ABSTRACT
Integrin αIIbβ3, which is expressed only in megakaryocytes and platelets, is essential for normal platelet adhesion and aggregation during hemostasis and for the development of occlusive, platelet-rich thrombi in vascular diseases. Platelets are anucleate cells and consequently are not amenable to study by the usual recombinant methods. The chapter describes the principal methods to characterize αIIbβ3 signaling in CHO cells. Affinity modulation refers to that aspect of inside-out signaling that facilitates ligand binding by causing conformational changes within individual αIIbβ3 heterodimers, resulting in the formation and/or exposure of ligand binding sites in the extracellular domain of the receptor. Receptor clustering is typically initiated from outside the cell by antibody crosslinking.
