title: Antigen activation of murine T cells induces tyrosine phosphorylation of a polypeptide associated with the T cell antigen receptor.
abstract: The antigen receptor complex on murine MHC class II-restricted T cells consists of disulfide-linked alpha and beta chains noncovalently associated with four additional polypeptides, two that are endoglycosaminidase F-sensitive, gp26 and gp21, and two that are endoglycosaminidase F-resistant, p25 and p16. We demonstrate here that treatment of murine T cell hybridomas with phorbol 12-myristate 13-acetate results in phosphorylation of p25 and gp21 on serine residues. However, activation of cells by antigen results in the phosphorylation of the gp21 chain and a heretofore unidentified 21 kd protein. This newly defined polypeptide, p21, is specifically immunoprecipitated with the antigen receptor complex, is endoglycosaminidase F-resistant, and is itself part of a disulfide-linked molecule. Unlike antigen-induced phosphorylation of gp21, which occurs on serine residues, phosphorylation of p21 occurs uniquely on tyrosine residues.
mesh_terms: D000818:Animals; D000941:Antigens; D007526:Isoelectric Point; D008213:Lymphocyte Activation; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008970:Molecular Weight; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D019000:Phosphotyrosine; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D013601:T-Lymphocytes / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D000941:Antigens; D046911:Macromolecular Substances; D008565:Membrane Proteins; D010750:Phosphoproteins; D011948:Receptors, Antigen, T-Cell; D010768:Phosphoserine; D019000:Phosphotyrosine; D014443:Tyrosine; D013755:Tetradecanoylphorbol Acetate