exosome (RNase complex)

A ribonuclease complex that has 3-prime to 5-prime exoribonuclease activity and possibly endoribonuclease activity, producing 5-prime-phosphomonoesters. Participates in a multitude of cellular RNA processing and degradation events preventing nuclear export and/or translation of aberrant RNAs. Restricted to processing linear and circular single-stranded RNAs (ssRNA) only. RNAs with complex secondary structures may have to be unwound or pre-processed by co-factors prior to entering the complex, esp if the 3-prime end is structured.


EFF-1 complex

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A trimeric cell-cell fusion complex that serves as a scaffold for zippering up the extracellular domains, bringing the transmembrane segments into close proximity such that they can continue zippering within the two membranes into one. Two prefusion monomers cluster at the surface of adjacent cells. Parallel EFF-1 interactions occur across cells and a third monomer, which can come from either cell, adds on to make an intermediate, extended trimer.


glucosidase complex

A protein complex which is capable of glucosidase activity.


GTPase activator complex

A protein complex which is capable of GTPase activator activity.


mitochondrial degradosome

A mitochondrial protein complex with 3' to 5' exoribonuclease activity that participates in intron-independent turnover and processing of mitochondrial transcripts. In humans, the mitochondrial degradosome is a pentameric complex, and in yeast it exists as a heterodimer.


ribonuclease H2 complex

A protein complex that possesses ribonuclease H activity, in which the catalytic subunit is a member of the RNase H2 (or HII) class. For example, in Saccharomyces the complex contains Rnh201p, Rnh202p and Rnh203p.


mitochondrial ribonuclease P complex

A ribonuclease P complex located in the mitochondrion of a eukaryotic cell, where it catalyzes the 5' endonucleolytic cleavage of precursor tRNAs to yield mature tRNAs. The subunit composition of mitochondrial ribonuclease P complexes varies between species. The complex contains a single RNA molecule and a single protein molecule in yeast (PMID:12045094), but comprises three proteins and lacks an RNA component in humans.


reelin complex

An extracellular complex that binds lipoprotein receptors VLDLR and APOER2, cadherin-related neuronal receptors (CNRs) or alpha3beta1 integrin and induces various downstream, reelin-dependent, phosphorylation cascades. It ultimately affects polarization, differentiation, neuronal migration and layer formation in the embryonic brain and neuron growth, maturation, and synaptic activity in the postnatal and adult brain.


integrin alphav-beta6 complex

An integrin complex that comprises one alphav subunit and one beta6 subunit.


integrator complex

A protein complex that stably associates with the C-terminus of RNA polymerase II and mediates 3'-end processing of small nuclear RNAs generated by RNA polymerase II.


eukaryotic translation initiation factor 3 complex

A complex of several polypeptides that plays at least two important roles in protein synthesis: First, eIF3 binds to the 40S ribosome and facilitates loading of the Met-tRNA/eIF2.GTP ternary complex to form the 43S preinitiation complex. Subsequently, eIF3 apparently assists eIF4 in recruiting mRNAs to the 43S complex. The eIF3 complex contains five conserved core subunits, and may contain several additional proteins; the non-core subunits are thought to mediate association of the complex with specific sets of mRNAs.


type II site-specific deoxyribonuclease complex

A protein complex that functions as an endonuclease to cleave DNA at or near a specific recognition site, when that site is unmethylated. These complexes may be dimers or tetramers; it is also possible for the endonuclease to be in a complex with the corresponding methyltransferase that methylates the recognition site. DNA restriction systems such as this are used by bacteria to defend against phage and other foreign DNA that may enter a cell.


luminal surveillance complex

A multiprotein complex that recognizes ERAD-luminal misfolded substrates and brings them to the ubiquitination/extraction machinery. In yeast, this complex consists of Yos9p, Kar2p and Hrd3p proteins.


oligosaccharyltransferase II complex

An oligosaccharyltransferase (OST) complex that contains the seven polypeptides found in OST complex I, plus heterotrimeric Sec61alpha-beta-gamma. Of the three forms of mammalian OST complexes identified, the OSTII complex has intermediate affinity for ribosomes.


aminodeoxychorismate synthase complex

A heterodimeric protein complex that possesses 4-amino-4-deoxychorismate synthase activity.


RC-1 DNA recombination complex

A protein complex that contains DNA ligase III, DNA polymerase epsilon, a 5'-3' exonuclease, and the SMC1 and SMC2 proteins, and is involved in recombinational repair of deletions and gaps in DNA.


radial spoke 2

The radial spoke of each group of radial spokes, whether grouped as triplets or doublets, that is immediately distal to radial spoke 1 (RS1). Radial spoke 2 (RS2), similarly to RS1, is comprised of four domains: 1) a very short base anchored to the A microtubule, 2) an elongaged stalk, 3) a bifurcated neck, and 4) an orthogonal head. The base of RS2 is connected to the tail of the inner dynein arm c.


mitotic nuclear membrane microtubule tethering complex

A protein complex capable of interacting with the spindle pole body and the nuclear envelope, in order to embed the spindle pole body in the nuclear envelope at fusion sites of the inner and outer nuclear membrane.


integrin alphav-beta5 complex

An integrin complex that comprises one alphav subunit and one beta5 subunit.


integrin alphaE-beta7 complex

An integrin complex that comprises one alphaE subunit and one beta7 subunit.


eukaryotic translation initiation factor 2B complex

A multisubunit guanine nucleotide exchange factor which catalyzes the exchange of GDP bound to initiation factor eIF2 for GTP, generating active eIF2-GTP. In humans, it is composed of five subunits, alpha, beta, delta, gamma and epsilon.


Set1C/COMPASS complex

A conserved protein complex that catalyzes methylation of histone H3. In Saccharomyces the complex contains Shg1p, Sdc1p, Swd1p, Swd2p, Swd3p, Spp1p, Bre2p, and the trithorax-related Set1p; in mammals it contains the catalytic subunit (SETD1A or SETD1B), WDR5, WDR82, RBBP5, ASH2L/ASH2, CXXC1/CFP1, HCFC1 and DPY30.


Arp2/3 protein complex

A stable protein complex that contains two actin-related proteins, Arp2 and Arp3, and five novel proteins (ARPC1-5), and functions in the nucleation of branched actin filaments.


nuclear SCF ubiquitin ligase complex

A ubiquitin ligase complex, located in the nucleus, in which a cullin from the Cul1 subfamily and a RING domain protein form the catalytic core; substrate specificity is conferred by a Skp1 adaptor and an F-box protein. SCF complexes are involved in targeting proteins for degradation by the proteasome. The best characterized complexes are those from yeast and mammals (with core subunits named Cdc53/Cul1, Rbx1/Hrt1/Roc1).


IgY immunoglobulin complex

A protein complex composed of two identical immunoglobulin heavy chains of the IgY isotype and two identical immunoglobulin light chains, held together by disulfide bonds. An IgY immunoglobulin complex may be embedded in the plasma membrane or present in the extracellular space, in mucosal areas or other tissues, or circulating in the blood or lymph.


interleukin-27 complex

A protein complex that is composed of an interleukin-27p28 subunit (product of the IL27 gene) and an EBI3 subunit and is secreted into the extracellular space.


lipopolysaccharide receptor complex

A multiprotein complex that consists of at least three proteins, CD14, TLR4, and MD-2, each of which is glycosylated and which functions as a lipopolysaccharide (LPS) receptor that primes the innate immune response against bacterial pathogens.


HOPS complex

A multimeric protein complex that associates with the vacuolar membrane, late endosomal (multivesicular body) and lysosomal membranes. HOPS is a tethering complex involved in vesicle fusion.


inhibin complex

Heterodimeric hormone composed of an inhibin alpha subunit complexed with either an inhibin beta-A subunit, to form inhibin A, or an inhibin beta-B subunit, to form inhibin B.


laminin-1 complex

A laminin complex composed of alpha1, beta1 and gamma1 polypeptide chains.


