T cell receptor XXXX phosphorylation. Variable coupling for different activating ligands.

@entity268 @entity6057 @entity5399 @entity563 @entity669 @entity4357
We have previously reported (Samelson, L.E., Patel, M.D., Weissman, A.M., Harford, J.B., and Klausner, R.D. (1986) Cell 46, 1083-1090) that T cell activation by antigen is associated with activation of two biochemical pathways. In this scheme two protein kinases are activated by stimulation of the @entity6057 ( @entity6057 ). These kinases phosphorylate two different chains of the @entity6057 complex. Protein kinase C is responsible for the phosphorylation of the gamma, and, to a lesser extent, the epsilon chains of the receptor on @entity563 residues while the activation of an unidentified @entity669 kinase leads to phosphorylation of the p21 subunit of the receptor on @entity669 residues. In addition to activation by specific antigens, T cells can be functionally activated in vitro by the addition of antibodies that bind either the antigen receptor or the @entity5399 molecule, an entity independent of the receptor. We have used antibodies directed against these molecules and show that they result in the same dual kinase activation observed with antigen stimulation. In addition we have compared the three ligands, antigen, and antibodies directed against the epsilon chain of the @entity6057 or against @entity5399 , in terms of how they couple to the two kinase pathways. Activation of @entity4357 breakdown and @entity6057 phosphorylation on @entity563 by all three stimuli are sensitive to @entity268 inhibition. In contrast, only antigen-stimulated @entity669 kinase activation is sensitive to @entity268 while the two antibody reagents activate the @entity669 kinase in a manner that is entirely insensitive to @entity268 inhibition.
