A transport model for the (Na+/K+)ATPase in liposomes including the (Na+/K+)-channel function.
(Na+/K+)ATPase liposomes of various degrees of reconstitution are formed by varying the amount of phosphatidylcholine added to the soluble (Na+/K+)ATPase before vesicles are formed by cholate removal. In the presence of ATP, the reconstituted sodium pump effectuates (Na+/K+) antiport. In the absence of ATP, the reconstituted sodium pump forms a (Na+/K+) channel. The stable plateaus formed by (1) the active Na+ transport, (2) the active K+ transport, (3) the 'passive' Na+ flux, and (4) the 'passive' K+ flux are determined in the optimally and the partially reconstituted liposomes. The activities of all four vectorial functions vary in a tightly correlated fashion, suggesting that they are mediated by the same transport-active configuration of (Na+/K+)ATPase. A transport model which includes the active and the passive (Na+/K+) fluxes mediated by the sodium pump in liposomes is outlined.
D000255:Adenosine Triphosphate / Q000378:metabolism; D001692:Biological Transport; D001693:Biological Transport, Active; D007473:Ion Channels; D008081:Liposomes / Q000378:metabolism*; D008954:Models, Biological; D011188:Potassium / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D007473:Ion Channels; D008081:Liposomes; D000255:Adenosine Triphosphate; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium