Voltage-gated ion channels have always been overachievers. They have the singular distinction of having solved the permeation problem five times over. Not only do they have a central, highly selective pore through which they conduct charged ions, they also have four peripheral “pores” or gating canals through which they conduct the charged portions of their voltage sensors. This trick of protein permeation generates a small gating current as the S4 arginines and lysines move through the electric field of the membrane and ultimately results in channel opening.
The membrane-spanning portion of voltage-gated channels contains two classes of functional domains. Four voltage-sensing domains located at the periphery of the tetramer surround a central pore forming domain (Fig. 1 B). The pore domain of the voltage-gated K+ (Kv) channels share structural homology with the bacterial KcsA and MthK channels whose crystal structures have been solved...
