Scn2b: Proteins and Enzymes

Voltage-gated sodium channels (NaV) are responsible for action potential initiation and propagation in excitable cells, including nerve, muscle, and neuroendocrine cell types. They are also expressed at low levels in non-excitable cells, where their physiological role is unclear. Structurally, Nav channels are composed of one pore-forming alpha-subunit, which may be associated with either one or more beta-subunits. alpha-subunits are composed for four homologous domains, each of which contains six transmembrane segments. The fourth transmembrane loop (S4) acts as the 'voltage sensor' and is activated by changes in membrane potential. S4 is also involved in channel gating.