateral basal body pair and the right middle basal body pair (i.e. the anterior, ventral, caudal and posteriolateral basal bodies located to the left of the right nucleus of the trophozoite when viewed dorsally).


ventral disc supernumerary microtubule array

A partial left-handed spiral array of microtubules that lies generally dorsal to the main ventral disc microtubule array in Giardia species (trophozoite stage).


axonemal central pair

Part of the axoneme consisting of the inner two microtubule doublets of the 9+2 axoneme occurring in most motile cilia.


endocytic vesicle lumen

The volume enclosed by the membrane of an endocytic vesicle.


phagocytic vesicle lumen

The volume enclosed by the membrane of a phagocytic vesicle.


clathrin-coated endocytic vesicle lumen

The volume enclosed by the membrane of a clathrin-coated endocytic vesicle.


early phagosome lumen

The volume enclosed by the membrane of an eary phagosome.


host apoplast

The apoplast region surrounding a host plant cell. Plants may be described as having two major compartments: the living symplast and the non-living apoplast. The apoplast is external to the plasma membrane and includes cell walls, intercellular spaces and the lumen of dead structures such as xylem vessels. Water and solutes pass freely through it. The host is defined as the larger of the organisms involved in a symbiotic interaction.


left ventral basal body

Any ciliary basal body that is part of a left ventral flagellum found in Giardia species (trophozoite stage).


organic molecular entity

Any molecular entity that contains carbon.


heteroorganic entity

A heteroorganic entity is an organic molecular entity in which carbon atoms or organic groups are bonded directly to one or more heteroatoms.


organochalcogen compound

An organochalcogen compound is a compound containing at least one carbon-chalcogen bond.


organooxygen compound

An organochalcogen compound containing at least one carbon-oxygen bond.


endospore-forming forespore

Portion of the cell formed during the process of bacterial sporulation that will ultimately become the core of the endospore. An endospore is a type of dormant cell that is resistant to adverse conditions.


inner layer of spore wall

Either of the two innermost layers of the spore wall, as described in Saccharomyces.


9+2 non-motile cilium

A non-motile cilium where the axoneme has a ring of nine outer microtubule doublets plus two central microtubules (and is therefore called a 9+2 axoneme).


kinocilium

A nonmotile primary cilium that is found at the apical surface of auditory receptor cells. The kinocilium is surrounded by actin-based stereocilia.


granum

Distinct stack of lamellae seen within chloroplasts. Grana contain the pigments, electron transfer compounds, and enzymes essential to the light-dependent reactions of photosynthesis.


internode region of axon

An axon part that is located between the nodes of Ranvier and surrounded by compact myelin sheath.


cleavage body

A nuclear body that contains proteins involved in pre-mRNA 3'-end cleavage and polyadenylation, such as DDX1, CSTF2 and CPSFs, as well as the transcription factors TFIIE and TFIIF. Cleavage bodies are localized adjacent to Cajal bodies and are involved in mRNA3'-end processing.


F bouton

Synaptic bouton found in the ventral horn of the spinal cord. F boutons range in diameter from 0.5 to 7 um and contain flattened or pleomorphic synaptic vesicles.


eisosome

A cell part that is composed of the eisosome membrane or MCC domain, a furrow-like plasma membrane sub-domain and associated integral transmembrane proteins, and the proteins (eisosome filaments) that form a scaffolding lattice on the cytoplasmic face. Eisosomes broadly affect overall plasma membrane organization.


Organized structure of distinctive morphology and function, not bounded by a lipid bilayer membrane and occurring outside the cell.


cellulosome

An extracellular multi-enzyme complex containing up to 11 different enzymes aligned on a non-catalytic scaffolding glycoprotein. Functions to hydrolyze cellulose.


mating projection base

The region where the mating projection meets the bulk of the cell, in unicellular fungi exposed to mating pheromone.


synaptic cleft

The narrow gap that separates the presynaptic and postsynaptic membranes, into which neurotransmitter is released.


apoplast

The cell membranes and intracellular regions in a plant are connected through plasmodesmata, and plants may be described as having two major compartments: the living symplast and the non-living apoplast. The apoplast is external to the plasma membrane and includes cell walls, intercellular spaces and the lumen of dead structures such as xylem vessels. Water and solutes pass freely through it.