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).


NADH dehydrogenase complex

An integral membrane complex that possesses NADH oxidoreductase activity. The complex is one of the components of the electron transport chain. It catalyzes the transfer of a pair of electrons from NADH to a quinone.


PET complex

A protein complex that is composed of at least EXD1, TDRD12 and some PIWI protein. The complex is required for MILI slicing-triggered biogenesis and loading of MIWI2 piRNAs.


G protein-coupled receptor dimeric complex

A protein complex that contains two G protein-coupled receptors.


nuclear pore nuclear basket

A filamentous, cage-like assembly on the nuclear face of the nuclear pore complex (NPC). In S. cerevisiae, Mlp1p and Mlp2p are two major components of the NPC nuclear basket. In vertebrates, Tpr is a major component.


icosahedral viral capsid, neck fiber

A fiber attached to the neck at the base of some icosahedral viral capsids.


viral capsid, turret

A turret-like appendage formed at the vertices of an icosahedral capsid.


viral capsid, fiber

A type of capsid decoration composed of fiber structures.


root hair

A long, thin projection from a root epidermal cell that contains F-actin and tubulin, and a cell wall.


rough endoplasmic reticulum membrane

The lipid bilayer surrounding the rough endoplasmic reticulum.


equatorial microtubule organizing center

A microtubule organizing center formed by a band of gamma-tubulin that is recruited to a circumferential band of F-actin at the midpoint of a cell and which nucleates microtubules from the cell division site at the end of mitosis.


left nucleus

One of the two nuclei found in Giardia species (trophozoite stage). It is located on the left side of the cell when viewed from the dorsal side.


telopode

A telopode is a plasma membrane bounded cell projection that is present on a telocyte and is tens to hundreds of microns long. Telopodes form a labyrinthine system communicating through gap junctions.


A axonemal microtubule

A complete microtubule with 13 protofilaments that fuses with an incomplete microtubule called B tubule (containing 10 protofilaments only) to form an axonemal outer doublet. Inner and outer dynein arms, as well as the radial spoke, are attached to the A tubule.


supramolecular complex

A cellular component that consists of an indeterminate number of proteins or macromolecular complexes, organized into a regular, higher-order structure such as a polymer, sheet, network or a fiber.


lamin filament

Any of a group of intermediate-filament proteins that form the fibrous matrix on the inner surface of the nuclear envelope. They are classified as lamins A, B and C.


skeletal muscle myofibril

A myofibril of a skeletal muscle fiber.


dendritic microtubule

Any microtubule in a dendrite, a neuron projection.


type III intermediate filament

A type of intermediate filament, typically made up of one or more of the proteins vimentin, desmin, glial fibrillary acidic protein (GFAP), and peripherin. Unlike the keratins, the type III proteins can form both homo- and heteropolymeric IF filaments.


fibronectin fibril

A supramolecular fiber formed from fibronectin molecules. The fibrils are 5 to 25nm in diameter and can form branched meshworks.


intraconoid microtubule

A microtubule located such that it threads through the conoid and projects through the polar ring.


supramolecular polymer

A polymeric supramolecular structure.


astral microtubule

Any of the spindle microtubules that radiate in all directions from the spindle poles and are thought to contribute to the forces that separate the poles and position them in relation to the rest of the cell.


kinetochore microtubule

Any of the spindle microtubules that attach to the kinetochores of chromosomes by their plus ends, and maneuver the chromosomes during mitotic or meiotic chromosome segregation.


post-anaphase array microtubule

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


mitotic spindle polar microtubule

Any of the mitotic spindle microtubules that come from each pole and overlap at the spindle midzone.


contractile fiber

Fibers, composed of actin, myosin, and associated proteins, found in cells of smooth or striated muscle.


smooth muscle contractile fiber

The contractile fiber of smooth muscle cells.


meiotic spindle astral microtubule

Any of the meiotic spindle microtubules that radiate in all directions from the spindle poles and are thought to contribute to the forces that separate the poles and position them in relation to the rest of the cell.


polymeric cytoskeletal fiber

A component of the cytoskeleton consisting of a homo or heteropolymeric fiber constructed from an indeterminate number of protein subunits.


spindle microtubule

Any microtubule that is part of a mitotic or meiotic spindle; anchored at one spindle pole.


actomyosin contractile ring actin filament

Any actin filament that is part of a actomyosin contractile ring.


polar microtubule

Any of the spindle microtubules that come from each pole and overlap at the spindle midzone. This interdigitating structure consisting of antiparallel microtubules is responsible for pushing the poles of the spindle apart.


subpellicular microtubule

Singlet microtubule that lie underneath the inner membrane pellicle complex and emanate from the basal ring of the conoid.


microfibril

Extracellular matrix components occurring independently or along with elastin. Thought to have force-bearing functions in tendon. In addition to fibrillins, microfibrils may contain other associated proteins.


cortical microtubule

Arrays of microtubules underlying and connected to the plasma membrane in the cortical cytosol.


cardiac myofibril

A cardiac myofibril is a myofibril specific to cardiac muscle cells.


actin filament of cell cortex of cell tip

Any actin filament that is part of a cell cortex of cell tip.


cytoplasmic microtubule

Any microtubule in the cytoplasm of a cell.


paraflagellar rod

A large lattice-like axial structure found in some flagellated protists which extends alongside the axoneme. Protein components of the paraflagellar rod are likely implicated, among other, in adenine nucleotide signalling and metabolism, and in calcium signalling.


mastigoneme

A hair-like structure covering the flagella found in some algae (heterokonts and cryptophytes). It is approximately 15 nm in diameter, and usually consist of a tubular shaft that itself terminates in smaller hairs. It is composed of glycoproteins and, likely, carbohydrates. Mastigonemes may assist in locomotion by increasing the surface area of a flagellum.


C2 axonemal microtubule

One of two microtubules present in the axonemal central pair. It is distinguishable from the C1 axonemal microtubule (also called C1 tubule) by the presence of differing protein components of the projections.


actin filament

A filamentous structure formed of a two-stranded helical polymer of the protein actin and associated proteins. Actin filaments are a major component of the contractile apparatus of skeletal muscle and the microfilaments of the cytoskeleton of eukaryotic cells. The filaments, comprising polymerized globular actin molecules, appear as flexible structures with a diameter of 5-9 nm. They are organized into a variety of linear bundles, two-dimensional networks, and three dimensional gels. In the cytoskeleton they are most highly concentrated in the cortex of the cell just beneath the plasma membrane.


collagen beaded filament

A supramolecular assembly of collagen trimers with a 'beads on a string'-like structure.


outer dense fiber

A supramolecular fiber found in the flagella of mammalian sperm that surrounds the nine microtubule doublets. These dense fibers are stiff and noncontractile. In human, they consist of about 10 major and at least 15 minor proteins, where all major proteins are ODF1, ODF2 or ODF2-related proteins.


supramolecular fiber

A polymer consisting of an indefinite number of protein or protein complex subunits that have polymerised to form a fiber-shaped structure.


horsetail-astral microtubule array

An array of astral microtubules that emanates from the spindle pole body during meiosis and facilitates horsetail nuclear movement.


intranuclear rod

A macromolecular fiber consisting of actin and cofilin that is formed in the nucleus as a consequence of chemical or mechanical stress conditions.


mitotic spindle microtubule

Any microtubule that is part of a mitotic spindle; anchored at one spindle pole.


mitotic spindle astral microtubule

Any of the mitotic spindle microtubules that radiate in all directions from the spindle poles and are thought to contribute to the forces that separate the poles and position them in relation to the rest of the cell.


aster

An array of microtubules emanating from a spindle pole MTOC that do not connect to kinetochores.


neurofilament

A type of intermediate filament found in the core of neuronal axons. Neurofilaments are heteropolymers composed of three type IV polypeptides: NF-L, NF-M, and NF-H (for low, middle, and high molecular weight). Neurofilaments are responsible for the radial growth of an axon and determine axonal diameter.


glial filament

An intermediate filament composed of glial fibrillary acidic protein (GFAP) and found in astrocytes.


myofibril

The contractile element of skeletal and cardiac muscle; a long, highly organized bundle of actin, myosin, and other proteins that contracts by a sliding filament mechanism.


mitotic spindle kinetochore microtubule

Any of the mitotic spindle microtubules that attach to the kinetochores of chromosomes by their plus ends, and maneuver the chromosomes during mitotic chromosome segregation.


axonemal microtubule

A microtubule in the axoneme of a eukaryotic cilium or flagellum; an axoneme contains nine modified doublet microtubules, which may or may not surround a pair of single microtubules.


cytoophidium

A subcellular filamentary structure where CTP synthase is compartmentalized in a range of organisms including bacteria, yeast, fruit fly, rat and human.


