Alterations in tyrosine protein phosphorylation induced by antibody-mediated cross-linking of the CD4 receptor of T lymphocytes.
Accumulating data suggest that the CD4 T-cell surface antigen transduces an independent intracellular signal during antigen-mediated T-cell activation. CD4 is physically associated with the internal membrane tyrosine protein kinase p56lck and can mediate, after antibody-mediated cross-linking, the rapid enzymatic activation of Lck, implying that CD4 signalling may involve changes in tyrosine protein phosphorylation. In this report, we describe that cross-linking of CD4 results in a series of rapid changes in intracellular tyrosine protein phosphorylation. The most prominent CD4-induced tyrosine phosphorylation change involved p56lck, which became extensively phosphorylated on the carboxy-terminal tyrosine residue 505 and, to a lesser extent, lymphocytes can transduce an intracellular signal resulting in tyrosine protein phosphorylation and strongly suggest that this property of CD4 is mediated through p56lck.
Veillette
A
A
McGill Cancer Centre, Montreal, Canada.
Bolen
J B
JB
Bookman
M A
MA
D000818:Animals; D000950:Antigens, Ly / Q000276:immunology / Q000378:metabolism*; D015704:CD4 Antigens / Q000276:immunology*; D003488:Cyanogen Bromide; D051379:Mice; D008970:Molecular Weight; D010748:Phosphopeptides / Q000032:analysis; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011940:Receptor Aggregation / Q000276:immunology / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D013601:T-Lymphocytes / Q000378:metabolism*; D014443:Tyrosine / Q000032:analysis
D000950:Antigens, Ly; D015704:CD4 Antigens; D010748:Phosphopeptides; D010750:Phosphoproteins; D019000:Phosphotyrosine; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D003488:Cyanogen Bromide