Cation channel with high affinity for sodium, which is gated by extracellular protons and inhibited by the diuretic amiloride. Also permeable for Li(+) and K(+). Generates a biphasic current with a fast inactivating and a slow sustained phase. Heteromeric channel assembly seems to modulate. Homotrimer or heterotrimer with other ASIC proteins (By similarity). Interacts with PRKCABP and ASIC3 (By similarity). Interacts with STOM; this regulates channel activity (PubMed:15471860, PubMed:22850675). Heterotrimer of Asic1a-Asic2a interacts with the snake venom mambalgin-1, mambalgin-2 and mambalgin-3 (By similarity). Heterotrimer of Asic1a-Asic2b interacts with the snake venom mambalgin-1 and mambalgin-2 (By similarity). Localized at the plasma membrane, in the soma and punctated peripheral processes of neurons. Expressed by sensory neurons. Expressed by nociceptive sensory neurons, spiral ganglion (SG) neurons and the retina (at protein level). Isoform 1 and isoform 2 are expressed in outer nuclear layer of retina (photoreceptors) and to a lower extent in distal and proximal inner nuclear layer. Expression changes dramatically during cochlear development. Expression is detected at 11.5 dpc in otocyst and increases in the SG neurons after 18.5 dpc. Also detected in the lumen side of all cells forming the vestibular cavity and at the top of the macula of saccule and utricle. Before birth expressed by epithelial cells facing the endolymphatic space. Post-natally expressed by cells in the apical turn of the cochlea, while expression on the lumen side of the membranous labyrinth decreases. Expression shifts gradually toward the top of supporting cells and the spiral limbus. Also expressed by vestibular ganglion neurons. Restricted to the SG neurons in the mature cochlea (at protein level). Expression in a subset of neurons may be regulated by neurotrophins. Mice display altered rod phototransduction and neurotransmission, associated with increased light-induced retina damages. Regulated by Zn(2+). Inhibited by anti-inflammatory drugs like salicylic acid (By similarity). Belongs to the amiloride-sensitive sodium channel (TC 1.A.6) family. ASIC2 subfamily.