perivitelline space

The space between the membrane of an oocyte and a surrounding membranous structure (zona pellucida or perivitelline membrane).


lysosomal lumen

The volume enclosed within the lysosomal membrane.


endolysosome lumen

The volume enclosed by the membrane of an endolysosome. An endolysosome is a transient hybrid organelle formed by fusion of a late endosome with a lysosome.


cytolytic granule

A specialized secretory lysosome that is present in cells with cytolytic capability such as cytotoxic T lymphocytes and natural killer cells. Cytolytic granules mediate the storage and regulated excretion of lytic molecules for killing of target cells.


porous cell septum

A septum or cross wall which does not entirely span the space between two portions of cell wall and may contain a specialized central pore structure. A porous septum allows the movement of organelles and/or cytoplasm between compartments.


dolipore septum

A septum, or cross-wall, between two portions of a cell or hypha; contains a central pore around which the septum is swollen to form a barrel-shaped structure; pore is covered on each side of the septum by a septal pore cap (parenthosome).


host cell synapse

The junction between a nerve fiber of one host neuron and another host neuron or muscle fiber or glial cell; the site of interneuronal communication.


cellular bud neck septin structure

Any of a series of septin structures that are localized in the bud neck of a budding fungal cell during the cell cycle.


annular furrow extracellular matrix

The extracellular matrix part that is a regularly spaced indentation in the outer cortical layer of the cuticle. The pattern of annular furrows corresponds to sites of invaginations in hypodermal cell membranes that, in turn, correspond to submembranous regions where actin microfilament bundles assemble early in lethargus, the first phase of the molting cycle in which activity and feeding decline.


yolk granule

Discrete structures that partition the water-insoluble portion of the yolk of oocytes and ova, which may or may not be membrane enclosed.


symbiont-containing vacuolar membrane network

Tubular network of extensions from the symbiont-containing vacuole membrane that protrude into the host cytoplasm.


cis-Golgi network membrane

The lipid bilayer surrounding any of the compartments that make up the cis-Golgi network.


pellicle

The structure enclosing certain parasite cells such as certain apicomplexa and Euglenozoa; consists of the cell membrane with its associated infrastructure of microtubules, microfilaments and other organelles.


spine apparatus

A specialization of the endomembrane system found in some classes of dendritic spines consisting of two or more closely apposed lamellae with interspersed electron dense material. The endomembrane component is continuous with the smooth endoplasmic reticulum.


dendritic tuft

The terminal specialization found in some types of dendrites which consists of numerous small terminal branches, giving the dendrite a tufted appearance.


peribacteroid fluid

The soluble material inside the peribacteroid membrane, but outside of the bacteroid, within a bacteroid-containing symbiosome.


spindle matrix

A proteinaceous, nuclear-derived structure that embeds the microtubule spindle apparatus from pole to pole in a microtubule-independent manner during mitosis.


climbing fiber

The axon of inferior olive neuron that projects to the cerebellar cortex, largely via the inferior cerebellar peduncle. They range in diameter from 1-3 um and are myelinated until they enter the granule cell layer. They give off collaterals to the deep cerebellar nuclei. They synapse extensively with the dendrites of Purkinje cells in the molecular layer, where each fiber branches repeatedly to climb along the Purkinje cell dendritic tree. Each Purkinje cell is innervated by only a single climbing fiber.


spine synapse

A type of synapse occurring between an axon and a dendritic spine.


brush border

The dense covering of microvilli on the apical surface of an epithelial cell in tissues such as the intestine, kidney, and choroid plexus; the microvilli aid absorption by increasing the surface area of the cell.


cellular bud scar

Crater-like ring of chitinous scar tissue located on the surface of the mother cell. It is formed after the newly emerged daughter cell separates thereby marking the site of cytokinesis and septation. The number of bud scars that accumulate on the surface of a cell is a useful determinant of replicative age.


exopher

An extracellular vesicle that is approximately four microns in diameter, released by budding out of cells into the extracellular space, and hypothesized to be a mechanism for disposal of unwanted cellular material including protein aggregates and damaged organelles.


female germline ring canal outer rim

An electron opaque backbone of the insect ovarian ring canal that is a part of or adjacent to the plasma membrane. The outer rim is established as the cleavage furrow is arrested, and contains F-actin, anillin, glycoproteins and at least one a protein with a high content of phosphorylated tyrosine residues.


