title: Functional activation of the T-cell antigen receptor induces tyrosine phosphorylation of phospholipase C-gamma 1.
abstract: Stimulation of the T-cell antigen receptor (TCR), which itself is not a protein-tyrosine kinase (PTK), activates a PTK and phospholipase C (PLC). Using the human T-cell leukemic line Jurkat and normal peripheral blood lymphocytes, we demonstrate that stimulation of the TCR specifically induces the recovery of PLC activity in eluates from anti-phosphotyrosine immunoprecipitates. Stimulation of the human muscarinic receptor, subtype 1, when expressed in Jurkat activates PLC through a guanine nucleotide binding protein but does not induce the recovery of PLC activity in eluates from anti-phosphotyrosine immunoprecipitates. Western blot analysis reveals that PLC-gamma 1 is tyrosine-phosphorylated in response to TCR stimulation. Nearly all of the PLC activity recovered in eluates from anti-phosphotyrosine immunoprecipitates was depleted by anti-PLC-gamma 1 antibodies. Stimulation of the TCR on mutants derived from Jurkat that are defective in TCR-induced PLC activation results in markedly reduced, if any, PLC activity recovered in phosphotyrosine immunoprecipitates and in no detectable PLC-gamma 1 tyrosine phosphorylation. Thus, the TCR functions like PTK growth factor receptors, but through an indirect interaction, to induce tyrosine phosphorylation of PLC-gamma 1. Since other studies have implicated two members of the src family of PTKs in TCR-mediated signal transduction, our findings suggest that the induction of tyrosine phosphorylation of PLC-gamma 1 by a mechanism involving a src-like kinase may be the means by which the TCR regulates PLC activity in T cells.
authors.affiliation: Howard Hughes Medical Institute, Department of Medicine, University of California, San Francisco 94143.
authors.forename: A
authors.initials: A
authors.lastname: Weiss
authors.forename: G
authors.initials: G
authors.lastname: Koretzky
authors.forename: R C
authors.initials: RC
authors.lastname: Schatzman
authors.forename: T
authors.initials: T
authors.lastname: Kadlecek
mesh_terms: D000911:Antibodies, Monoclonal; D006801:Humans; D066298:In Vitro Techniques; D007295:Inositol Phosphates / Q000502:physiology; D010766:Phosphorylation; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000502:physiology; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000378:metabolism*; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D007295:Inositol Phosphates; D011948:Receptors, Antigen, T-Cell; D019000:Phosphotyrosine; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D010738:Type C Phospholipases