Permeation selectivity by competition in a delayed rectifier potassium channel.
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.
Korn
S J
SJ
Department of Physiology and Neurobiology, University of Connecticut, Storrs 06269, USA.
Ikeda
S R
SR
D000818:Animals; D001667:Binding, Competitive; D051668:Delayed Rectifier Potassium Channels; D006801:Humans; D007739:L Cells; D008564:Membrane Potentials; D051379:Mice; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D051669:Shab Potassium Channels; D012964:Sodium / Q000378:metabolism*
D051668:Delayed Rectifier Potassium Channels; C496988:KCNB1 protein, human; C496990:Kcnb1 protein, mouse; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D051669:Shab Potassium Channels; D012964:Sodium; D011188:Potassium