title: ATPase and phosphatase activities from human red cell membranes: II. The effects of phospholipases on Ca2+-dependent enzymic activities.
abstract: Treatment of human red cell membranes with pure phospholipase A2 results in a progressive inactivation of both Ca2+-dependent and (Ca2+ + K+)-dependent ATPase and phosphatase activities. When phospholipase C replaces phospholipase A2, Ca2+-dependent ATPase activity and Ca2+-dependent phosphorylation of red cell membranes are lost, while Ca2+-dependent phosphatase activity is enhanced and its apparent affinity for Ca2+ is increased about 20-fold. Activation of Ca2+-dependent phosphatase following phospholipase C treatment was not observed in sarcoplasmic reticulum preparation. Phospholipase C increases the sensitivity of the phosphatase to N-ethylmaleimide but has little effect on the kinetic parameters relating the phosphatase activity to substrate and cofactors, suggesting that no extensive structural disarrangement of the Ca2+-ATPase system has occurred after incubation with phospholipase C.
mesh_terms: D000251:Adenosine Triphosphatases / Q000097:blood*; D000255:Adenosine Triphosphate / Q000097:blood; D000818:Animals; D002118:Calcium / Q000097:blood*; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D004912:Erythrocytes / Q000201:enzymology*; D005033:Ethylmaleimide / Q000494:pharmacology; D006801:Humans; D006868:Hydrolysis; D008563:Membrane Lipids / Q000097:blood; D009943:Organophosphorus Compounds / Q000097:blood; D010740:Phospholipases / Q000494:pharmacology*; D010750:Phosphoproteins / Q000097:blood; D010744:Phosphoric Monoester Hydrolases / Q000097:blood*; D051381:Rats; D012519:Sarcoplasmic Reticulum / Q000201:enzymology
chemical_list: D008563:Membrane Lipids; D009943:Organophosphorus Compounds; D010750:Phosphoproteins; D000255:Adenosine Triphosphate; D010740:Phospholipases; D010744:Phosphoric Monoester Hydrolases; D000251:Adenosine Triphosphatases; D005033:Ethylmaleimide; D002118:Calcium