Sodium channel protein type 4 subunit alpha (SCN4A) (SCN4A)

Sodium channel protein type 4 subunit alpha (SCN4A), also known as Nav1.4, is a critical voltage-gated sodium channel primarily expressed in the sarcolemma of skeletal muscle [2, 5]. It is responsible for the rapid influx of sodium ions that initiates the depolarizing phase of the action potential, a process fundamental to muscle contraction [4, 6]. Mutations in the SCN4A gene lead to a spectrum of rare neuromuscular disorders known as skeletal muscle sodium channelopathies, which include paramyotonia congenita, hyperkalemic periodic paralysis, and sodium channel myotonia [1, 10]. These conditions are characterized by either muscle hyperexcitability (myotonia) or episodic weakness (paralysis), depending on whether the mutation causes a gain or loss of channel function [7, 13]. SCN4A is a validated therapeutic target; for instance, the sodium channel blocker mexiletine is used to treat myotonia by stabilizing the muscle membrane [3, 16]. Therapeutic challenges include the need for isoform specificity to avoid cardiac side effects related to the Nav1.5 channel and managing the complex triggers of periodic paralysis [14, 17].

Other names

Nav1.4SkM1HYPPHYKPPSodium channel protein skeletal muscle subunit alphaSodium channel protein type IV subunit alphaSodium voltage-gated channel alpha subunit 4

Sodium channel blockade, modulation of gating kinetics, and stabilization of the muscle membrane