This is a wildly exciting period in the study of ion channels. Since the sequencing of Na+ and K+ channels was accomplished (Noda et al., 1984, Tempel et al., 1987), many of the functional parts of the channels have been located within the sequence. These include the pore through which ions travel (P region: Guy and Conti, 1990; Hartmann et al., 1991; Yellen et al., 1991), the voltage sensor (S4, the positively charged fourth transmembrane segment: Stühmer et al., 1989; Larsson et al., 1996; Yang et al., 1996) and the inactivation gate of both K and Na channels (NH2 terminus of Shaker B: Hoshi et al., 1990; for the Na channel, the linker between domains III and IV: Stühmer et al., 1989; West et al., 1992).
Missing from the list of identified functional parts...
