Stimulation of human platelets with concanavalin A involves phospholipase C activation.
In response to concanavalin A, cytoplasmic calcium movement was observed in human platelets, both in the presence of 1 mM Ca2+ or 1 mM EGTA in the medium. Concanavalin A also caused the activation of inositide turnover and the production of inositol phosphates, suggesting that activation of phospholipase C occurs. The mechanism by which concanavalin A stimulates phospholipase C does not depend on GTP-binding transducers, because it was not inhibited by GDP beta S, while experiments performed in the presence of cytochalasin B suggested a role for membrane glycoprotein IIb-IIIa-cytoskeleton interaction in this process. Ca(2+)-proteases and Na+/H+ antiport also seemed to be related to concanavalin A-induced phospholipase C activation, as suggested by experiments performed in the presence of leupeptin and amiloride.
Torti
M
M
Department of Biochemistry, Faculty of Sciences, University of Pavia, Italy.
Balduini
C
C
Ramaschi
G
G
Sinigaglia
F
F
D001692:Biological Transport; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D003208:Concanavalin A / Q000494:pharmacology*; D003571:Cytochalasin B / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D004789:Enzyme Activation; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D007295:Inositol Phosphates / Q000032:analysis; D015539:Platelet Activation / Q000187:drug effects*; D015398:Signal Transduction; D013873:Thionucleotides / Q000494:pharmacology; D010738:Type C Phospholipases / Q000187:drug effects / Q000378:metabolism*
D007295:Inositol Phosphates; D013873:Thionucleotides; D003208:Concanavalin A; D006153:Guanosine Diphosphate; D003571:Cytochalasin B; C023427:guanosine 5'-O-(2-thiodiphosphate); D010738:Type C Phospholipases; D002118:Calcium