Structural determinants and biophysical properties of HERG and KCNQ1 channel gating

The delayed rectifier K(+) currents, I(Kr) and I(Ks,) play a critical role in modulating the plateau phase of the cardiac action potential. HERG encodes the alpha-subunit of channels underlying I(Kr), while I(Ks) is composed of subunits encoded by KCNQ1 and KCNE1. Mutations in any of these genes cause the long QT syndrome, a disorder of myocellular repolarization that predisposes affected individuals to life-threatening arrhythmias. Elucidation of the molecular basis of these currents has led to significant advancements in our understanding of fundamental properties of channel function. This review summarizes the current state of knowledge regarding the structural determinants and biophysical properties of HERG and KCNQ1 channels.