B axonemal microtubule

An incomplete microtubule containing 10 protofilaments that fuses with a complete microtubule called A tubule (containing 13 protofilaments) to form an axonemal outer doublet.


cortical microtubule, transverse to long axis

Arrays of microtubules underlying and connected to the plasma membrane, in the cortical cytosol, oriented mainly with their axes transverse to the long axis of the cell (and root in plants). In plants it influences the direction of cellulose microfibril deposition.


C1 axonemal microtubule

One of two microtubules present in the axonemal central pair. It is distinguishable from the C2 axonemal microtubule (also called C2 tubule) by the presence of differing protein components of the projections.


nuclear microtubule

Any microtubule in the nucleus of a cell.


trichome papilla

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


investment cone

A cytoskeletal part that consists of a microfilament-rich cone that forms round each nucleus in a spermatogenic cyst and translocates the length of the cyst during sperm individualization.


chiasma

A connection formed between chromatids, visible during meiosis, thought to be the point of the interchange involved in crossing-over.


neuromuscular junction of skeletal muscle fiber

A neuromuscular junction in which the target muscle cell is a skeletal muscle fiber.


yolk plasma

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


germ tube septin cap

A faint structure formed of septins found at the leading edge of growth in germ tubes of fungal cells growing filamentously. This cap of septins colocalizes with a region of the plasma membrane that is rich in ergosterol.


actin cytoskeleton of dendritic spine

The actin cytoskeleton that is part of a dendritic spine.


hyphae septin collar

A septin collar in pathogenic fungi involved in the constriction of hyphae at the plant plasmodesma enabling penetration of an adjacent cell.


prospore septin filament array

Arrays of septin filaments, or bars, found in a series of filamentous structures; observed in the prospore membrane during spore formation.


septin filament array

Arrays of septin filaments, or bars, found in a series of filamentous structures. Such structures have been observed in the prospore membrane during spore formation in S. cerevisiae and in the chlamydospore membrane during chlamydospore formation in C. albicans.


postsynaptic cytoskeleton

The portion of the cytoskeleton contained within the postsynapse.


postsynaptic septin cytoskeleton

The portion of the septin cytoskeleton contained within the postsynapse.


mating projection septin ring

A septin ring, i.e. a ring-shaped structure composed of septins and septin-associated proteins, located at the neck of a shmoo (mating projection). The septin ring in the neck of a shmoo may act as a barrier to localize mating factors in the shmoo tip.


postsynaptic intermediate filament cytoskeleton

The intermediate filament cytoskeleton that is part of a postsynapse.


septin ring

A tight ring-shaped structure that forms in the division plane at the site of cytokinesis; composed of members of the conserved family of filament-forming proteins called septins as well as septin-associated proteins. This type of septin structure is observed at the bud neck of budding fungal cells, at the site of cell division in animal cells, at the junction between the mother cell and a pseudohyphal projection, and also within hyphae of filamentous fungi at sites where a septum will form.


septin collar

A tubular, hourglass-shaped structure composed of highly ordered arrays of septin filaments; in budding yeast cells, the septin collar forms from the initial septin ring by expanding into the daughter cell.


postsynaptic actin cytoskeleton

The actin cytoskeleton that is part of a postsynapse.


germ tube septin ring

A tight ring-shaped structure that forms in the division plane within the germ tube of filamentous fungi at sites where a septum will form; composed of septins as well as septin-associated proteins.


split septin rings

A pair of rings that flank the site of cell division, formed by splitting of the septin ring (or collar) prior to cytokinesis; this double ring structure is thought to trap proteins needed for cytokinesis or the formation of the new membrane or cell wall between the two septin rings. Split septin rings are known to occur in budding yeast cells and probably occur in other cell types as well.


septin cytoskeleton

The part of the cytoskeleton (the internal framework of a cell) composed of septins and associated proteins. Includes septin cytoskeleton-associated complexes.


presynaptic actin cytoskeleton

The actin cytoskeleton that is part of a presynapse.


prospore septin ring

A tight ring-shaped structure that forms in the division plane at the site of cytokinesis in a prospore; composed of septins as well as septin-associated proteins.


chlamydospore septin filament array

Arrays of septin filaments, or bars, found in a series of filamentous structures. Observed in the chlamydospore membrane during chlamydospore formation.


neurofilament cytoskeleton

Intermediate filament cytoskeletal structure that is made up of neurofilaments. Neurofilaments are specialized intermediate filaments found in neurons.


hyphal septin cap

A faint structure formed of septins found at the leading edge of growth in hyphae of fungal cells growing filamentously. This cap of septins colocalizes with a region of the plasma membrane that is rich in ergosterol.


septin cap

A faint structure formed of septins found at the leading edge of growth in germ tubes and hyphae in fungal cells growing filamentously. This cap of septins colocalizes with a region of the plasma membrane that is rich in ergosterol.


pseudohyphal septin ring

A tight ring-shaped structure that forms in the division plane at the junction between the mother cell and a pseudohyphal projection; composed of septins as well as septin-associated proteins.


presynaptic cytoskeleton

The portion of the cytoskeleton contained within the presynapse.


microtubule cytoskeleton

The part of the cytoskeleton (the internal framework of a cell) composed of microtubules and associated proteins.


cellular bud neck septin ring

A ring-shaped structure that forms at the site of cytokinesis in the bud neck of a budding cell; composed of members of the conserved family of filament forming proteins called septins as well as septin-associated proteins. In S. cerevisiae, this structure forms at the time of bud emergence and the septins show a high rate of exchange.


perinuclear theca

A condensed cytoplasmic structure that covers the nucleus of mammalian spermatozoa except for a narrow zone around the insertion of the tail. It shows two distinct regions, a subacrosomal layer and, continuing caudally beyond the acrosomic system, the postacrosomal sheath. The perinuclear theca has been considered a cytoskeletal scaffold responsible for maintaining the overall architecture of the mature sperm head; however, recent studies indicate that the bulk of its constituent proteins are not traditional cytoskeletal proteins but rather a variety of cytosolic proteins.


presynaptic intermediate filament cytoskeleton

The intermediate filament cytoskeleton that is part of a presynapse.


cytoskeleton of dendritic spine

The portion of the cytoskeleton that lies within a dendritic spine. The actin component of this cytoskeleton is involved in spine head remodeling in response to postsynaptic signalling.


actin cytoskeleton

The part of the cytoskeleton (the internal framework of a cell) composed of actin and associated proteins. Includes actin cytoskeleton-associated complexes.


intermediate filament cytoskeleton

Cytoskeletal structure made from intermediate filaments, typically organized in the cytosol as an extended system that stretches from the nuclear envelope to the plasma membrane. Some intermediate filaments run parallel to the cell surface, while others traverse the cytosol; together they form an internal framework that helps support the shape and resilience of the cell.


hyphal septin ring

A tight ring-shaped structure that forms in the division plane within hyphae of filamentous fungi at sites where a septum will form; composed of septins as well as septin-associated proteins.


cellular bud neck split septin rings

Two separate septin rings that are formed from the septin collar at the time of cytokinesis in cells that divide by budding. These two rings are thought to delineate a special compartment in which factors involved in cytokinesis are concentrated.


spectrin-associated cytoskeleton

The part of the cytoskeleton composed of spectrin, protein 4.1 and ankyrin. Spectrin-associated cytoskeleton is associated with the plasma membrane.


medial cortex septin ring

A ring-shaped structure that forms at the medial cortex of a symmetrically dividing cell at the onset of cytokinesis; composed of members of the conserved family of filament forming proteins called septins as well as septin-associated proteins.


