Stimulus-response coupling in a cell-free platelet membrane system. GTP-dependent release of Ca2+ by thrombin, and inhibition by pertussis toxin and a monoclonal antibody that blocks calcium release by IP3.
The Ca2+-mobilizing action of thrombin was demonstrated in a cell-free platelet membrane system consisting of open sheets of plasma membrane plus sealed membrane vesicles that accumulate Ca2+ and release Ca2+ in response to IP3. Thrombin plus GTP, acting on plasma membrane (not vesicles), produced a soluble factor (destroyed by alkaline phosphatase) that released Ca2+ from the vesicles. This effect of thrombin/GTP was blocked by a monoclonal antibody that binds to vesicles and prevents Ca2+ release by IP3. Pertussis toxin plus NAD ADP-ribosylated plasma membrane polypeptides of 39 and 41 kDa and blocked Ca2+ release by thrombin/GTP, but not by IP3.
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000911:Antibodies, Monoclonal; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000494:pharmacology; D037342:Pertussis Toxin; D013917:Thrombin / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D007295:Inositol Phosphates; D010566:Virulence Factors, Bordetella; D000246:Adenosine Diphosphate Ribose; D015544:Inositol 1,4,5-Trisphosphate; D006160:Guanosine Triphosphate; D037342:Pertussis Toxin; D013917:Thrombin; D019204:GTP-Binding Proteins; D002118:Calcium