Integrins are cell adhesions proteins. We are working on structures and interactions of cytosolic proteins involved in binding to cytosolic tail region of b2 integrins. Dok1 has been shown to be a negative regulator of integrins. The PTB domain of Dok1 binds to NPXY motif of b3 integrin in a phosphorylated manner. This sequence motif is NPXF in b2 integrins. We found that Ser phosphorylation of b2 cytosolic tail induces binding to the PTB domain of Dok1. We will present NMR structure of the PTB domain of Dok1 and mapping of b2 phosphorylated tail.