The SCN4B protein modulates channel gating kinetics. Causes negative shifts in the voltage dependence of activation of certain alpha sodium channels, but does not affect the voltage dependence of inactivation. The protein has been found to be expressed at a high level in dorsal root ganglia, at a lower level in brain, spinal cord, skeletal muscle and heart. Defects in SCN4B are the cause of long QT syndrome type 10 (LQT10) [MIM:611819]. Long QT syndromes are heart disorders characterized by a prolonged QT interval on the ECG and polymorphic ventricular arrhythmias. They cause syncope and sudden death in response to exercise or emotional stress. They can present with a sentinel event of sudden cardiac death in infancy.
Sodium channel subunit beta-4; sodium channel, voltage gated, type IV beta subunit; sodium channel, voltage-gated, type IV, beta subunit