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Science 21 July 1995:
Vol. 269. no. 5222, pp. 410 - 412
DOI: 10.1126/science.7618108
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Articles

Science, Vol 269, Issue 5222, 410-412
Copyright © 1995 by American Association for the Advancement of Science

articles

Permeation selectivity by competition in a delayed rectifier potassium channel

SJ Korn and Ikeda SR

Department of Physiology and Neurobiology, University of Connecticut, Storrs 06269, USA.

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.


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