A membrane-bound phospholipase C with an apparent specificity for lysophosphatidylinositol in porcine platelets.
A membrane preparation from porcine platelets catalyzed the hydrolysis of [2-3H]glycerol-labeled lysophosphatidylinositol to form monoacylglycerol and inositol phosphates. The hydrolysis was optimal at pH 9. The addition of Ca2+ did not enhance the hydrolysis, but the enzyme was inhibited completely by EGTA. The EGTA-inactivated enzyme was partially reactivated by Ca2+; Mn2+, Mg2+, and Zn2+ were much less effective or ineffective for the reactivation. The phospholipase C was apparently specific for lysophosphatidylinositol; phosphatidylinositol, phosphatidylcholine, phosphatidylethanolamine, lysophosphatidylcholine, lysophosphatidylethanolamine, phosphatidic acid, and lysophosphatidic acid were not hydrolyzed at significant rates under the conditions used. Phospholipase C with these properties has not been reported previously.
D000818:Animals; D001792:Blood Platelets / Q000201:enzymology*; D002413:Cations, Divalent; D002462:Cell Membrane / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D004533:Egtazic Acid / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008244:Lysophosphatidylcholines / Q000097:blood*; D010740:Phospholipases / Q000097:blood*; D013379:Substrate Specificity; D013552:Swine; D010738:Type C Phospholipases / Q000097:blood*
D002413:Cations, Divalent; D008244:Lysophosphatidylcholines; D004533:Egtazic Acid; D010740:Phospholipases; D010738:Type C Phospholipases