Interaction of the purified Ca2+, Mg2+-ATPase from human erythrocytes with phospholipids and calmodulin.
The Ca2+-pumping ATPase has been purified in a functional form from human erythrocytes by calmodulin affinity chromatography. The purified enzyme has a specific activity at least 300-fold higher than the membrane bound enzyme. It consists of one major protein band of 140000 Dalton, and after reconstitution in liposomes it transports Ca2+ with an efficiency of at least 1 Ca2+/ATP. In the presence of calmodulin, the affinity of the enzyme for Ca2+, and its specific activity, are greatly increased. Acidic phospholipids have an unexpected effect on the isolated enzyme: ATPase isolated or reconstituted in acidic phospholipids behaves as if calmodulin were present. Acidic phospholipids mimic the effect of calmodulin.
D017301:Ca(2+) Mg(2+)-ATPase; D002118:Calcium / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000494:pharmacology*; D000252:Calcium-Transporting ATPases / Q000097:blood* / Q000302:isolation & purification; D002147:Calmodulin / Q000494:pharmacology*; D004910:Erythrocyte Membrane / Q000201:enzymology*; D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D007700:Kinetics; D010743:Phospholipids / Q000494:pharmacology*; D012519:Sarcoplasmic Reticulum / Q000201:enzymology
D002135:Calcium-Binding Proteins; D002147:Calmodulin; D010743:Phospholipids; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D002118:Calcium