| Here we demonstrate that the proposed adapter protein for Src kinases , Sam 68 , is a ligand whose proline rich motifs interact with the SH 3 domains of p 59 ( fyn ) and phospholipase Cgamma 1 as well as with the WW domains of FBP 30 and FBP 21 . ^^^ The asymmetrical dimethylation of arginine residues within these RG repeats dramatically reduces the binding of the SH 3 domains of p 59 ( fyn ) and phospholipase Cgamma 1 , but has no effect on their binding to the WW domain of FBP 30 . ^^^ |