Purification and characterization of the Ca2+-ATPase of plasma membranes from Ehrlich ascites mammary carcinoma cells.
Ca2+-ATPase was isolated from plasma membranes of Ehrlich ascites mammary carcinoma cells by means of calmodulin affinity chromatography. The purification procedure included removal of endogenous calmodulin from a Triton X-100 solubilizate of the membranes by DEAE ion-exchange chromatography as an essential step. With respect to its molecular mass, activation by calmodulin, Ca2+-dependent phosphorylation and highly sensitive inhibition by orthovanadate, the purified enzyme resembles the Ca2+-ATPase of erythrocyte membranes. In contrast to the strong calmodulin dependence of the isolated enzyme the Ca2+-ATPase in native Ehrlich ascites carcinoma cell membranes cannot be remarkably stimulated by added calmodulin. It is suggested that the membrane-bound Ca2+-ATPase in the presence of Ca2+ is activated by interaction with endogenously bound calmodulin.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism / Q000494:pharmacology; D002148:Calmodulin-Binding Proteins / Q000378:metabolism; D002286:Carcinoma, Ehrlich Tumor / Q000201:enzymology*; D002462:Cell Membrane / Q000201:enzymology; D002846:Chromatography, Affinity; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000201:enzymology; D007700:Kinetics; D010766:Phosphorylation; D014638:Vanadates; D014639:Vanadium / Q000494:pharmacology
D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D014639:Vanadium; D014638:Vanadates; D000252:Calcium-Transporting ATPases; D002118:Calcium