free sarcoplasmic reticulum membrane

The part of the sarcoplasmic reticulum membrane that contains calcium pumps and is devoted to calcium uptake. The free sarcoplasmic reticulum membrane consists of the longitudinal sarcoplasmic reticulum membrane and the non-junctional region of the terminal cisterna membrane.


filiform apparatus

A complex of cell wall invaginations in a synergid cell, similar to those in transfer cells.


endospore core

An intracellular part that represents the innermost portion of an endospore; the endospore core is dehydrated, enriched in dipicolinic acid and divalent cations, and metabolically inactive.


phagocytic cup lip

The tip or margin of the progressing circular lamella that engulfs a particle during phagocytosis. When the two lips of the cup fuse it is converted into a phagosome.


chlorosome envelope

The structure, composed of a monolayer of glycolipids with embedded proteins, that encloses the pigments and other contents of the chlorosome.


organelle-enclosing lipid monolayer

A lipid monolayer that surrounds and encloses an organelle.


microneme

A small, elongated secretory organelle that forms part of the apical complex, located along the main axis of an apicomplexan parasite cell within the extreme apical region and at the periphery under the inner membrane complex. Of the specialized secretory compartments identified in apicomplexans, micronemes discharge their contents first, during initial contact of the parasite's apical pole with the host cell surface. Micronemal proteins function during parasite attachment and penetration into the target cell.


mitochondrial crista

Any of the inward folds of the mitochondrial inner membrane. Their number, extent, and shape differ in mitochondria from different tissues and organisms. They appear to be devices for increasing the surface area of the mitochondrial inner membrane, where the enzymes of electron transport and oxidative phosphorylation are found. Their shape can vary with the respiratory state of the mitochondria.


magnetosome

A membrane-bound organelle that envelops particles of magnetic iron minerals in magnetotactic bacteria. Magnetosomes form linear chains that align along the cellular motility axis at midcell and function in bacterial navigation along the Earth's magnetic field. They are formed by invagination of the cell inner membrane; in some species they remain connected to the inner membrane, in others they pinch off to form independent intracellular vesicles.


p-block molecular entity

A main group molecular entity that contains one or more atoms of a p-block element.


chalcogen molecular entity

Any p-block molecular entity containing a chalcogen.


dinoflagellate epicone

The part of a dinoflagellate cell above the cingulum; also referred to as the anterior portion of a dinoflagellate cell. It is separated from the hypocone by the cingulum.


etioplast stroma

The space enclosed by the double membrane of an etioplast but excluding the prothylakoid space. It contains the etioplast DNA.


mating projection

The projection formed by unicellular fungi in response to mating pheromone.


central element

A structural unit of the synaptonemal complex found between the lateral elements.


ascus epiplasm

Ascus cytoplasm that is not packaged into ascospores.


phragmosome

A flattened membranous vesicle containing cell wall components.


eyespot apparatus

A small pigmented organelle used in single-celled organisms to detect light.


C zone

A region of the A band in which myosin-binding protein C is located and that can be seen by electron microscopy. This is a functional zone that also includes myosin.


Gemini of coiled bodies

Nuclear bodies frequently found near or associated with Cajal bodies (also called coiled bodies or CBs). Gemini of coiled bodies, or 'gems', are similar in size and shape to CBs, and often indistinguishable under the microscope. Unlike CBs, gems do not contain small nuclear ribonucleoproteins (snRNPs); they contain a protein called survivor of motor neurons (SMN) whose function relates to snRNP biogenesis. Gems are believed to assist CBs in snRNP biogenesis, and to play a role in the etiology of spinal muscular atrophy (SMA).


nuclear body

Extra-nucleolar nuclear domains usually visualized by confocal microscopy and fluorescent antibodies to specific proteins.


