Forms pH-gated trimeric sodium channels that act as postsynaptic excitatory sensors in the nervous system (PubMed:10842183, PubMed:23034652, PubMed:8626462, PubMed:8631835). Upon extracellular acidification, these channels generate rapid, transient inward currents that fully desensitize (PubMed:10842183). Highly selective for sodium, they are permeable to other cations (PubMed:8626462, PubMed:8631835). By forming heterotrimeric channels with ASIC1, could contribute to synaptic plasticity, learning, and memory. Additionally, as acid sensors at nerve terminals, plays a role in mechanosensation and phototransduction (By similarity). {ECO:0000250|UniProtKB:Q925H0, ECO:0000269|PubMed:10842183, ECO:0000269|PubMed:23034652, ECO:0000269|PubMed:8626462, ECO:0000269|PubMed:8631835}. This is the function of ENSG00000108684 (ASIC2, acid sensing ion channel subunit 2).