Ca(2+)-induced alterations in the activity of membrane (Ca(2+)-Mg2+)-ATPase of human and rat erythrocytes.
Effect of intraerythrocyte Ca2+ elevation on human and rat erythrocyte membrane (Ca(2+)-Mg2+)-ATPase along with that of incubation of the erythrocyte ghosts in their own hemolysates enriched with Ca2+ has been studied. While the membrane (Ca(2+)-Mg2+)-ATPase levels of Ca(2+)-loaded human erythrocytes showed an initial increase and subsequent decline, membranes incubated in their own hemolysate showed a consistent decrease in the enzyme activity. Calmodulin sensitivity was retained by the preparations in contrast to the earlier observations made with washed erythrocyte membranes. Similar changes in (Ca(2+)-Mg2+)-ATPase activity but of greater magnitude were observed in response to Ca2+ in the calpain-rich rat erythrocytes. Considerable crosslinking and proteolysis was observed in case of human and rat erythrocytes exposed to high Ca2+ concentrations. The Ca(2+)-activable transglutaminase, however, did not play any role in the activation of the (Ca(2+)-Mg2+)-ATPase.
Zaidi
A
A
Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, India.
Saleemuddin
M
M
D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000097:blood*; D002118:Calcium / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000201:enzymology; D006801:Humans; D066298:In Vitro Techniques; D008563:Membrane Lipids / Q000097:blood; D051381:Rats
D008563:Membrane Lipids; D017301:Ca(2+) Mg(2+)-ATPase; D002118:Calcium