Platelet adenylate cyclase and phospholipase C are affected differentially by ADP-ribosylation. Effects on thrombin-mediated responses.
Thrombin stimulates phospholipase C and inhibits adenylate cyclase in human platelets. We have studied the effect of purified S1 monomer, the ADP-ribosylating subunit of pertussis toxin, on these receptor-coupled G-protein-dependent activities. ADP-ribosylation of a 41 kDa protein is associated with a marked decrease in the ability of thrombin to inhibit cyclic AMP formation, but has little effect on phospholipase C. Therefore adenylate cyclase and phospholipase C appear to be modulated by different G-proteins.
D036002:ADP Ribose Transferases; D000244:Adenosine Diphosphate / Q000097:blood*; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000097:blood*; D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology*; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D010430:Pentosyltransferases / Q000494:pharmacology*; D013917:Thrombin / Q000494:pharmacology; D010738:Type C Phospholipases / Q000097:blood*
D000067956:Adenylyl Cyclase Inhibitors; D000244:Adenosine Diphosphate; D036002:ADP Ribose Transferases; D010430:Pentosyltransferases; D010738:Type C Phospholipases; D013917:Thrombin; D000262:Adenylyl Cyclases