Summary

Because of its major role in regulating platelet functions and itsprominence on the cell surface, integrin a_IIbb₃ has been the subject ofintensive investigations. Such studies have provided substantial insightsinto its structure-function relationships and have led to the developmentof anti-thrombotic drugs that target the receptor. Nevertheless,recent findings have indicated that our understanding of the structureand function of a_IIbb₃ remains inadequate. This article addresses twoaspects of still evolving a_IIbb₃ function: 1) the interface between a_IIbb₃and the blood coagulation system, resulting from interaction of prothrombinwith the receptor; and 2) the molecular basis for recognitionof the RGD and the fibrinogen g-chain peptide ligands by a_IIbb₃. Asillustrated by these two examples, there is still much to be learnedabout a_IIbb₃ if we are to fully appreciate its functions and its potentialas a therapeutic target.