Fig. 5.

Schematics of the “ball-and-chain” model of channel inactivation. (A) Closed state. (B) Open state. (C) Inactivated state. According to this model, the N terminus represents a tethered plug that can physically block the intracellular side of the ion channel pore and cause inactivation. Different lengths of the N terminus region result in different rates of channel inactivation (45, 46), where a shorter N terminus (D) causes a more rapid inactivation in comparison to a longer N terminus (E).