[Molecular mechanisms underlying gating activity of voltage dependent ion channels]

A model of two-channel and its activation and inactivation proposed by Hodgkin and Huxley in 1950s have been continuously confirmed by molecular biological and electrophysiological studies since 1980s. The activation of Na+ and K+ channels seems to be dependent on screw-like rotation outward of S4 segment which is highly conservative and very rich in positively charged amino acid residues. The inactivation of Na+ channels appears to be related to "hinged lids" like movement of intracellular linker between domain III and IV; type N-, C-, and P- of inactivation can be divided in K+ channels, which seems to occur mainly in terminal N-, C- and region P, respectively and the N-type inactivation seems to be related to "ball and chain" like movement of terminal N.