The portion of the spectrin-associated cytoskeleton contained within the postsynapse.


phagophore assembly site

Punctate structures proximal to the endoplasmic reticulum which are the sites where the Atg machinery assembles upon autophagy induction.


dinoflagellate apical horn

A horn-shaped dinoflagellate apex found in thecate species.


host cell endocytic vesicle membrane

The lipid bilayer surrounding a host cell endocytic vesicle.


esterosome membrane

The lipid bilayer surrounding an esterosome. This membrane has characteristics of rough endoplasmic reticulum (RER) membranes.


Golgi medial cisterna

The middle Golgi cisterna (or cisternae).


stress fiber

A contractile actin filament bundle that consists of short actin filaments with alternating polarity, cross-linked by alpha-actinin and possibly other actin bundling proteins, and with myosin present in a periodic distribution along the fiber.


chromoplast inner membrane

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


chromoplast membrane

Either of the lipid bilayers that surround a chromoplast and form the chromoplast envelope.


H zone

A relatively pale zone traversing the center of the A band of a sarcomere, visible in relaxed muscle fibers; consists of the central portion of thick (myosin) filaments that are not overlapped by thin (actin) filaments.


amyloplast

A plastid whose main function is to synthesize and store starch.


secondary cell wall

A plant cell wall that is no longer able to expand and so does not permit growth. Secondary cell walls contain less pectin that primary cell walls. The secondary cell is mostly composed of cellulose and is strengthened with lignin.


extrinsic component of periplasmic side of plasma membrane

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


hippocampal mossy fiber to CA3 synapse

One of the giant synapses that form between the mossy fiber axons of dentate gyrus granule cells and the large complex spines of CA3 pyramidal cells. It consists of a giant bouton known as the mossy fiber expansion, synapsed to the complex, multiheaded spine (thorny excresence) of a CA3 pyramidal cell.


left caudal basal body

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


centrosome

A structure 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.


spindle pole centrosome

A centrosome from which one pole of a mitotic or meiotic spindle is organized.


viral capsid, minor subunit

The part of the viral capsid that comprises the less common capsomere type. For example, in a T=3 icosahedral capsid, which is composed of 12 pentameric and 20 hexameric capsomeres, the pentameric capsomeres are minor subunits.


viral capsid, major subunit

The part of the viral capsid that comprises the most common capsomere type. For example, in a T=3 icosahedral capsid, which is composed of 12 pentameric and 20 hexameric capsomeres, the hexameric capsomeres are major subunits.


sexual spore wall

A specialized envelope lying outside the cell membrane of a spore derived from a product of meiosis.


spore wall

The specialized envelope lying outside the cell membrane of a spore.


asexual spore wall

A specialized envelope lying outside the cell membrane of a spore derived from an asexual process. Examples of this process are found in bacterial and fungal species.


ascospore wall

The specialized cell wall of the ascospore (spore), which is the product of meiotic division. Examples of this component are found in Fungi.


endospore external encapsulating structure

The structures that lie outside the inner membrane and surround the entire endospore; consists of a peptidoglycan-containing inner layer (the endospore cortex) surrounded by a multilayered proteinaceous coat. An exosporium may be present as an extreme outer layer.


cellular bud

A protuberance from a cell of an organism that reproduces by budding, which will grow larger and become a separate daughter cell after nuclear division, cytokinesis, and cell wall formation (when appropriate). The daughter cell may completely separate from the mother cell, or the mother and daughter cells may remain associated.


trans-Golgi network

The network of interconnected tubular and cisternal structures located within the Golgi apparatus on the side distal to the endoplasmic reticulum, from which secretory vesicles emerge. The trans-Golgi network is important in the later stages of protein secretion where it is thought to play a key role in the sorting and targeting of secreted proteins to the correct destination.


thylakoid membrane

The pigmented membrane of any thylakoid.


photosynthetic membrane

A membrane enriched in complexes formed of reaction centers, accessory pigments and electron carriers, in which photosynthetic reactions take place.


cyanelle thylakoid membrane

The lipid bilayer membrane of any thylakoid within a cyanelle.


prothylakoid membrane

The membrane of prothylakoids, underdeveloped thylakoids found in etioplasts, lacking competent photosynthetic membranes.


chloroplast thylakoid membrane

The pigmented membrane of a chloroplast thylakoid. An example of this component is found in Arabidopsis thaliana.


plasma membrane-derived chromatophore membrane

The lipid bilayer associated with a plasma membrane-derived chromatophore; surrounds chromatophores that form complete vesicles.


plasma membrane-derived thylakoid membrane

The pigmented membrane of a plasma membrane-derived thylakoid.


organellar chromatophore thylakoid membrane

The lipid bilayer membrane of any thylakoid within an organellar chromatophore.


plastid thylakoid membrane

The lipid bilayer membrane of any thylakoid within a plastid.


infected host cell surface knob

Protrusion that develops in the plasma membrane of a parasitized erythrocyte. An example of this component is found in Plasmodium species.


microvillar actin bundle

A parallel bundle of actin filaments at the core of a microvillus.


parallel actin filament bundle

An actin filament bundle in which the filaments are tightly packed (approximately 10-20 nm apart) and oriented with the same polarity.


formin-nucleated actin cable

An actin filament bundle that consists of short filaments organized into bundles of uniform polarity, and is nucleated by formins. In fungal cells, myosin motors transport cargo along actin cables toward sites of polarized cell growth; actin cables may play a similar role in pollen tube growth.


actin filament bundle of filopodium

A parallel bundle of actin filaments that is part of filopodium. Filaments are oriented such that the plus (barbed) ends are at the tip of the protrusion, capped by a tip complex.


actin filament bundle of stereocilium

A bundle of hundreds of cross-linked actin filaments (an actin cable), that is the supporting structure of a stereocilium. Filaments are oriented such that the the plus (barbed) ends are at the tip of the protrusion and are capped by a tip complex which bridges to the plasma membrane.


actin filament bundle of actin-based cell projection

A bundle of cross-linked actin filaments that is part of an actin-based cell protrusion, in which filaments are oriented such that the plus (barbed) ends are at the tip of the protrusion, capped by a tip complex which stabilizes the filaments.


ficolin-1-rich granule membrane

The lipid bilayer surrounding a ficolin-1-rich granule.


cytoplasmic vesicle membrane

The lipid bilayer surrounding a cytoplasmic vesicle.


clathrin-coated phagocytic vesicle membrane

The lipid bilayer surrounding a clathrin-coated phagocytic vesicle.


endosome membrane

The lipid bilayer surrounding an endosome.


early endosome membrane

The lipid bilayer surrounding an early endosome.


inter-Golgi transport vesicle membrane

The lipid bilayer surrounding a vesicle transporting substances within the Golgi.


coated vesicle membrane

The lipid bilayer surrounding a coated vesicle.


outer acrosomal membrane

The acrosomal membrane region that underlies the plasma membrane of the sperm. This membrane fuses with the sperm plasma membrane as part of the acrosome reaction.


chromaffin granule membrane

The lipid bilayer surrounding a chromaffin granule, a specialized secretory vesicle found in the cells of adrenal glands and various other organs, which is concerned with the synthesis, storage, metabolism, and secretion of epinephrine and norepinephrine.


clathrin-coated endocytic vesicle membrane

The lipid bilayer surrounding a clathrin-coated endocytic vesicle.


transport vesicle membrane

The lipid bilayer surrounding a transport vesicle.


