Pore-forming subunit of Nav1.7, a voltage-gated sodium (Nav) channel that directly mediates the depolarizing phase of action potentials in excitable membranes (PubMed:38381792, PubMed:40768348). Navs, also called VGSCs (voltage-gated sodium channels) or VDSCs (voltage-dependent sodium channels), operate by switching between closed and open conformations depending on the voltage difference across the membrane. In the open conformation they allow Na(+) ions to selectively pass through the pore, along their electrochemical gradient (PubMed:38381792, PubMed:40768348). The influx of Na(+) ions provokes membrane depolarization, initiating the propagation of electrical signals throughout cells and tissues (PubMed:15385606, PubMed:16988069, PubMed:17145499, PubMed:17167479, PubMed:19369487, PubMed:24311784, PubMed:25240195, PubMed:26680203, PubMed:7720699). Nav1.7 plays a crucial role in controlling the excitability and action potential propagation from nociceptor neurons, thereby contributing to the sensory perception of pain (PubMed:17145499, PubMed:17167479, PubMed:19369487, PubMed:24311784). {ECO:0000269|PubMed:15178348, ECO:0000269|PubMed:15385606, ECO:0000269|PubMed:16988069, ECO:0000269|PubMed:17145499, ECO:0000269|PubMed:17167479, ECO:0000269|PubMed:19369487, ECO:0000269|PubMed:24311784, ECO:0000269|PubMed:25240195, ECO:0000269|PubMed:26680203, ECO:0000269|PubMed:38381792, ECO:0000269|PubMed:40768348, ECO:0000269|PubMed:7720699}. This is the function of ENSG00000169432 (SCN9A, sodium voltage-gated channel alpha subunit 9).