Characterization of the cross-linking site of disintegrins albolabrin, bitistatin, echistatin, and eristostatin on isolated human platelet integrin GPIIb/IIIa.

Disintegrins, a family of low molecular weight, RGD-containing peptides found in snake venoms prevent the binding of adhesive ligands to a number of integrin receptors. Albolabrin, bitistatin, echistatin, and eristostatin bind to the platelet fibrinogen receptor (GPIIb/IIIa) acting thus as potent inhibitors of platelet aggregation. Here, we have determined the cross-linking of these disintegrins on isolated GPIIb/IIIa. The cross-linking site of all of them was within GPIIIa 217-302, a domain that has been implicated in a number of receptor functions including heterodimer association, activation-dependent conformational changes, and fibrinogen binding.