LYSP100-associated nuclear domain

A nuclear body that is enriched in the lymphoid cell-specific protein LYSp100B; LANDs are globular, electron-dense structures and are morphologically distinct from the annular structures characteristic of PML bodies.


omega speckle

A nucleoplasmic speckle distributed in the interchromatin space of cells in close proximity to chromatin. Omega speckles are distinct from interchromatin granules and contain heterogeneous nuclear RNA-binding proteins (hnRNPs).


paraspeckles

Discrete subnuclear bodies in the interchromatin nucleoplasmic space, often located adjacent to nuclear specks. 10-20 paraspeckles are typically found in human cell nuclei.


nuclear speck

A discrete extra-nucleolar subnuclear domain, 20-50 in number, in which splicing factors are seen to be localized by immunofluorescence microscopy.


nuclear dicing body

A small round nuclear body, measuring 0.2-0.8 microns in diameter that is diffusely distributed throughout the nucleoplasm. Several proteins known to be involved in miRNA processing have been localized to these structures. D-bodies are thought to be involved in primary-miRNA processing and/or storage/assembly of miRNA processing complexes.


interchromatin granule

A class of nuclear body measuring 20-25 nm in diameter and distributed throughout the interchromatin space, linked together by thin fibrils. They are believed to be storage centers for various snRNAs, snRNPs, serine/arginine-rich proteins and RNA polymerase II. A typical mammalian cell contains 25-50 clusters of interchromatin granules. Interchromatin granule clusters do not contain the heterogeneous nuclear RNA-binding proteins (hnRNPs).


sphere organelle

A nuclear body that is found in the germinal vesicles of amphibian oocytes, and consist of three major parts: a remarkably spherical body about 5-10 pm in diameter, smaller spherical or nearly spherical granules on the surface, and inclusions of various sizes that strongly resemble the surface granules. The parts of the sphere organelle have distinct compositions, including splicing snRNAs and proteins.


Cajal body

A class of nuclear body, first seen after silver staining by Ramon y Cajal in 1903, enriched in small nuclear ribonucleoproteins, and certain general RNA polymerase II transcription factors; ultrastructurally, they appear as a tangle of coiled, electron-dense threads roughly 0.5 micrometers in diameter; involved in aspects of snRNP biogenesis; the protein coilin serves as a marker for Cajal bodies. Some argue that Cajal bodies are the sites for preassembly of transcriptosomes, unitary particles involved in transcription and processing of RNA.


nuclear exosome focus

An nuclear body involved in nuclear mRNA surveilllance. Contains at least Mmi1, or an ortholog of it, and the nuclear exosome.


pseudopodium

A temporary protrusion or retractile process of a cell, associated with flowing movements of the protoplasm, and serving for locomotion and feeding.


dense fibrillar component

A structure found in the nucleolus, which contains newly synthesized preribosomal RNA (pre-rRNA) and a collection of proteins.


cell body fiber

A neuron projection that is found in unipolar neurons and corresponds to the region between the cell body and the point at which the single projection branches.


chromoplast stroma

The space enclosed by the double membrane of a chromoplast but excluding the photosynthetic material.


apicolateral plasma membrane

The apical end of the lateral plasma membrane of epithelial cells.


Golgi apparatus subcompartment

A compartment that consists of a lumen and an enclosing membrane, and is part of the Golgi apparatus.


Golgi trans cisterna

The Golgi cisterna farthest from the endoplasmic reticulum; the final processing compartment through which proteins pass before exiting the Golgi apparatus; the compartment in which N-linked protein glycosylation is completed.


Golgi cisterna

Any of the thin, flattened membrane-bounded compartments that form the central portion of the Golgi complex.


Golgi stack

The set of thin, flattened membrane-bounded compartments, called cisternae, that form the central portion of the Golgi complex. The stack usually comprises cis, medial, and trans cisternae; the cis- and trans-Golgi networks are not considered part of the stack.


apical proximal dendrite

The dendrite of the dendritic tree, which emerges near the apical pole of a neuron, and which is the closest to the cell body of the neuron (the soma).


right anterior flagellum

A cilium (also called flagellum) found in Giardia species (trophozoite stage). It originates at the right anterior basal body, extends laterally through the cytoplasm, crosses the left anterior axoneme, and exits as a membrane-bound flagellum on the anterior right side of the cell.


germline ring canal

Germline specific intercellular bridge. During cyst formation in insects, ring canals interconnect the cells of the cyst, facilitating the passage of cytoplasmic components between cells.


female germline ring canal

An intercellular bridge that connects the germline cells of a female cyst.


male germline ring canal

An intercellular bridge that connects the germline cells of a male cyst.


mitochondrial envelope

The double lipid bilayer enclosing the mitochondrion and separating its contents from the cell cytoplasm; includes the intermembrane space.


vestibular calyx terminal

The giant, cup-shaped axon terminal of a vestibular afferent neuron, serving as a post-synaptic contact to a type I hair cell.


