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Updated: Jun 19, 2026

Platelet Adhesion and Aggregation Under Flow using Microfluidic Flow Cells
Published on: October 27, 2009
Ligands "activate" integrin alpha IIb beta 3 (platelet GPIIb-IIIa)
X P Du1, E F Plow, A L Frelinger
1Committee on Vascular Biology, Research Institute of Scripps Clinic, La Jolla, California 92037.
Abstract:
Integrin alpha IIb beta 3 (platelet GPIIb-IIIa) binds fibrinogen via recognition sequences such as Arg-Gly-Asp (RGD). Fibrinogen binding requires agonist activation of platelets, whereas the binding of short synthetic RGD peptides does not. We now find that RGD peptide binding leads to changes in alpha IIb beta 3 that are associated with acquisition of high affinity fibrinogen-binding function (activation) and subsequent platelet aggregation. The structural specificities for peptide activation and for inhibition of ligand binding are similar, indicating that both are consequences of occupancy of the same site(s) on alpha IIb beta 3. Thus, the RGD sequence is a trigger of high affinity ligand binding to alpha IIb beta 3, and certain RGD-mimetics are partial agonists as well as competitive antagonists of integrin function.
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