Consistent with this observation , pp 55 selectively binds to isolated SH 2 domains of Lck , Lyn , Src , and Fyn but not to the SH 2 domains of ZAP 70 , Syk , Shc , SLP 76 , Grb 2 , phosphatidylinositol 3 kinase , and c abl in vitro . ^^^
Mutational analysis revealed that tyrosine 271 in SKAP 55 played a pivotal role for interaction with both Fyn kinase and adapter protein Grb 2 , indicating that the Fyn phosphorylated SKAP 55 transiently associates with adapter Grb 2 to mediate mitogen activated protein kinase activation . ^^^ Anti CD 3 stimulation also promoted the interaction of SKAP 55 with Grb 2 in T cells . ^^^