A redox site involved in integrin activation

Integrin adhesion receptors contain an on/off switch that regulates ligand binding affinity and cell adhesion. The switch from "off" to "on" is common ly referred to as integrin activation. The objective of this study was to g ain insight into the nature of the on/off switch in platelet integrin alpha (IIb)beta (3). Here, we show that a select group of the cysteines, located within the extracellular cysteine-rich domain of the beta subunit, remain unpaired. These unpaired cysteine residues exhibit the properties of a redo x site involved in integrin activation. Alterations to the redox site preve nt the inter-conversion between resting and active integrin. Altogether, th e study establishes integrin as a direct target for redox modulation, revea ling an unappreciated link between cell adhesion and redox biology.