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Potassium channel from Magnetospirillum magnetotacticum
Structural highlights
FunctionIRK10_MAGMG Inward rectifier potassium channel that mediates potassium uptake into the cell. Inward rectifier potassium channels are characterized by a greater tendency to allow potassium to flow into the cell rather than out of it. The inward rectification may be achieved by the blockage of outward current by cytoplasmic divalent metal ions and polyamines. Complements an E.coli mutant that is defective in K(+) uptake.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedPotassium channels embedded in cell membranes employ gates to regulate K+ current. While a specific constriction in the permeation pathway has historically been implicated in gating, recent reports suggest that the signature ion selectivity filter located in the outer membrane leaflet may be equally important. Inwardly rectifying K+ channels also control the directionality of flow, using intracellular polyamines to stem ion efflux by a valve-like action. This study presents crystallographic evidence of interdependent gates in the conduction pathway and reveals the mechanism of polyamine block. Reorientation of the intracellular domains, concomitant with activation, instigates polyamine release from intracellular binding sites to block the permeation pathway. Conformational adjustments of the slide helices, achieved by rotation of the cytoplasmic assembly relative to the pore, are directly correlated to the ion configuration in the selectivity filter. Ion redistribution occurs irrespective of the constriction, suggesting a more expansive role of the selectivity filter in gating than previously appreciated. Domain reorientation and rotation of an intracellular assembly regulate conduction in Kir potassium channels.,Clarke OB, Caputo AT, Hill AP, Vandenberg JI, Smith BJ, Gulbis JM Cell. 2010 Jun 11;141(6):1018-29. PMID:20564790[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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