Mechanism of platelet agglutination and activation induced by echicetin-IgM complex or biotinylated echicetin/avidin.

Echicetin binds to GPIb. (A) One molecule of IgMκ can bind up to 5 molecules of echicetin. Binding of several molecules to the surface of one platelet results in clustering of GPIb molecules (1). Binding of echicetin molecules attached to the surface of different platelets results in agglutination (2). (B) One molecule of avidin can bind up to 4 molecules of biotin. Binding of several molecules of biotinylated echicetin to the surface of one platelet results in clustering of GPIb molecules (1). Binding of biotinylated echicetin molecules attached to the surface of different platelets results in agglutination (2).