Explain why the (Na+-K+)-ATPase carries out transport in one direction only.

Explain why the (Na⁺-K⁺)-ATPase carries out transport in one direction only.

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Expert Solution

Na+/K+-ATPase restores sodium (Na+) and potassium (K+) electrochemical gradients dissipated by action potentials and ion-coupled transport processes. As the ions are transported, they become transiently trapped between intracellular and extracellular gates. Once 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. It was seen that thethat external K+ ions travelling to their binding sites sense only a small fraction of the electric field as they rapidly and simultaneously become occluded. Being 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.

gladiator answered 1 year ago

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