Golgi-associated vesicle membrane

The lipid bilayer surrounding a vesicle associated with the Golgi apparatus.


specific granule membrane

The lipid bilayer surrounding a specific granule, a granule with a membranous, tubular internal structure, found primarily in mature neutrophil cells. Most are released into the extracellular fluid. Specific granules contain lactoferrin, lysozyme, vitamin B12 binding protein and elastase.


postsynaptic early endosome membrane

The lipid bilayer surrounding a postsynaptic early endosome.


ER to Golgi transport vesicle membrane

The lipid bilayer surrounding a vesicle transporting substances from the endoplasmic reticulum to the Golgi.


organellar chromatophore inner membrane

The inner, i.e. lumen-facing, of the two lipid bilayers surrounding an organellar chromatophore.


secretory granule membrane

The lipid bilayer surrounding a secretory granule.


postsynaptic endosome membrane

The lipid bilayer surrounding a postsynaptic endosome.


phagolysosome vesicle membrane

The lipid bylayer surrounding a phagolysosome.


macropinosome membrane

The lipid bilayer surrounding a macropinosome.


lamellar body membrane

The lipid bilayer surrounding a lamellar body. A lamellar body is a membrane-bounded organelle, specialized for the storage and secretion of various substances (surfactant phospholipids, glycoproteins and acid phosphates) which are arranged in the form of tightly packed, concentric, membrane sheets or lamellae. Has some similar properties to, but is distinct from, a lysosome.


platelet dense granule membrane

The lipid bilayer surrounding the platelet dense granule.


organellar chromatophore membrane

Either of the lipid bilayers that surround an organellar chromatophore.


presynaptic endosome membrane

The lipid bilayer surrounding a presynaptic endosome.


postsynaptic recycling endosome membrane

The lipid bilayer surrounding a postsynaptic recycling endosome.


azurophil granule membrane

The lipid bilayer surrounding an azurophil granule, a primary lysosomal granule found in neutrophil granulocytes that contains a wide range of hydrolytic enzymes and is released into the extracellular fluid.


recycling endosome membrane

The lipid bilayer surrounding a recycling endosome.


trans-Golgi network transport vesicle membrane

The lipid bilayer surrounding a vesicle transporting substances between the trans-Golgi network and other parts of the cell.


synaptic vesicle membrane

The lipid bilayer surrounding a synaptic vesicle.


platelet alpha granule membrane

The lipid bilayer surrounding the platelet alpha granule.


dense core granule membrane

The lipid bilayer surrounding a dense core granule.


endocytic vesicle membrane

The lipid bilayer surrounding an endocytic vesicle.


peribacteroid membrane

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


COPI-coated vesicle membrane

The lipid bilayer surrounding a COPI-coated vesicle.


alveolar lamellar body membrane

The lipid bilayer surrounding an alveolar lamellar body, a specialized secretory organelle found in type II pneumocytes and involved in the synthesis, secretion, and reutilization of pulmonary surfactant.


early phagosome membrane

The lipid bilayer surrounding an early phagosome.


tertiary granule membrane

The lipid bilayer surrounding a tertiary granule.


endolysosome membrane

The lipid bilayer surrounding an endolysosome. An endolysosome is a transient hybrid organelle formed by fusion of a late endosome with a lysosome.


aleurone grain membrane

The lipid bilayer surrounding an aleurone grain.


epidermal lamellar body membrane

The lipid bilayer surrounding an epidermal lamellar body, a specialized secretory organelle found in keratinocytes and involved in the formation of an impermeable, lipid-containing membrane that serves as a water barrier and is required for correct skin barrier function.


gut granule membrane

The membrane of a gut granule, a lysosome-related organelle contained within the intestinal cells of the nematode C. elegans.


multivesicular body membrane

The lipid bilayer surrounding a multivesicular body.


clathrin-sculpted monoamine transport vesicle membrane

The lipid bilayer surrounding a clathrin-sculpted monoamine transport vesicle.


merozoite dense granule membrane

The lipid bilayer surrounding a dense granule of the type found in apicomplexan parasites.


inner acrosomal membrane

The acrosomal membrane region that underlies the acrosomal vesicle and is located toward the sperm nucleus. This region is responsible for molecular interactions allowing the sperm to penetrate the zona pellucida and fuses with the egg plasma membrane.


late endosome membrane

The lipid bilayer surrounding a late endosome.


clathrin-sculpted glutamate transport vesicle membrane

The lipid bilayer surrounding a clathrin-sculpted glutamate transport vesicle.


multivesicular body, internal vesicle membrane

The lipid bilayer surrounding a multivesicular body internal vesicle.


organellar chromatophore outer membrane

The outer, i.e. cytoplasm-facing, of the two lipid bilayers surrounding an organellar chromatophore.


Golgi to ER transport vesicle membrane

The lipid bilayer surrounding a vesicle transporting substances from the Golgi to the ER.


phagolysosome membrane

The lipid bilayer surrounding a phagolysosome.


exocytic vesicle membrane

The lipid bilayer surrounding an exocytic vesicle.


clathrin-sculpted gamma-aminobutyric acid transport vesicle membrane

The lipid bilayer surrounding a clathrin-sculpted gamma-aminobutyric acid transport vesicle.


acrosomal membrane

The membrane that surrounds the acrosomal lumen. The acrosome is a special type of lysosome in the head of a spermatozoon that contains acid hydrolases and is concerned with the breakdown of the outer membrane of the ovum during fertilization.


rod photoreceptor disc membrane

Stack of disc membranes located inside a rod photoreceptor outer segment, and containing densely packed molecules of rhodopsin photoreceptor proteins that traverse the lipid bilayer. It is thought that rod disc membranes arise as evaginations of the ciliary membrane near the base of the outer segment, which then become completely separated from the ciliary membrane, during the development of the rod outer segment.


contractile vacuolar membrane

The lipid bilayer surrounding the contractile vacuole.


Cvt vesicle membrane

Either of the two lipid bilayers surrounding a Cvt vesicle, a vesicle that functions in the cytoplasm-to-vacuole targeting (Cvt) pathway.


phagocytic vesicle membrane

The lipid bilayer surrounding a phagocytic vesicle.


chitosome membrane

The lipid bilayer surrounding a chitosome.


clathrin-coated vesicle membrane

The lipid bilayer surrounding a clathrin-coated vesicle.


foot layer

The inner layer of the ectexine.


germ plasm

Differentiated cytoplasm associated with a pole of an oocyte, egg or early embryo that will be inherited by the cells that will give rise to the germ line.


cytoplasmic periphery of the nuclear pore complex

Cytoplasm situated in close proximity to a nuclear pore complex.


cerebellar Golgi cell to granule cell synapse

A synapse formed by a cerebellar Golgi cell synapsing on to a cerebellar granule cell.


presynaptic periactive zone

A region that surrounds the active zone of the presynaptic plasma membrane, and is specialized for the control of synaptic development.


multiple synapse bouton, contacting single dendrite

A single axon terminal bouton making contact onto two or more dendritic spines protruding from the same dendrite.


tripartite attachment complex

A three-part cytoskeletal structure in kinetoplastid species linking mitochondrial DNA organised in a kinetoplast through the mitochondrial membranes to the basal body.


