K+-independent active transport of Na+ by the (Na+ and K+)-stimulated adenosine triphosphatase.
The (Na+ and K+)-stimulated adenosine triphosphatase (Na+,K+)-ATPase) from canine kidney reconstituted into phospholipid vesicles showed an ATP-dependent, ouabain-inhibited uptake of 22Na+ in the absence of added K+. This transport occurred against a Na+ concentration gradient, was not affected by increasing the K+ concentration to 10 microM (four times the endogenous level), and could not be explained in terms of Na+in in equilibrium Na+out exchange. K+-independent transport occurred with a stoichiometry of 0.5 mol of Na+ per mol of ATP hydrolyzed as compared with 2.9 mol of Na+ per mol of ATP for K+-dependent transport.
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D004285:Dogs; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D008081:Liposomes; D010713:Phosphatidylcholines; D011188:Potassium / Q000494:pharmacology*; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D008081:Liposomes; D010713:Phosphatidylcholines; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium