ATPase and phosphatase activities from human red cell membranes. III. Stimulation of K+-activated phosphatase by phospholipase C.
Treatment of red cell membranes with pure phospholipase C inactivates (Na+ + K+)-ATPase activity and Na+-dependent phosphorylation but increases K+-dependent phosphatase activity. When phospholipase A2 replaces phospholipase C, all activities are lost. Activation of K+-dependent phosphatase by treatment with phospholipase C is caused by an increase in the maximum rate of hydrolysis of p-nitrophenylphosphate and in the maximum activating effect of K+, the apparent affinities for substrate and cofactors being little affected. After phospholipase C treatment K+-dependent phosphatase is no longer sensitive to ouabain but becomes more sensitive to N-ethylmaleimide. In treated membranes Na+ partially replaces K+ as an activator of the phosphatase. Although ATP still inhibits phosphatase activity, neither ATP, nor ATP+Na+ are able to modify the apparent affinity for K+ of K+-dependent phosphatase in these membranes.
D000251:Adenosine Triphosphatases / Q000097:blood*; D000255:Adenosine Triphosphate / Q000097:blood; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D004912:Erythrocytes / Q000201:enzymology*; D005033:Ethylmaleimide / Q000494:pharmacology; D006801:Humans; D008274:Magnesium / Q000097:blood*; D009943:Organophosphorus Compounds / Q000097:blood; D010042:Ouabain / Q000494:pharmacology; D010710:Phosphates / Q000097:blood*; D010740:Phospholipases / Q000494:pharmacology*; D011188:Potassium / Q000097:blood*; D012964:Sodium / Q000097:blood; D013268:Stimulation, Chemical
D009943:Organophosphorus Compounds; D010710:Phosphates; D010042:Ouabain; D000255:Adenosine Triphosphate; D012964:Sodium; D010740:Phospholipases; D000251:Adenosine Triphosphatases; D008274:Magnesium; D005033:Ethylmaleimide; D011188:Potassium