A novel C-lectin protein, lebecetin, was purified and characterized from the venom of Macrovipera lebetina. It is a disulfide-linked heterodimer of 15 and 16 kD. The subunits are homologous to each other and to the other snake venom proteins of the C-type (Ca(2+)-dependent) lectin superfamily. Lebecetin shows a potent inhibitory effect on whole blood and washed platelets induced by different ag...