Mediates the voltage-dependent sodium ion permeability of excitable membranes (PubMed:29726066). Assuming opened or closed conformations in response to the voltage difference across the membrane, the protein forms a sodium-selective channel through which Na(+) ions may pass in accordance with their electrochemical gradient. ; [Isoform 5]: In macrophages and melanoma cells, may participate in the control of podosome and invadopodia formation.
