GRB2 and phospholipase C-gamma 1 associate with a 36- to 38-kilodalton phosphotyrosine protein after T-cell receptor stimulation.

摘要: Abstract GRB2, a 25-kDa protein comprising single SH2 domain flanked by two SH3 domains, has been implicated in linking receptor tyrosine kinases (PTKs) to the Ras pathway interacting with guanine nucleotide exchange SOS. Previous studies have demonstrated that GRB2 directly interacts Shc, proto-oncogene product is phosphorylated upon and nonreceptor PTK activation. In this report, we detected low levels of phosphorylation Shc induced association T-cell (TCR) stimulation. Instead, prominent 36- 38-kDa phosphoprotein (pp36-38) associated formed stable complex GRB2/SOS TCR Cellular fractionation showed whereas both SOS partitioned soluble particulate fractions, pp36-38 was present exclusively fraction. This had same apparent mobility sodium dodecyl sulfate-polyacrylamide gel electrophoresis as associates phospholipase C-gamma 1 (PLC-gamma 1). Furthermore, following partial immunodepletion pp36-38, there significant reduction amount 36-kDa PLC-gamma 1, suggesting trimeric 1/pp36-38/GRB2 could form. support notion, also able detect immunoprecipitates. We suggest may be bridging protein, coupling different signalling molecules cytoplasmic PTKs regulated TCR.