A 20-kDa protein associated with the murine T-cell antigen receptor is phosphorylated in response to activation by antigen or concanavalin A.
Antigen or concanavalin A activation of a murine T-cell hybrid specific for pigeon cytochrome c and restricted to the Ek alpha:Ek beta immune response-associated (Ia) molecule resulted in phosphorylation of a 20-kDa protein that was specifically coprecipitated by a monoclonal antibody binding the T-cell antigen receptor. There was no evidence for phosphorylation of the antigen receptor itself. The phosphorylation of the 20-kDa polypeptide was dependent on the concentration of antigen or lectin used to activate the T-cell hybrid and reached a maximum 40 min after the addition of antigen. Moreover, the phosphorylation induced by antigen in the presence of Ia molecule-bearing B cells was specifically blocked by the addition of appropriate anti-Ia molecule monoclonal antibodies. The 20-kDa protein was also radioiodinated with a hydrophobic photoactivatable labeling reagent. The amount of iodinated 20-kDa protein immunoprecipitable with the anti-receptor antibody did not increase with T-cell activation, indicating that the phosphorylation occurred on a molecule that was constitutively associated with the antigen receptor. Concanavalin A also induced phosphorylation of a 20-kDa polypeptide in a second antigen-specific major histocompatibility complex-restricted T-cell hybrid. Again, the phosphorylated polypeptide was precipitated only by a monoclonal antibody specific for the antigen receptor on this hybrid. Thus, the antigen or concanavalin A-induced activation of T-cell hybrids results in the rapid phosphorylation of a 20-kDa protein that is associated with the T-cell antigen receptor.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000941:Antigens / Q000276:immunology; D003208:Concanavalin A / Q000494:pharmacology; D008213:Lymphocyte Activation; D010761:Phosphorus Radioisotopes; D010766:Phosphorylation; D011494:Protein Kinases / Q000032:analysis; D011506:Proteins / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D000941:Antigens; D010761:Phosphorus Radioisotopes; D011506:Proteins; D011948:Receptors, Antigen, T-Cell; D003208:Concanavalin A; D011494:Protein Kinases