Permeation selectivity by competition in a delayed rectifier potassium channel

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Science  21 Jul 1995:
Vol. 269, Issue 5222, pp. 410-412
DOI: 10.1126/science.7618108


Permeation selectivity was studied in two human potassium channels, Kv2.1 and Kv1.5, expressed in a mouse cell line. With normal concentrations of potassium and sodium, both channels were highly selective for potassium. On removal of potassium, Kv2.1 displayed a large sodium conductance that was inhibited by low concentrations of potassium. The channel showed a competition mechanism of selectivity similar to that of calcium channels. In contrast, Kv1.5 displayed a negligible sodium conductance on removal of potassium. The observation that structurally similar potassium channels show different abilities to conduct sodium provides a basis for understanding the structural determinants of potassium channel selectivity.