Key result
Convulxin induces human platelet adhesion and activation by binding to glycoprotein VI, with integrin alpha2beta1 involved in the later stages of exocytosis and aggregation.
Demonstrates that convulxin activates human platelets via the glycoprotein VI receptor, with alpha2beta1 integrin mediating subsequent exocytosis and aggregation.
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Offers preclinical insight into platelet receptor pathways; leaves open whether GPVI or alpha2beta1 targeting alters thrombosis outcomes.
We analyzed the interaction of convulxin (Cvx), a 72-kDa protein isolated from the venom of Crotalus durissus terrificus, with human platelets. Cvx is a potent platelet agonist that induces an increase in the intracellular Ca2+ concentration ([Ca2+]i), granule exocytosis and aggregation. 125I-Labeled Cvx binds specifically and rapidly to platelets at binding sites of high and moderate affinity. Platelets adhere to immobilized Cvx in a time-dependent but cation-independent manner. Platelet exocytosis and aggregation induced by Cvx were inhibited by an anti-integrin alpha2beta1 monoclonal antibody (6F1) and by the Fab fragments of a polyclonal anti-glycoprotein VI (GPVI) antibody. Both the adhesion of platelets to Cvx and the Cvx-induced increase in [Ca2+]i were inhibited by anti-GPVI Fab fragments but not by 6F1. Ligand blotting assay showed that 125I-Cvx binds to a 57-kDa platelet protein with an electrophoretic mobility identical to that of GPVI. In addition, we observed the following: (i) 125I-Cvx binds to GPVI immunoprecipitated by the anti-GPVI antibody from a platelet lysate, and (ii) Cvx inhibits the binding of anti-GPVI IgG to GPVI. Taken together, these results demonstrate that GPVI behaves as a Cvx receptor and that the alpha2beta1 integrin appears to be involved in the later stages of Cvx-induced platelet activation, i.e. exocytosis and aggregation.
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Jandrot‐Perrus et al. (1997) studied this question. Convulxin (Cvx) was evaluated on Platelet adhesion, activation, and binding. Convulxin induces human platelet adhesion and activation by binding to glycoprotein VI, with integrin alpha2beta1 involved in the later stages of exocytosis and aggregation.
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