Ion permeation in K + channels occurs by direct Coulomb knock-on
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- 17 October 2014
- journal article
- other
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 346 (6207), 352-355
- https://doi.org/10.1126/science.1254840
Abstract
Potassium channels selectively conduct K + ions across cellular membranes with extraordinary efficiency. Their selectivity filter exhibits four binding sites with approximately equal electron density in crystal structures with high K + concentrations, previously thought to reflect a superposition of alternating ion- and water-occupied states. Consequently, cotranslocation of ions with water has become a widely accepted ion conduction mechanism for potassium channels. By analyzing more than 1300 permeation events from molecular dynamics simulations at physiological voltages, we observed instead that permeation occurs via ion-ion contacts between neighboring K + ions. Coulomb repulsion between adjacent ions is found to be the key to high-efficiency K + conduction. Crystallographic data are consistent with directly neighboring K + ions in the selectivity filter, and our model offers an intuitive explanation for the high throughput rates of K + channels.Keywords
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