Acid sensing ion channel subunits
acid sensing ion channel subunits
Acid-Sensing Ion Channels (ASICs) are neuronal voltage-insensitive cationic channels activated by extracellular protons. ASIC proteins are a subfamily of the ENaC/Deg superfamily of ion channels. To date five proteins of the ASIC family have been identified that arise from four genes, ASIC1, ASIC2, ASIC3, and ASIC4. ASIC1a, 1b and 2a, 2b are splice variants. ASICs are trimeric and can be made up of different combinations of subunits. ASIC2b is non functional on its own but modulates channel activity when participating in heteromultimers. ASIC4 has no known function. All ASICs are expressed in the peripheral nervous system while ASIC1a, 2a, 2b and 4 are expressed in the central nervous system. ASICs are Na+ permeable with ASIC1a showing low Ca++ permeability.