Structural model of a voltage-gated potassium channel based on spectroscopic data

It is estimated that membrane proteins comprise as much as 30% of most geno mes. Yet our knowledge of membrane-protein folding is still in its infancy. Consequently, there is a great need for developing approaches that can fur ther advance our understanding of how peptides and proteins interact with m embranes and thereby attain their folded structure. An approach that we hav e been exploring involves dissecting voltage-gated ion channels into simple peptide domains for the purpose of determining their structure in differen t media using physical techniques. We have synthesized peptides correspondi ng to the six membrane-spanning segments, as well as the pore domain, of th e Shaker channel and characterized their secondary structures. From these s tudies we have developed a model for the transmembrane structure of the Sha ker potassium channel that is constructed from alpha -helices. The hard str uctural data obtained from these studies lends support to the recent theore tical models of this channel protein that have been developed by others.