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Updated: Aug 25, 2026

Mutagenesis and Functional Analysis of Ion Channels Heterologously Expressed in Mammalian Cells
Published on: October 1, 2010
Functional influence of the pore helix glutamate in the KcsA K+ channel
HoSook Choi1, Lise Heginbotham
1Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA.
Abstract:
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.
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