The acid-sensing ion channel (ASIC) has a prominent role in tissue pH-sensing and neuronal signalling.Subunits of ASICs are members of the degenerin/epithelial Na+ channel protein superfamily.To date, seven ASIC subunits have been identified: ASICla, ASIClb, ASIClb2, ASIC2a, ASIC2b, ASIC3, and ASIC4.Each subunit contains cytosolic N and C termini, two alpha-helical transmembrane domains (M1-M2), and a disulfide-rich multidomain extracellular region.They form a variety of homo-and heterotrimeric ion channels that are activated by extracellular acidosis associated with neurotransmission, injury, inflammation and ischemia, triggering membrane depolarization via Na+ influx into target neurons.