alpha(IIb)beta(3) and its antagonism at the new millennium

Because of its major role in regulating platelet functions and its prominen ce on the cell surface, integrin alpha (IIb)beta (3) has been the subject o f intensive investigations. Such studies have provided substantial insights into its structure-function relationships and have led to the development of anti-thrombotic drugs that target the receptor. Nevertheless, recent fin dings have indicated that our understanding of the structure and function o f alpha (IIb)beta (3) remains inadequate. This article addresses two aspect s of still evolving alpha (IIb)beta (3) function: 1) the interface between alpha (IIb)beta (3) and the blood coagulation system, resulting from intera ction of prothrombin with the receptor; and 2) the molecular basis for reco gnition of the RGD and the fibrinogen gamma -chain peptide ligands by alpha (IIb)beta (3). As illustrated by these two examples, there is still much t o be learned about alpha (IIb)beta (3) if we are to fully appreciate its fu nctions and its potential as a therapeutic target.