Mechanism of potassium ion uptake by the Na+/K+-ATPase
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The Na+/ K+-ATPase restores sodium (Na+) and potassium (K+) electrochemical gradients dissipated by action potentials and ion-coupled transport processes. As ions are transported, they become transiently trapped between intracellular and extracellular gates. Once the external gate opens, three Na+ ions are released, followed by the binding and occlusion of two K+ ions. While the mechanisms of Na+ release have been well characterized by the study of transient Na+ currents, smaller and faster transient currents mediated by external K+ have been more difficult to study. Here we show that external K+ ions travelling to their binding sites sense only a small fraction of the electric field as they rapidly and simultaneously become occluded. Consistent with these results, molecular dynamics simulations of a pump model show a wide water-filled access channel connecting the binding site to the external solution. These results suggest a mechanism of K+ gating different from that of Na+ occlusion.
Artículo de publicación ISI
Fogarty International Research Collaboration Award RO3 TW008351 NIH R01-GM062342 R01-GM030376 U54-GM087519 FONDECYT 1110430 1150273 Millennium Scientific Initiative of the Chilean Ministry of Economy, Development and Tourism NIH (NINDS) National Institutes of Health P41GM103712-S1 Pittsburgh Supercomputing Center (PSC)
DOI: DOI: 10.1038/ncomms8622
Quote ItemNature Communications 6:7622 2015
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