Fluorescence-Tracking of Activation Gating in Human ERG Channels Reveals Rapid S4 Movement and Slow Pore Opening

Abstract

THE DATA INDICATE: 1) that rapid environmental changes occur at the outer end of S4 in hERG channels that underlie channel activation gating, and 2) that secondary slower changes reflect channel pore opening during sustained depolarizations, and channel closing upon repolarization. 3) No direct evidence was obtained of conformational changes related to inactivation from fluorophores attached at the outer end of S4.