ECHISTATIN

Uses

Echistatin has been used:

• as an inhibitor of integrin function to study the role of microfibril-associated glycoprotein-1 (Magp1) in the morphogenesis of vascular structures
• for the preparation of microbubbles targeted to αvβ3 integrins in tumor angiogenesis imaging
• as a conjugate to αvβ3 in flow cytometric binding studies

General Description

Echistatin is a single chain 49 amino acid residue protein, which prevents the aggregation of platelets. It has an isoelectric point (pI) of 8.3 and a molecular weight of 5400. This peptide is present in the venom of Echis carinatus, which is a saw-scaled viper. It contains the arginine-glycine-aspartic (RGD) acid sequence, which is present in proteins that bind to glycoprotein IIb/IIIa complex. It shares the proline-arginine-asparagine-proline sequence with the Aα chain of human fibrinogen. This protein is a member of disintegrin family, which prevents cell adhesion. With regards to molecular weight, echistatins are the smallest member of disintegrin family, and contains four isoforms called, α1, α2, β and γ.

Biochem/physiol Actions

Echistatin is a disintegrin, which prevents the aggregation of platelets. They interact with and prevent the binding of fibrinogen to their receptors on the membrane of platelets. It also inhibits platelet aggregation mediated by epinephrine, thrombin, collagen, or platelet-activating factor. Studies in isolated osteoclasts show that this peptide inhibits bone resorption by osteoclasts, most probably by damaging adhesion structures.