neuron projection terminus

The specialized, terminal region of a neuron projection such as an axon or a dendrite.


calyx of Held

The terminal specialization of a calyciferous axon which forms large synapses in the mammalian auditory central nervous system.


axon terminus

Terminal inflated portion of the axon, containing the specialized apparatus necessary to release neurotransmitters. The axon terminus is considered to be the whole region of thickening and the terminal button is a specialized region of it.


cone cell pedicle

A specialized axon terminus which is produced by retinal cone cells. Pedicles are large, conical, flat end-feet (8-10 micrometers diameter) of the retinal cone axon that lie more or less side by side on the same plane at the outer edge of the outer plexiform layer (OPL).


Herring body

The dilated terminal portions of neurosecretory axons constituting the hypothalamohypophyseal tract, found in close proximity to sinusoidal capillaries in the posterior pituitary. Herring bodies consist of aggregates of membrane-bound neurosecretory vesicles where oxytocin or antidiuretic hormone (ADH) are stored prior to release. Each Herring body also contains ATP and either neurophysin I or neurophysin II which bind to oxytocin and ADH, respectively.


nuclear envelope lumen

The region between the two lipid bilayers of the nuclear envelope; 20-40 nm wide.


P2 peroxisome

A subform of peroxisome that corresponds to an intermediate in a peroxisome assembly pathway, which operates by conversion of peroxisomal subforms in the direction P1, P2 -> P3 -> P4 -> P5 -> P6. P2 peroxisomes are distinguished from the other subforms on the bases of buoyant density and protein content; they are the least dense of the subforms observed.


oral apparatus

Complex basket- or funnel-like structure used by the cell to collect food and channel it to the cytostome; includes specialized sub-structures made up of closely-spaced cilia and underlying basal bodies and fibrillar systems.


uropod membrane

The portion of the plasma membrane surrounding a uropod.


cell trailing edge membrane

The portion of the plasma membrane surrounding the trailing edge of a motile cell.


procentriole

A cellular structure that is the site of a developing centriole, which will become a microtubule organizing center. During the canonical pathway of centriole duplication that occurs during the cell division cycle, procentrioles grow at the proximal ends of both mother and daughter centrioles. In the newly divided cells, the original mother and daughter centrioles become mother centrioles while the procentrioles become the new daughter centrioles. Procentrioles can also arise from de novo pathways that occur in multiciliated cells. In ciliated epithelial cells, numerous procentrioles arise form electron dense material referred to as fibrous granules and deuterosomes. The pathway of procentriole formation in multiciliated protists appears to be similar to that in mammalian multiciliated epithelium. In sperm of primative land plants, multiple procentrioles are formed from a blepharoplast giving rise to multicilated sperm cells.


storage vacuole

A vacuole that functions primarily in the storage of materials, including nutrients, pigments, waste products, and small molecules.


fungal-type vacuole

A vacuole that has both lytic and storage functions. The fungal vacuole is a large, membrane-bounded organelle that functions as a reservoir for the storage of small molecules (including polyphosphate, amino acids, several divalent cations (e.g. calcium), other ions, and other small molecules) as well as being the primary compartment for degradation. It is an acidic compartment, containing an ensemble of acid hydrolases. At least in S. cerevisiae, there are indications that the morphology of the vacuole is variable and correlated with the cell cycle, with logarithmically growing cells having a multilobed, reticulated vacuole, while stationary phase cells contain a single large structure.


reservosome

A large membrane-bound endocytic organelle present only in members of the Schizotrypanum subgenus of the Trypanosoma genus and is defined as the site of storage of endocytosed macromolecules and lysosomal enzymes. It is found at the posterior end of epimastigote forms of Trypanosoma cruzi, but absent in amastigotes and trypomastigotes.


terminal cisterna

The portion of sarcoplasmic reticulum devoted to calcium ion storage and calcium ion release.


stigma papilla

A plant cell papilla that is part of a stigma papilla cell.


apical lamina of hyaline layer

A fibrous network that is part of the hyalin layer extracellular matrix. The apical lamina is thought to be principally composed of the glycoproteins fibropellins. This matrix has been found in echinoderms.


reservosome membrane

The lipid bilayer surrounding a reservosome.


left ventral flagellum

A cilium (also called flagellum) found in Giardia species (trophozoite stage). It is nucleated by the left ventral basal body and exits the cell body proximally and dorsal to the ventral disc.


plasma membrane bounded cell projection

A prolongation or process extending from a cell and that is bounded by plasma membrane, e.g. a cilium, lamellipodium, or axon.


9+0 non-motile cilium

A non-motile cilium where the axoneme has a ring of nine outer microtubule doublets but no central microtubules (and is therefore called a 9+0 axoneme).


microspike

A dynamic, actin-rich projection extending from the surface of a migrating animal cell.


growth cone lamellipodium

A thin sheetlike process extended by the leading edge of an axonal or dendritic growth cone; contains a dense meshwork of actin filaments.


basal dendrite

A dendrite that emerges near the basal pole of a neuron. In bipolar neurons, basal dendrites are either on the same side of the soma as the axon, or project toward the axon.


C-fiber

The axon of a dorsal root ganglion cell that are responsive to pain and temperature. C-fibers are small in diameter (0.2-1.5 um) and unmyelinated.


distal dendrite

The dendrite of the dendritic tree that is farthest away from the neuronal cell body (the soma).


proximal dendrite

The dendrite of the dendritic tree that is closest to the neuronal cell body (the soma).


dendritic tree

The entire complement of dendrites for a neuron, consisting of each primary dendrite and all its branches.


rod spherule

A specialized neuron projection which is the site of synaptic transmission produced by retinal rod cells. Rod spherules are small round enlargements of the axon (3-5 micrometers diameter) or even extensions of the cell body.


right posteriolateral flagellum

A cilium (also called flagellum) found in Giardia species (trophozoite stage). It is nucleated by the right posteriolateral basal body and extends cytoplasmically toward the cell posterior, marking the right anterior boundary of the lateral shield and the right lateral region of the funis before exiting at the right lateral region of the cell body.


hippocampal mossy fiber

Axon of dentate gyrus granule cell projecting to hippocampal area CA3, characterized by expansions (mossy fiber expansions) giving the fibers a mossy appearance. These unmyelinated axons were first described by Ramon y Cajal.


CA3 pyramidal cell dendrite

A dendrite of a hippocampal CA3 pyramidal cell.


axonal spine

A spine that originates from the axon, usually from the initial segment.


giant axon

Extremely large, unmyelinated axon found in invertebrates. Has high conduction speeds and is usually involved in panic or escape responses.


cilium

A specialized eukaryotic organelle that consists of a filiform extrusion of the cell surface and of some cytoplasmic parts. Each cilium is largely bounded by an extrusion of the cytoplasmic (plasma) membrane, and contains a regular longitudinal array of microtubules, anchored to a basal body.


filopodium

Thin, stiff, actin-based protrusion extended by the leading edge of a motile cell such as a crawling fibroblast or amoeba, or an axonal or dendritic growth cone, or a dendritic shaft.


dendritic cell dendrite

A branched cellular projection (or cytoplasmic extension) that is extended from the surface of a dendritic immune cell, and which enables the cell to sample luminal pathogens and increase the surface area for antigen presentation to T cells.


rod telodendria

Rod telodendria are projections that originate from the rod pedicle and form gap junctions with other photoreceptors within the outer plexiform layer of the retina.


growth cone filopodium

A thin, stiff protrusion extended by the leading edge of an axonal or dendritic growth cone.


accessory outer segment

A cilium-like cell projection emanating from the inner segment and running alongside the outer segment of photoreceptors.


9+0 motile cilium

A motile cilium where the axoneme has a ring of nine outer microtubule doublets but no central microtubules (and is therefore called a 9+0 axoneme).


9+2 motile cilium

A motile cilium where the axoneme has a ring of nine outer microtubule doublets plus two central microtubules (and is therefore called a 9+2 axoneme).


non-motile cilium

A cilium which may have a variable array of axonemal microtubules but does not contain molecular motors.


cone telodendria

Cone telodendria are projections that originate from the cone pedicle and form gap junctions with other photoreceptors within the outer plexiform layer of the retina.


muscle cell projection

A prolongation or process extending from a muscle cell. A muscle cell is a mature contractile cell, commonly known as a myocyte. This cell has as part of its cytoplasm myofibrils organized in various patterns.


cytoneme

A long, thin, polarized cell projection that contains actin and can extend for distances many times the diameter of the cell. Cytonemes represent extensions of cell cytoplasm and typically have a diameter of approximately 0.2um.


right ventral flagellum

A cilium (also called flagellum) found in Giardia species (trophozoite stage). It is nucleated by the right ventral basal body and exits the cell body proximally and dorsal to the ventral disc.


pollen tube

A tubular cell projection that is part of a pollen tube cell and extends from a pollen grain.


macropinocytic cup

A cell projection that forms at the site of macropinocytosis, a form of endocytosis that results in the uptake of relatively large amounts of extracellular fluid. The macropinocytic cup membrane selectively excludes certain proteins, such as H36 or PM4C4 in Dictyostelium, and the underlying cytoskeleton is enriched in F-actin and coronin.


right caudal flagellum

A cilium (also called flagellum) found in Giardia species (trophozoite stage). It is nucleated by the right caudal basal body, extending cytoplasmically and exiting at the posterior end of the cell body.


primary dendrite

A dendrite emerging from the cell body (the soma) of a neuron.


parallel fiber

A parallel fiber results from the bifurcation of a cerebellar granule cell axon in the molecular layer into two diametrically opposed branches, that are oriented parallel to the long axis of the folium.


neuron spine

A small membranous protrusion, often ending in a bulbous head and attached to the neuron by a narrow stalk or neck.


left anterior flagellum

A cilium (also called flagellum) found in Giardia species (trophozoite stage). It originates at the left anterior basal body, extends laterally through the cytoplasm, crosses the right anterior axoneme, and exits as a membrane-bound flagellum on the anterior left side of the cell.


cerebellar mossy fiber

An axon arising from cerebellar projecting cells in the cochlea, vestibular nuclei, spinal cord, reticular formation, cerebellar nuclei and basilar pontine nuclei. Mossy fibers enter through all three cerebellar peduncles and send collaterals to the deep cerebellar nuclei, then branch in the white matter and terminate in the granule cell layer. Through this branching, a given mossy fiber can innervate several folia. Mossy fibers synapse on granule cells. The synaptic contacts are made at enlargements along the length of the mossy fiber called mossy fiber rosettes. The enlargements of the rosettes give the axons a mossy-looking appearance in Golgi stained preparations.


gemmule

Spine-like process found on some neurons, e.g., periglomerular cells of olfactory cortex.


photoreceptor cell cilium

A specialised 9+0 non-motile cilium found in photoreceptor cells. A ciliary transition zone called 'photoreceptor connecting cilium' links the photoreceptor outer segment to the inner segment.


motile cilium

A cilium which may have a variable arrangement of axonemal microtubules and also contains molecular motors. It may beat with a whip-like pattern that promotes cell motility or transport of fluids and other cells across a cell surface, such as on epithelial cells that line the lumenal ducts of various tissues; or they may display a distinct twirling motion that directs fluid flow asymmetrically across the cellular surface to affect asymmetric body plan organization. Motile cilia can be found in single as well as multiple copies per cell.


proximal neuron projection

The portion of an axon or dendrite that is close to the neuronal cell body.


actin-based cell projection

A cell projection supported by an assembly of actin filaments, and which lacks microtubules.


podocyte primary projection

A cell projection originating from a renal glomerular podocyte and extending to the renal glomerular podocyte foot.


rhabdomere microvillus

Thin cylindrical membrane-covered projection on the surface of a rhabdomere.


left caudal flagellum

A cilium (also called flagellum) found in Giardia species (trophozoite stage). It is nucleated by the left caudal basal body, extending cytoplasmically and exiting at the posterior end of the cell body.


podocyte foot

A cell projection of a podocyte (glomerular visceral epithelial cell) forming a foot-like structure projecting from a podocyte primary projection, that wraps around capillaries of a renal glomerulus. Adjacent feet (pedicels) interdigitate, leaving thin filtration slits between them, which are covered by slit diaphragms.


uropod

A membrane projection with related cytoskeletal components at the trailing edge of a cell in the process of migrating or being activated, found on the opposite side of the cell from the leading edge or immunological synapse, respectively.


cell hair

A long, thin cell projection that contains F-actin and tubulin, with microtubules centrally located and F-actin peripherally located.


longitudinal flagellum

A motile cilium found in dinoflagellates. It trails the cell and acts as a steering rudder. It is often partially contained in a furrow called the sulcus, and emerges from a flagellar pore located in the sulcus.


