Src homology 2 domains of Syk and Lyn bind to tyrosine-phosphorylated subunits of the high affinity IgE receptor.

摘要: Aggregation of the high affinity IgE receptor (Fc epsilon RI) on rat basophilic leukemia RBL-2H3 cells results in activation protein tyrosine kinases Syk and Lyn. Here, we report that fusion proteins containing Src homology 2 (SH2) domains Lyn precipitated tyrosine-phosphorylated from cell lysates. There was no detectable precipitation with N-terminal SH2 domain, minimal C-terminal SH2, strong when two were expressed tandem. The showed pronounced selectivity binding proteins. Thus, only three phosphoproteins, which beta gamma subunits Fc RI. In contrast, addition to precipitating same RI components, bound many other phosphoproteins. Tyrosine phosphorylation essential for their By direct studies, there more than beta, whereas beta. competitively inhibited association lysates activated cells. SH2-mediated these could play an important role signaling.