Sodium channel protein type 4 subunit alpha (Nav1.4)

Sodium channel protein type 4 subunit alpha is the pore-forming alpha subunit of the Nav1.4 voltage-gated sodium channel. It is responsible for mediating the depolarizing phase of action potentials in excitable membranes such as skeletal muscle cells, controlling the flow of sodium ions (Na+) into muscle cells during electrical signaling required for muscle contraction and relaxation. Mutations in SCN4A have been linked to several neuromuscular disorders.

Other names

Na(V)1.4SkM1Mu1NAC1ANCHVSHSkM1RSkM1MH2MicroI[2][5][7]

Voltage-gated sodium channels like Nav1.4 open upon membrane depolarization allowing rapid influx of Na+, which triggers further depolarization necessary for action potential propagation along nerves and muscles. Mutations alter gating properties—either causing persistent inward currents (myotonia) or inability to repolarize (paralysis)