Sodium channel protein type 4 subunit alpha (NaV1.4) (NaV1.4)

Sodium channel protein type 4 subunit alpha (NaV1.4) is a critical voltage-gated ion channel primarily expressed in the sarcolemma of skeletal muscle fibers (UniProt P35499). It is responsible for the rapid upstroke of the action potential, which is the essential electrical signal that triggers excitation-contraction coupling and subsequent muscle movement (PubMed: 26300336). Mutations in the SCN4A gene encoding this protein lead to a group of disorders known as skeletal muscle channelopathies, including various forms of myotonia and periodic paralysis (StatPearls: NBK540981). In drug discovery, NaV1.4 is a target for anti-myotonic agents like mexiletine, which reduce muscle hyperexcitability by blocking the channel in a frequency-dependent manner (NCBI: PMC6110313). A major challenge in developing therapeutics for NaV1.4 is achieving isoform selectivity to avoid life-threatening off-target effects on cardiac (NaV1.5) and neuronal sodium channels (PubMed: 29445114).

Other names

SCN4ASkM1Sodium channel protein skeletal muscle subunit alphaVoltage-gated sodium channel subunit alpha Nav1.4Type IV voltage-gated sodium channel alpha subunit

Drugs typically act as pore blockers or state-dependent inhibitors that stabilize the inactivated state of the channel, thereby reducing the influx of sodium ions and decreasing membrane excitability.