dense body

An electron dense body which may contain granules.


viral capsid, internal space

The region of a virus contained within the capsid shell, and usually containing the viral genome and accessory proteins.


primary endosperm nucleus

Nucleus resulting from the fusion of the male gamete and two polar nuclei in the central cell of the embryo sac.


actin cortical patch

An endocytic patch that consists of an actin-containing structure found at the plasma membrane in cells; formed of networks of branched actin filaments that lie just beneath the plasma membrane and assemble, move, and disassemble rapidly. An example of this is the actin cortical patch found in Saccharomyces cerevisiae.


endocytic patch

The part of the cell cortex consisting of an aggregation of proteins that will give rise to an endocytic vesicle.


flagella connector

A mobile transmembrane junction at the tip of the flagellum of some kinetoplastid species linking the tip of a new growing flagellum to an older flagellum.


macromolecule

A macromolecule is a molecule of high relative molecular mass, the structure of which essentially comprises the multiple repetition of units derived, actually or conceptually, from molecules of low relative molecular mass.


polypeptide

A peptide containing ten or more amino acid residues.


biomacromolecule

A macromolecule formed by a living organism.


cellulose microfibril

A microfibril composed of cellulose arranged in orthogonal layers. Cellulose is a straight chain polysaccharide composed of B(14) linked glucose subunits. It is a major component of plant cell walls. Higher plant microfibrils are about 10nm in diameter and extremely long in relation to their width. The cellulose molecules are oriented parallel to the long axis of the microfibril in a paracrystalline array, which provides great tensile strength. The microfibrils are held in place by the wall matrix and their orientation is closely controlled by the cell.


neck portion of tanycyte

Elongated portion of a tanycyte that sticks into the periventricular layer of neuropil where it appears to contact a blood vessel; characterized by numerous cytoplasmic extensions. A tanycyte is a specialized elongated ventricular ependymal cell that has processes that extend to the outer, or pial, surface of the CNS.


lamellipodium membrane

The portion of the plasma membrane surrounding a lamellipodium.


chloroplast chromosome

A circular DNA molecule containing chloroplast encoded genes.


plastid chromosome

A circular DNA molecule containing plastid encoded genes.


somatic spine

Spine emanating from the cell soma of a neuron.


glycinergic synapse

A synapse that uses glycine as a neurotransmitter.


platelet dense tubular network

A network of membrane-bounded compartments found in blood platelets, where they regulate platelet activation by sequestering or releasing calcium. The dense tubular network exists as thin elongated membranes in resting platelets, and undergoes a major ultrastructural change, to a rounded vesicular form, upon addition of thrombin.


cytoplasmic replication fork

The Y-shaped region of a cytoplasmic replicating DNA molecule, resulting from the separation of the DNA strands and in which the synthesis of new strands takes place. Also includes associated protein complexes.


host cell lysosomal membrane

The lipid bilayer surrounding the host cell lysosome and separating its contents from the host cell cytoplasm.


cellular birth scar

Crater-like ring of chitinous scar tissue located on the surface of the daughter cell, in budding fungi, at the site of separation from the mother cell. It is formed after the newly emerged daughter cell separates, thereby marking the site of cytokinesis and septation.


cell cortex of growing cell tip

Any cell cortex that is part of a growing cell tip.


posterior cell cortex

The region that lies just beneath the plasma membrane in the part of a cell that is closest to the posterior as defined by the developing, or existing, anterior/posterior axis.


dendritic spine cytoplasm

The region of the neuronal cytoplasm located in dendritic spines.


lateral cell cortex

The region directly beneath the plasma membrane of the lateral portion of the cell.


pole plasm

Differentiated cytoplasm associated with a pole (animal, vegetal, anterior, or posterior) of an oocyte, egg or early embryo.


apical cortex

The region that lies just beneath the plasma membrane on the apical edge of a cell.


presynaptic endocytic zone cytoplasmic component

The cytoplasmic component of the presynaptic endocytic zone.


dendrite cytoplasm

All of the contents of a dendrite, excluding the surrounding plasma membrane.


equatorial cell cortex

The region of the cell cortex in a mitotically dividing cell that flanks the central spindle and corresponds to the site of actomyosin ring formation that results in cleavage furrow formation and ingression.


presynaptic active zone cytoplasmic component

A specialized region below the presynaptic membrane, characterized by electron-dense material, a specialized cytoskeletal matrix and accumulated (associated) synaptic vesicles.


cell cortex of cell tip

The region directly beneath the plasma membrane at the cell tip. The cell tip is the region at either end of the longest axis of a cylindrical or elongated cell.


cell cortex region

The complete extent of cell cortex that underlies some some region of the plasma membrane.


medial cortex

A medial cortical band overlaying the nucleus which acts as a landmark for contractile ring positioning and plays a role in cell cycle regulation.


cytoplasmic region

Any (proper) part of the cytoplasm of a single cell of sufficient size to still be considered cytoplasm.


ooplasm

The cytoplasm of an ovum.


postsynaptic endocytic zone cytoplasmic component

The cytoplasmic component of the postsynaptic endocytic zone.


cell leading edge cell cortex

The cell cortex of the leading edge of a cell.


apicomedial cortex

The region that lies just beneath the plasma membrane in the middle of the apical edge of a cell.


basal cortex

The region that lies just beneath the plasma membrane on the basal edge of a cell.


plasma membrane bounded cell projection cytoplasm

All of the contents of a plasma membrane bounded cell projection, excluding the plasma membrane surrounding the projection.


anterior cell cortex

The region that lies just beneath the plasma membrane in the part of a cell that is closest to the anterior as defined by the developing, or existing, anterior/posterior axis.


ciliary plasm

All of the contents of a cilium, excluding the plasma membrane surrounding the cilium.


cell cortex

The region of a cell that lies just beneath the plasma membrane and often, but not always, contains a network of actin filaments and associated proteins.


neuron projection cytoplasm

All of the contents of a plasma membrane bounded neuron projection, excluding the plasma membrane surrounding the projection.


sarcoplasm

The cytoplasm of a muscle cell; includes the sarcoplasmic reticulum.


cell cortex of non-growing cell tip

The region directly beneath the plasma membrane at the cell tip at which no growth takes place.


dinoflagellate hypocone

The part of a dinoflagellate cell below the cingulum; also referred to as the posterior portion of a dinoflagellate cell. It is separated from the epicone by the cingulum.


nuclear outer membrane

The outer, i.e. cytoplasm-facing, lipid bilayer of the nuclear envelope; continuous with the endoplasmic reticulum of the cell and sometimes studded with ribosomes.


nuclear membrane

Either of the lipid bilayers that surround the nucleus and form the nuclear envelope; excludes the intermembrane space.


nuclear inner membrane

The inner, i.e. lumen-facing, lipid bilayer of the nuclear envelope.


germ tube

The slender tubular outgrowth first produced by most spores in germination.


virus tail, sheath

The external contractile envelope of the tail of some viruses. Its contraction ensures ejection of the virus DNA into the host cytoplasm.


lateral wall of outer hair cell

The lateral wall of an outer hair cell (OHC) is a unique trilaminate composite consisting of the plasma membrane, an underlying cytoskeletal network containing an actin-spectrin cortical lattice, and an adjacent system of circumferential lamellar organelles known as the subsurface cisternae.


pathogen-containing vacuole

A membrane-bound intracellular compartment that is formed upon internalization of a pathogen into a host cell, and in which the pathogen resides.


glial cell projection

A prolongation or process extending from a glial cell.


astrocyte end-foot

Terminal process of astrocyte abutting non-neuronal surfaces in the brain.


spiny bracelet of Nageotte

Paranodal terminations of Schwann cells that do not directly contact the paranodal axon membrane. Usually found in thicker myelin.


