Molecular Dissection of T-Cell Antigen Receptor Signal Transduction
Antigen recognition by mature and immature T-cells induces a cascade of events which ultimately leads to a variety of cellular responses (Weiss 1991). One of the major features of this signal transduction pathway is the tyrosine phosphorylation of several cytoplasmic and membrane proteins. Both kinetic studies and analyses using tyrosine kinase inhibitors showed that one of the earliest events in T-cell activation involves tyrosine kinases (June et al. 1990 a, b). PLC-γ1 is one of the substrates of this tyrosine kinase activity induced by T cell antigen receptor (TCR) stimulation (Weiss et al 1991b) This phosphorylation activates the enzyme and induces the catalysis of phosphatidylinositol 4,5-bisphosphate (PIP2) into diacylglycerol and inositol 1,4,5-trisphosphate (IP3), which activate PKC and mobilize intracellular calcium, respectively (Rhee et al 1989; Nishibe S et al 1990).
KeywordsTyrosine Phosphorylation Protein Tyrosine Kinase Cytoplasmic Tail Kinase Assay Signaling Capability
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