The protein encoded by SCN4B is one of several sodium channel beta subunits. These subunits interact with voltage-gated alpha subunits to change sodium channel kinetics. The encoded transmembrane protein forms interchain disulfide bonds with SCN2A. Defects in this gene are a cause of long QT syndrome type 10 (LQT10). Three protein-coding and one non-coding transcript variant have been found for this gene.
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.