Download MendeleyNovel insights into K(+) selectivity from high-resolution structures of an open K(+) channel pore.
Ye, S., Li, Y., Jiang, Y.(2010) Nat Struct Mol Biol 17: 1019-1023
- PubMed: 20676101
- DOI: https://doi.org/10.1038/nsmb.1865
- Primary Citation of Related Structures:
3LDC, 3LDD, 3LDE - PubMed 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-A resolution. 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.
Organizational Affiliation:
Life Sciences Institute, Zhejiang University, Zhejiang, China. sye@zju.edu.cn
