Stimulation of the high-affinity IgE receptor results in the tyrosine phosphorylation of a 60 kD protein which is associated with the protein-tyrosine kinase, Csk.

摘要: Abstract The protein tyrosine kinase Csk downregulates the activity of Src family kinases and has a negative effect on signal transduction through several kinase-associated receptors. Because Src-family Lyn plays pivotal role in FceRI-mediated cellular activation, we examined whether is involved FceRI signaling events. Using anti-Csk antibodies recombinant fusion proteins detected single tyrosine-phosphorylated 60 kD (herein referred to as ‘p60’) that associates with SH2 domain after stimulation FceRI. p60 phosphorylation reached maximum within one minute remained constant while receptors were aggregated; disaggregation resulted rapid dephosphorylation p60. was only activation by IgE antigen not PMA and\or ionomycin. Phosphorylated associated entirely membrane fraction cells. A considerable both unstimulated stimulated cells, this did change upon activation. coprecipitated from cells phosphorylated immunocomplex. Total immunoprecipitates increased stimulation. react number known molecules, including recently cloned, GAP-associated protein, p62 dok . Our data demonstrate membrane-anchored complex directly Fc e RI transduction.