| In this paper , we examined whether Syk was involved in EpoR activation . ^^^ Coimmunoprecipitation experiments showed that the phosphorylated EpoR was associated with the Syk kinase in activated UT 7 cells . ^^^ The use of recombinant Syk Src homology 2 ( SH 2 ) domains expressed in tandem or individually revealed that both N and C SH 2 domains of Syk participated in EpoR binding with a major contribution of the C terminal SH 2 domain . ^^^ Far Western blotting further indicated that Syk directly binds to the EpoR and that the interaction of Syk with EpoR only occurred after Epo activation . ^^^ These data suggest that phosphorylation of EpoR on tyrosine residues may mediate Syk binding to the receptor through interaction between the two SH 2 domains of Syk and tyrosines of the receptor . ^^^ |