hNaV 1.5

The voltage-gated Nav1.5 channel is the pore-forming alpha subunit of a functional Na⁺ channel, the latter comprised of five channel forming and regulating subunits. The major component of Na⁺ channels in the heart, Nav1.5 is highly sensitive to tetrodotoxin (TTX), a lethal poison produced by puffer fish. The Nav1.5 current is responsible for the initial upstroke (depolarization) of the cardiac action potential. Mutations in the SCN5A gene encoding Nav1.5 have been implicated in long QT syndrome (LQT3) and ventricular fibrillation.