Integrin adhesion receptors contain an on/off switch that regulates ligand binding affinity and
cell adhesion. The switch from" off" to" on" is commonly referred to as integrin activation. The
objective of this study was to gain insight into the nature of the on/off switch in platelet
integrin α IIb β 3. Here, we show that a select group of the cysteines, located within the
extracellular cysteine-rich domain of the β subunit, remain unpaired. These unpaired
cysteine residues exhibit the properties of a redox site involved in integrin activation …