Immunological characterization of Na+ and K+ mediated structural states of rat kidney Na+-k+-ATPase.
As different structural states of the Na+-K+-ATPase (EC 3.6.1.3) may lead to a changed reactivity to antibodies, the influence of different ligands on the reaction between highly purified membrane-bound Na+-K+-ATPase and specific antibodies was investigated. The antigen antibody reaction was registered by measuring the antibody inhibition of Na+-K+-ATPase activity. It was found that Na+ decreased and K+ increased the antibody inhibition of the Na+-K+-ATPase activity of the membrane-bound enzyme if both Mg++ and ATP were present during the antigen antibody reaction. These effects were not observed if ATP was replaced by ADP or by the ATP analog adenylyl (beta-gamma-methylene) diphosphonate. If a solubilized enzyme preparation with the same specific activity was used the effects of Na+ or K+ which were demonstrated in the membrane-bound enzyme could not be detected. The study suggests that the Na+-K+-ATPase structure is altered by Na+ and K+, provided Mg++ and specifically the nucleotide ATP are also present. These structural changes are likely to occur during Na+-K+-transport and do not seem to be necessarily linked to the Na+, K+ and Mg++ stimulated ATP splitting of the enzyme.
D000818:Animals; D000937:Antigen-Antibody Reactions; D002462:Cell Membrane / Q000201:enzymology; D007679:Kidney Medulla / Q000201:enzymology*; D007700:Kinetics; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D005719:gamma-Globulins
D005719:gamma-Globulins; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium