Kinetic studies and characteristics of a modifier of Ca2+-stimulated ATPase.
1. The thermostable modifier increases the Mg2+-stimulated ATPase with a parallel decrease of Ca2+-stimulated ATPase. 2. The modifier inhibited Ca2+-stimulated ATPase by diminishing the velocity without any significant effect on the apparent affinity of binding of Ca2+. 3. The inhibition of Ca2+-stimulated ATPase was independent of Ca2+ concentration and could not be reversed by increasing Ca2+ levels. 4. Monovalent cations and calmodulin increased the Mg2+-stimulated ATPase in the presence of the modifier.
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors*; D002147:Calmodulin / Q000494:pharmacology; D002414:Cations, Monovalent / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000201:enzymology; D006358:Hot Temperature; D066298:In Vitro Techniques; D007700:Kinetics; D051381:Rats
D002147:Calmodulin; D002414:Cations, Monovalent; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases