spacer Potassium Channel KcsA-Fab complex in high concentration of K+
Primary citation
Title Chemistry of ion coordination and hydration revealed by a K+ channel-Fab complex at 2.0 A resolution.
Authors Zhou,; Morais-Cabral,; Kaufman,; MacKinnon,
Journal NATUREsearch vol:414, pag:43-48 (2001), Identifiers: PubMed ID (11689936)search DOI (10.1038/35102009)
Abstract Ion transport proteins must remove an ion's hydration shell to coordinate the ion selectively on the basis of its size and charge. To discover how the K+ channel solves this fundamental aspect of ion conduction, we solved the structure of the KcsA K+ channel in complex with a monoclonal Fab antibody fragment at 2.0 A resolution. Here we show how the K+ channel displaces water molecules around an ion at its extracellular entryway, and how it holds a K+ ion in a square antiprism of water molecules in a cavity near its intracellular entryway. Carbonyl oxygen atoms within the selectivity filter form a very similar square antiprism around each K+ binding site, as if to mimic the waters of hydration. The selectivity filter changes its ion coordination structure in low K+ solutions. This structural change is crucial to the operation of the selectivity filter in the cellular context, where the K+ ion concentration near the selectivity filter varies in response to channel gating.
MeSH terms Animalssearch, Antibodiessearch, Monoclonalsearch, Bacterial Proteinssearch, Crystallographysearch, X-Raysearch, Electrochemistrysearch, Immunoglobulin Fab Fragmentssearch, Micesearch, Modelssearch, Biologicalsearch, Modelssearch, Molecularsearch, Particle Sizesearch, Potassiumsearch, Potassium Channelssearch, Protein Conformationsearch, Solutionssearch, Watersearch
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