The platelet integrin αIIbβ3 is required for platelet aggregation. Like other integrins, αIIbβ3 resides on cell surfaces in an equilibrium between inactive and active conformations. Recent experiments suggest that the shift between these conformations involves a global reorganization of the αIIbβ3 molecule and disruption of constraints imposed by the heteromeric association of the αIIb and β3 transmembrane and cytoplasmic domains. The biochemical, biophysical, and ultrastructural results that support this conclusion are discussed in this Review.
Joel S. Bennett