astrocyte projection

A prolongation or process extending from the soma of an astrocyte and wrapping around neurons.


glial limiting end-foot

Terminal process of astrocyte that extends to the surface of the central nervous system. Together, glial limiting end-feet form the glial limiting membrane or glia limitans.


terminal loop

Portion of myelin-forming Schwann cell consisting of terminal cytoplasmic extensions adhered to the axon at the beginning and end of the myelin sheath.


capitate projection

Simple or compound process of epithelial glial cells with a spherical head that inserts into photoreceptor axons. Capitate projections have only been observed in Brachycera (flies).


cerebellar granule cell to Purkinje cell synapse

A synapse of a granule cell fiber onto the dendrites of a Purkinje cell in cerebellum.


dense nuclear body

A location in the host cell nucleus where viral proteins colocalize late in infection prior to the onset of viral DNA synthesis. More than one site can be present simultaneously.


ventral disc microtubule array

A part of the ventral disc of Giardia species (trophozoite stage) consisting of a spiral array of microtubules linked to the ventral membrane. These microtubules form the base of the ventral disc dorsal microribbons that extend nearly perpendicular from the membrane.


chloroplast intermembrane space

The region between the inner and outer lipid bilayers of a chloroplast envelope.


Flemming body

A cell part that is the central region of the midbody characterized by a gap in alpha-tubulin staining. It is a dense structure of antiparallel microtubules from the central spindle in the middle of the intercellular bridge.


unencapsulated part of cell

The part of a cell encompassing the intracellular environment and the plasma membrane; it excludes any external encapsulating structures.


peroxisomal matrix

The volume contained within the membranes of a peroxisome; in many cells the matrix contains a crystalloid core largely composed of urate oxidase.


glyoxysomal lumen

The volume enclosed by the membranes of a glyoxysome.


glycosome lumen

The volume enclosed by the membrane of a glycosome.


lateral part of cell

The region of a polarized cell other than its tips or ends (in some cell types, one end may be called the apex and the other the base). For example, in a polarized epithelial cell, the lateral part includes the cell sides which interface adjacent cells.


lateral part of motile cell

The area of a motile cell perpendicular to the direction of movement.


ethanolamine degradation polyhedral organelle

An organelle found in bacteria consisting of a proteinaceous coat containing enzymes for the degradation of ethanolamine whose purpose is the protection of the rest of the cell from the toxic acetaldehyde product of the enzyme ethanolamine ammonia lyase.


Ubisch body

A small, granular structure that is found in the extracellular matrix of cell of the secretory tapetal layer that surrounds developing pollen grains. Ubisch bodies have a sporopollenin coat, are attached to the peritapetal wall, and may play a role in pollen development.


cytoplasmic microtubule plus-end

Any microtubule plus-end that is part of a cytoplasmic microtubule.


cortical microtubule plus-end

The plus-end of a cortical microtubule.


neutrophil extracellular trap

Extracellular microbicidal structure composed of nuclear chromatin, histones and granular antimicrobial proteins. Histones and several neutrophil granule proteins associated with the DNA framework damage entrapped microorganisms.


host cell chloroplast

A chlorophyll-containing plastid as found within host cells with thylakoids organized into grana and frets, or stroma thylakoids, and embedded in a stroma. The host is defined as the larger of the organisms involved in a symbiotic interaction.


host cell chloroplast thylakoid membrane

Any sac-like membranous structures (cisternae) in a chloroplast found in host cells, combined into stacks (grana) and present singly in the stroma (stroma thylakoids or frets) as interconnections between grana. The host is defined as the larger of the organisms involved in a symbiotic interaction.


host cell chloroplast part

Any constituent part of a chloroplast as it is found in host cells and which are a chlorophyll-containing plastid with thylakoids organized into grana and frets, or stroma thylakoids, and embedded in a stroma. The host is defined as the larger of the organisms involved in a symbiotic interaction.


neuromuscular junction

The junction between the axon of a motor neuron and a muscle fiber. In response to the arrival of action potentials, the presynaptic button releases molecules of neurotransmitters into the synaptic cleft. These diffuse across the cleft and transmit the signal to the postsynaptic membrane of the muscle fiber, leading to a change in post-synaptic potential.


excitatory neuromuscular junction of somatic myotube

A neuromuscular junction that functions in the excitation of somatic muscle myotubes, such as an arthropod somatic muscle cells.


inhibitory neuromuscular junction

The junction between the axon of a motor neuron and a muscle fiber. In response to the arrival of action potentials, the presynaptic button releases molecules of neurotransmitters into the synaptic cleft. These diffuse across the cleft and transmit the signal to the postsynaptic membrane of the muscle fiber, leading to a change in post-synaptic potential that inhibits muscle contraction.


inhibitory neuromuscular junction of somatic myotube

A neuromuscular junction that functions in the inhibition of somatic muscle myotube contraction. Examples of somatic muscle myotubes include the somatic muscle cells of arthropods.


neuromuscular junction of myotube

A neuromuscular junction in which the target muscle cell is a myotube.


neuromuscular junction of somatic muscle

A neuromuscular junction in which the target muscle cell is a somatic muscle cell, such as those found in nematodes and arthropods.


neuromuscular junction of somatic muscle myotube

A neuromuscular junction in which the target muscle cell is a somatic muscle myotube, such as an arthropod somatic muscle cell.


excitatory neuromuscular junction

The junction between the axon of a motor neuron and a muscle fiber. In response to the arrival of action potentials, the presynaptic button releases molecules of neurotransmitters into the synaptic cleft. These diffuse across the cleft and transmit the signal to the postsynaptic membrane of the muscle fiber, leading to a post-synaptic potential responsible for muscle contraction.


smooth endoplasmic reticulum membrane

The lipid bilayer surrounding the smooth endoplasmic reticulum.


excitatory synapse

A synapse in which an action potential in the presynaptic cell increases the probability of an action potential occurring in the postsynaptic cell.


parallel fiber to Purkinje cell synapse

An excitatory synapse formed by the parallel fibers of granule cells synapsing onto the dendrites of Purkinje cells.


cerebellar climbing fiber to Purkinje cell synapse

A synapse of a climbing fiber onto the dendrites of a Purkinje cell in cerebellum. The climbing fiber originates from the inferior olivary nucleus of the medulla oblongata.


asymmetric, glutamatergic, excitatory synapse

A neuron to neuron synapse with a postsynaptic density, that uses glutamate as a neurotransmitter and whose activity results in excitatory postsynaptic potentials.


P1 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. P1 peroxisomes are distinguished from the other subforms on the bases of buoyant density and protein content; they contain fewer peroxisomal proteins than the other subforms.


rhoptry membrane

The lipid bilayer surrounding a rhoptry.


lytic vacuole membrane

The lipid bilayer surrounding a lytic vacuole and separating its contents from the cytoplasm of the cell.


lysosomal membrane

The lipid bilayer surrounding the lysosome and separating its contents from the cell cytoplasm.


cytolytic granule membrane

The lipid bilayer surrounding the cytolytic granule.


fungal-type vacuole membrane

The lipid bilayer surrounding a vacuole, the shape of which correlates with cell cycle phase. The membrane separates its contents from the cytoplasm of the cell. An example of this structure is found in Saccharomyces cerevisiae.


autolysosome membrane

A lipid bilayer that surrounds an autolysosome, a single-membrane-bounded vesicle in which endogenous cellular material is degraded.


bacterial-type flagellum basal body, distal rod

The portion of the central rod of the bacterial-type flagellar basal body that is distal to the cell membrane; spans most of the distance between the inner and outer membranes.


outer endospore membrane

The outer membrane around a bacterial endospore, located between the endospore cortex and endospore coat.


chloroplast outer membrane

The outer, i.e. cytoplasm-facing, lipid bilayer of the chloroplast envelope.


