Functional influence of the pore helix glutamate in the KcsA K+ channel

被引:22
作者
Choi, H [1 ]
Heginbotham, L [1 ]
机构
[1] Yale Univ, Dept Mol Biophys & Biochem, New Haven, CT 06520 USA
关键词
D O I
10.1016/S0006-3495(04)74273-3
中图分类号
Q6 [生物物理学];
学科分类号
071011 ;
摘要
The E71 residue is buried near the selectivity filter in the KcsA K+ channel and forms a carboxyl-carboxylate bridge with D80. We have investigated the importance of E71 by examining neutralization mutants at this position using biochemical and electrophysiological methods. E71 mutations differentially destabilize the detergent-solubilized tetramer; among them, the E71V neutralization mutant has a relatively subtle effect. The E71V channel displays electrical activity when reconstituted into planar lipid bilayers. In single channel recordings, the mutant retains K+/Na+ selectivity, and its conductance in the outward direction is unaltered. Some conduction properties are changed: inward conductance is increased. Our results show that that the E71 side chain is not a primary determinant of ion selectivity or conduction in the wild-type channel, either directly or through the E71:D80 carboxyl-carboxylate bridge.
引用
收藏
页码:2137 / 2144
页数:8
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