Syk and ZAP-70 mediate recruitment of p56lck/CD4 to the activated T cell receptor/CD3/zeta complex.
During antigen recognition by T cells, CD4 and the T-cell receptor (TCR)/CD3/zeta complex are thought to interact with the same major histocompatibility complex II molecule in a stable ternary complex. Evidence has suggested that the association of CD4 with TCR/CD3/zeta requires the interaction of the protein tyrosine kinase p56lck with CD4. We have taken a biochemical approach to understand the mechanism by which p56lck and, in particular, its src homology (SH) 2 domain contributes to the association of CD4 with TCR/CD3/zeta during activation. We have previously shown that the p56lck SH2 domain binds directly to tyrosine-phosphorylated ZAP-70. Here we formally demonstrate the in vivo association of p56lck with the homologous protein tyrosine kinases Syk and ZAP-70 after CD3 stimulation of Jurkat cells. A tyrosine-phosphorylated peptide containing the sequence predicted to be optimal for binding to the SH2 domain of src family kinases specifically competes for this association, indicating that tyrosine-phosphorylated ZAP-70 and Syk bind to p56lck by an SH2-mediated interaction. We also show that the same peptide is able to compete for the activation-dependent TCR/CD4 association in Jurkat cells. Moreover, ZAP-70 and CD4 cocap only after CD3 stimulation in human T lymphoblasts. We propose that the interaction of the p56lck SH2 domain with zeta-associated tyrosine-phosphorylated ZAP-70 and/or Syk enables CD4 to associate with antigen-stimulated TCR/CD3/zeta complexes.
Thome
M
M
Department of Immunology, Institut Pasteur, Paris, France.
Duplay
P
P
Guttinger
M
M
Acuto
O
O
D015703:Antigens, CD / Q000276:immunology*; D015704:CD4 Antigens / Q000276:immunology*; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D004792:Enzyme Precursors / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D008213:Lymphocyte Activation; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D008565:Membrane Proteins / Q000276:immunology*; D010766:Phosphorylation; D019000:Phosphotyrosine; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000302:isolation & purification / Q000378:metabolism*; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D000072377:Syk Kinase; D013601:T-Lymphocytes / Q000276:immunology*; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis; D051746:ZAP-70 Protein-Tyrosine Kinase
D015703:Antigens, CD; D015704:CD4 Antigens; D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D011948:Receptors, Antigen, T-Cell; C054979:antigen T cell receptor, zeta chain; D019000:Phosphotyrosine; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); C000606896:SYK protein, human; D000072377:Syk Kinase; D051746:ZAP-70 Protein-Tyrosine Kinase; C497261:ZAP70 protein, human