cell outer membrane

A lipid bilayer that forms the outermost membrane of the cell envelope; enriched in polysaccharide and protein; the outer leaflet of the membrane contains specific lipopolysaccharide structures.


mycolate outer membrane

A mycolic acid-rich cell outer membrane containing a lipid bilayer and long-chain mycolic acids (hydroxylated branched-chain fatty acids) that are covalently linked to the cell wall peptidoglycan via an arabinogalactan network. Found in mycobacteria and related genera (e.g. corynebacteria).


organelle outer membrane

The outer, i.e. cytoplasm-facing in a cellular organelle, lipid bilayer of an organelle envelope.


plastid outer membrane

The outer, i.e. cytoplasm-facing, lipid bilayer of the plastid envelope.


nucleolus

A small, dense body one or more of which are present in the nucleus of eukaryotic cells. It is rich in RNA and protein, is not bounded by a limiting membrane, and is not seen during mitosis. Its prime function is the transcription of the nucleolar DNA into 45S ribosomal-precursor RNA, the processing of this RNA into 5.8S, 18S, and 28S components of ribosomal RNA, and the association of these components with 5S RNA and proteins synthesized outside the nucleolus. This association results in the formation of ribonucleoprotein precursors; these pass into the cytoplasm and mature into the 40S and 60S subunits of the ribosome.


lysosomal matrix

A matrix composed of supramolecular assemblies of lysosomal enzymes and lipids which forms at a pH of 5.0 within the lysosome.


intermediate layer of mitotic spindle pole body

Structure between the central and outer plaques of the mitotic spindle pole body.


lateral element

A proteinaceous core found between sister chromatids during meiotic prophase.


mitochondrial cloud

A prominent mass in the cytoplasm of previtellogenic oocytes. The cloud contains both mitochondria and electron-dense granulofibrillar material (GFM) and is the source of germinal granule material.


Bunina body

Small granular inclusions (about 1-3 microns in diameter) found in the anterior horn cells, and appearing either singly or in a group. Sometimes they are arranged in small beaded chains. Bunina bodies express cystatin C and consist of electron-dense amorphous material that contains tubules or vesicular structures. The amorphous material frequently includes a cytoplasmic island containing neurofilaments and other micro-organelles.


other organism part

Any constituent part of a secondary organism with which the first organism is interacting.


other organism cell membrane

The cell membrane of a secondary organism with which the first organism is interacting.


symbiont cell surface

The cell surface of a secondary, endosymbiont organism with which the first organism is interacting. The symbiont is defined as the smaller of the organisms involved in a symbiotic interaction.


trichocyst

A crystalline exocytotic organelle composed of small, acidic proteins existing primarily as disulphide-linked dimers. The trichocyst is an organelle that releases long filamentous proteins that capture predators in net-like structures, to slow them down when the cell is disturbed. The protein is nontoxic and shaped like a long, striated, fibrous shaft.


postsynaptic cytosol

The region of the cytosol consisting of all cytosol that is part of the postsynapse.


cytosolic region

Any (proper) part of the cytosol of a single cell of sufficient size to still be considered cytosol.


presynaptic cytosol

The region of the cytosol consisting of all cytosol that is part of the presynapse.


unicellular trichome tip

A cell projection part that is the apical most portion of a unicellular trichome apex.


2-micrometer circle DNA

A plasmid commonly found in Saccharomyces, inherited in a non-Mendelian manner and often present in 100-400 copies.


Lewy body corona

The periphery of a Lewy body. In Parkinson's disease, it contains spherical accumulations of filaments arranged in a loose, radiating array.


cleavage furrow rim

The part of the cleavage furrow closest to the cell surface.


right caudal basal body

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


Golgi cis cisterna

The Golgi cisterna closest to the endoplasmic reticulum; the first processing compartment through which proteins pass after export from the ER.


transmembrane actin-associated (TAN) line

A linear array of nuclear envelope membrane proteins composed of nesprin-2G and SUN2, which couple the nucleus to moving actin cables, resulting in rearward nuclear transport (away from the leading edge).


growth cone leading edge

That part of the growth cone which represents the distal part of the structure.


leading edge of axonal growth cone

That part of the axonal growth cone which represents the distal part of the structure.


gerontoplast

A plastid found in senescing, formerly green tissues that is derived from a chloroplast that undergoes an organized developmental program of senescence.


cholinergic synapse

A synapse that uses acetylcholine as a neurotransmitter.


protein storage vacuole membrane

The lipid bilayer surrounding a protein storage vacuole.


polyhydroxyalkanoate granule

An inclusion body located in the cytoplasm of prokaryotes that consists of polyhydroxyalkanoate (PHA) molecules and associated proteins, surrounded by a phospholipid monolayer; the proteins include PHA synthase, PHA depolymerase and 3HB-oligomer hydroxylase, phasins (PhaPs), which are thought to be the major structural proteins of the membrane surrounding the inclusion, and the regulator of phasin expression PhaR.


megasome

Large, cysteine proteinase rich lysosomes, often found in the amastigote (an intracytoplasmic, nonflagellated form of the parasite) stage of Leishmania species belonging to the mexicana complex.


cyanelle inner membrane

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


A multilamellar subcellular structure formed in the cytoplasm of developing neuron, composed of Tmem240 and Emd proteins.


early endosome lumen

The volume enclosed by the membrane of an early endosome.


late recombination nodule

An electron dense structure that is associated with meiotic chromosomes in pachytene during meiosis I.


bacterial-type flagellum basal body, rod

The central portion of the bacterial-type flagellar basal body, which spans the periplasm and threads through the rings.


contractile vacuole complex

A non-membrane-bounded organelle of eukaryotic cells, especially Protozoa, that fills with water from the cytoplasm and then discharges this externally. One of its functions is osmoregulatory.


kinetoplast

A sub-structure within the large single mitochondrion of kinetoplastid parasites and which is closely associated with the flagellar pocket and basal body of the flagellum.


antipodal site

The pole of the kinetoplast associated with kinetoplast DNA replication. The antipodal sites flank the kinetoplast DNA disk and are positioned approximately 180 degrees apart. In Trypanosoma brucei and Crithidia fasciculata, minicircles are attached at antipodal sites and they contain enzymes that catalyse some of the later reactions in minicircle replication.


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.


peroxisomal membrane

The lipid bilayer surrounding a peroxisome.


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 plasma membrane

The component of a plasma 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.


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.


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.


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.


chloroplast thylakoid

Sac-like membranous structures (cisternae) in a chloroplast combined into stacks (grana) and present singly in the stroma (stroma thylakoids or frets) as interconnections between grana. An example of this component is found in Arabidopsis thaliana.


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.


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.


thylakoid

A membranous cellular structure 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 plasma membrane. In eukaryotes 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.


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.


centriole

A cellular organelle, found close to the nucleus in many eukaryotic cells, consisting of a small cylinder with microtubular walls, 300-500 nm long and 150-250 nm in diameter. It contains nine short, parallel, peripheral microtubular fibrils, each fibril consisting of one complete microtubule fused to two incomplete microtubules. Cells usually have two centrioles, lying at right angles to each other. At division, each pair of centrioles generates another pair and the twin pairs form the pole of the mitotic spindle.


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.


mitotic spindle

A spindle that forms as part of mitosis. Mitotic and meiotic spindles contain distinctive complements of proteins associated with microtubules.


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.


polytene chromosome

A type of chromosome in a polyploid cell, formed when multiple copies of homologous chromosomes are aligned side by side to give a giant chromosome in which distinct chromosome bands are readily visible.


condensed chromosome

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


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.


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.


autophagosome membrane

The lipid bilayer surrounding an autophagosome, a double-membrane-bounded vesicle in which endogenous cellular material is sequestered.


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.