Nature 1998 Feb 05;3916667:605-8. doi: 10.1038/35416.

The conduction pore of a cardiac potassium channel.

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Ion channels form transmembrane water-filled pores that allow ions to cross membranes in a rapid and selective fashion. The amino acid residues that line these pores have been sought to reveal the mechanisms of ion conduction and selectivity. The pore (P) loop is a stretch of residues that influences single-channel-current amplitude, selectivity among ions and open-channel blockade and is conserved in potassium-channel subunits previously recognized to contribute to pore formation. To date, potassium-channel pores have been shown to form by symmetrical alignment of four P loops around a central conduction pathway. Here we show that the selectivity-determining pore region of the voltage-gated potassium channel of human heart through which the I(Ks) current passes includes the transmembrane segment of the non-P-loop protein minK. Two adjacent residues in this segment of minK are exposed in the pore on either side of a short barrier that restricts the movement of sodium, cadmium and zinc ions across the membrane. Thus, potassium-selective pores are not restricted to P loops or a strict P-loop geometry.

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Species referenced: Xenopus
Genes referenced: kcne1 mink1