Co-operative gating interactions in the yeast TOK1 K+ channel

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K+ channels play major roles in all living cells, providing a pore, or pathway for K+ ion movements across membranes. How these channels are constructed and the mechanisms by which they regulate (gate) the flow of K+ through their pores is a field of intense research. We know now that the pores of all K+ channels comprise four protein domains, each with a pore loop and two, flanking transmembrane helices. Gating of these channels has generally been thought to arise from independent protein conformational changes within each domain that contribute to opening the pore. The yeast K+ channel TOK1 is gated both by voltage and by extracellular K+. Surprisingly, we recently uncovered evidence of long-distance interactions between putative K+-binding sites associated with each pore loop. The results identify an unanticipated co-operativity between adjacent pore domains and, thus, should provide new insights into the gating of these channels. An extension to the current project will enable us to systematically explore these interactions and their implications for the molecular functioning of the TOK1 K+ channel.