A bar model for the pump and channel function of the reconstituted Na+,K+-ATPase.
Purified Na+,K+-ATPase is treated with trypsin. The altered enzyme is then reconstituted into liposomes and the change in active and passive Na+,K+-fluxes is recorded. Trypsin treatment transforms the slow passive Na+,K+-fluxes into leaks. The leak formation is correlated with the degree of proteolysis and the associated decrease in Na+,K+-ATPase activity. The active Na+,K+-transport capacity decreases in parallel with the passive transport. It is thus proposed that the Na+,K+-ATPase molecule primarily contains unspecific transmembrane tunnels that are rendered ion-selective by transverse bars of specific length (bar model).
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D055598:Chemical Phenomena; D002621:Chemistry; D007473:Ion Channels; D008954:Models, Biological; D011188:Potassium / Q000378:metabolism; D011817:Rabbits; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014357:Trypsin / Q000494:pharmacology
D007473:Ion Channels; D012964:Sodium; D014357:Trypsin; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium