期刊
SCIENCE
卷 346, 期 6207, 页码 352-355出版社
AMER ASSOC ADVANCEMENT SCIENCE
DOI: 10.1126/science.1254840
关键词
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资金
- International Max Planck Research School for Biology and Complex Systems
- Marie Curie Intra European Fellowship within European Community
- Volkswagen Stiftung
- Scottish Universities' Physics Alliance
- German research foundation DFG [SFB803]
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.
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