Ion permeation in K⁺ channels occurs by direct Coulomb knock-on

David A. Köpfer, Chen Song (Lead / Corresponding author), Tim Gruene, George M. Sheldrick, Ulrich Zachariae (Lead / Corresponding author), Bert L. de Groot (Lead / Corresponding author)

Research output: Contribution to journalArticlepeer-review

146 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)352-355
Number of pages4
JournalScience
Volume346
Issue number6207
DOIs
Publication statusPublished - 17 Oct 2014

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