telodendria

Telodendria are projections that originate from the axon pedicle and form gap junctions with other neurons.


apical distal dendrite

Any dendrite in a dendritic tree that emerges near the apical pole of a neuron, and which is farthest away from the neuronal cell body (the soma).


dentate gyrus mossy fiber

Distinctive, unmyelinated axons produced by dentate gyrus granule cells.


sperm flagellum

A microtubule-based flagellum (or cilium) that is part of a sperm, a mature male germ cell that develops from a spermatid.


dendritic filopodium

A small, membranous protrusion found primarily on dendritic stretches of developing neurons. May receive synaptic input, and can develop into dendritic spines.


basal proximal dendrite

Any dendrite in a dendritic tree that emerges near the basal pole of a neuron (e.g. in bipolar neurons, basal dendrites are either on the same side of the soma as the axon, or project toward the axon), and which is the closest to the cell body of the neuron (the soma).


rhabdomere

The specialized microvilli-containing organelle on the apical surfaces of a photoreceptor cell containing the visual pigment rhodopsin and most of the proteins involved in phototransduction.


dinoflagellate peduncle

A small, flexible, finger-like projection of cytoplasm containing an array of microtubles and located near the flagellar pores in some photosynthetic as well as nonphotosynthetic dinoflagellate species. Its functions are not fully understood, but it has been associated with feeding behavior (phagotrophy).


apical dendrite

A dendrite that emerges near the apical pole of a neuron. In bipolar neurons, apical dendrites are located on the opposite side of the soma from the axon.


phenyloplast

A chloroplast-derived plastid in which the solid form of phenol is stored.


apicoplast

The plastid organelle found in apicomplexans.


etioplast

A plastid arrested in the development of chloroplasts from proplastids due to absence of light or low light conditions.


leucoplast

A colorless plastid involved in the synthesis of monoterpenes.


chromoplast

A plastid containing pigments other than chlorophyll, usually yellow and orange carotenoid pigments.


proteinoplast

A leucoplast in which protein is stored.


cyanelle

A plastid that contains unstacked, phycobilisome-bearing thylakoid membranes and is surrounded by a double membrane with a peptidoglycan layer in the intermembrane space between the two envelope membranes. Cyanelles are characteristic of algae in the class Glaucophyta, and may represent an ancestral form of plastid.


cell plate

The nascent cell membrane and cell wall structure that forms between two daughter nuclei near the center of a dividing plant cell. It develops at the equitorial region of the phragmoplast. It grows outwards to join with the lateral walls and form two daughter cells.


myelin sheath

An electrically insulating fatty layer that surrounds the axons of many neurons. It is an outgrowth of glial cells: Schwann cells supply the myelin for peripheral neurons while oligodendrocytes supply it to those of the central nervous system.


egg chorion

A protective, noncellular membrane that surrounds the eggs of various animals including insects and fish.


primary lysosome

A lysosome before it has fused with a vesicle or vacuole.


ascospore-type prospore nucleus

Any nucleus that is part of a ascospore-type prospore.


coated membrane

A single or double lipid bilayer with any of several different proteinaceous coats that can associate with membranes. Membrane coats include those formed by clathrin plus an adaptor complex, the COPI and COPII complexes.


bacterial-type flagellum filament

The long (approximately 20 nm), thin external structure of the bacterial-type flagellum, which acts as a propeller.


dendritic spine origin

The part of the dendritic spine neck where the spine arises from the dendritic shaft.


non-membrane-bounded organelle

Organized structure of distinctive morphology and function, not bounded by a lipid bilayer membrane. Includes ribosomes, the cytoskeleton and chromosomes.


archaeal-type flagellum

A non-membrane-bounded organelle superficially similar to a bacterial-type flagellum; they both consist of filaments extending outside the cell, and rotate to propel the cell, but the archaeal flagella (also called archaella) have a unique structure which lacks a central channel. Similar to bacterial type IV pilins, the archaeal flagellins (archaellins) are made with class 3 signal peptides and they are processed by a type IV prepilin peptidase-like enzyme. The archaellins are typically modified by the addition of N-linked glycans which are necessary for proper assembly and/or function.


cellular anatomical entity

A part of a cellular organism that is either an immaterial entity or a material entity with granularity above the level of a protein complex but below that of an anatomical system. Or, a substance produced by a cellular organism with granularity above the level of a protein complex.