期刊
EMBO JOURNAL
卷 35, 期 8, 页码 820-830出版社
WILEY
DOI: 10.15252/embj.201593285
关键词
crystal structure; electrophysiology; ion permeability; sodium channel
资金
- UK Biotechnology and Biological Science Research Council (BBSRC) [BB/H01070X, BB/L006790, BB/L02625]
- Pfizer Neusentis
- National Institutes of Health [T32-HL007572]
- NIH Pathway to Independence Award from National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) [K99/R00]
- European Community's Seventh Framework Programme under BioStruct-X [283570]
- BBSRC [BB/L026252/1, BB/L006790/1, BB/J020702/1] Funding Source: UKRI
- Biotechnology and Biological Sciences Research Council [BB/L006790/1, BB/J020702/1, BB/L026252/1] Funding Source: researchfish
Voltage-gated sodium channels are essential for electrical signalling across cell membranes. They exhibit strong selectivities for sodium ions over other cations, enabling the finely tuned cascade of events associated with action potentials. This paper describes the ion permeability characteristics and the crystal structure of a prokaryotic sodium channel, showing for the first time the detailed locations of sodium ions in the selectivity filter of a sodium channel. Electrostatic calculations based on the structure are consistent with the relative cation permeability ratios (Na+approximate to Li+>> K+, Ca2+, Mg2+) measured for these channels. In an E178D selectivity filter mutant constructed to have altered ion selectivities, the sodium ion binding site nearest the extracellular side is missing. Unlike potassium ions in potassium channels, the sodium ions in these channels appear to be hydrated and are associated with side chains of the selectivity filter residues, rather than polypeptide backbones.
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