Novel insights into K+ selectivity from high-resolution structures of an open K+ channel pore

Sheng Ye, Yang Li, Youxing Jiang

Research output: Contribution to journalArticle

100 Scopus citations

Abstract

K+ channels are highly selective for K+ over Na +. Here we present several crystal structures of the MthK K + channel pore at up to 1.45-Åresolution. The MthK selectivity filter maintains a conductive conformation even in the absence of K+, allowing the channel to conduct Na+. The high-resolution structures, along with single-channel recordings, allow for an accurate analysis of how K+ competes with Na+ in a conductive selectivity filter. At high K+ concentrations, two K+ ions equivalently occupy the four sites in the selectivity filter, whereas at low K+/high Na+ concentrations, a single K+ ion remains bound in the selectivity filter, preferably at site 1 or site 3. This single K+ binding at low concentration effectively blocks the permeation of Na +, providing a structural basis for the anomalous mole-fraction effect, a key property of multi-ion pores.

Original languageEnglish (US)
Pages (from-to)1019-1023
Number of pages5
JournalNature Structural and Molecular Biology
Volume17
Issue number8
DOIs
StatePublished - Aug 1 2010

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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