Activation of erythrocyte membrane Ca2+-ATPase by calpain.
Ca2+-ATPase of erythrocyte membranes, prepared from erythrocytes substantially removed of contaminating leukocytes, was found to be activated by calpain isolated from the same source. Saponin or glycodeoxycholate treatment of membranes was essential for elicitation of the calpain response. Unlike the membrane bound ATPase, solubilized ATPase was inactivated by calpain. Digestion of membranes with the protease did not affect the Km (ATP) of Ca2+-ATPase though stimulation of the membrane ATPase by calmodulin could be partially substituted by calpain treatment. As compared with control, Ca2+-ATPase of calpain-digested membranes attained maximal activity at a lower free Ca2+ concentration.
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Department of Biochemistry, University of Hong Kong.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002154:Calpain / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000201:enzymology*; D006002:Glycodeoxycholic Acid / Q000494:pharmacology; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D012503:Saponins / Q000494:pharmacology; D012995:Solubility; D013552:Swine
D008565:Membrane Proteins; D012503:Saponins; D006002:Glycodeoxycholic Acid; D002154:Calpain; D000252:Calcium-Transporting ATPases; D002118:Calcium