title: The p56lck SH2 domain mediates recruitment of CD8/p56lck to the activated T cell receptor/CD3/zeta complex.
abstract: The CD4 or CD8 co-receptors and the T cell receptor (TCR) are though to interact with the same antigen-presenting major histocompatibility complex molecule in a stable ternary complex. Therefore, the TCR and its co-receptor need to come into close proximity on the surface of the T cell. We have previously shown that the interaction of the p56lck SH2 domain with zeta-associated, tyrosine phosphorylated ZAP-70 and Syk kinases leads to an enhanced association of CD4 with TCR/CD3/zeta complex after CD3 stimulation of Jurkat cells. In this report, we analyzed whether a similar mechanism can mediate recruitment of the CD8 alpha alpha and CD8 alpha beta isoforms to the TCR. We demonstrate in vivo in association of CD8 alpha alpha/p56lck with the tyrosine kinase ZAP-70 after CD3 stimulation of Jurkat cells. A phosphopeptide competing in vitro for the binding of tyrosine phosphorylated proteins to the SH2 domain of p56lck specifically impedes the association of ZAP-70 with CD8 alpha alpha/p56lck without affecting the zeta/ZAP-70 interaction. The same peptide is able to compete for the activation-dependent association of the CD8 alpha alpha or CD8 alpha beta isoform with the TCR/CD3/zeta complex. Moreover, co-precipitation of the TCR with both CD8 isoforms was observed after CD3 stimulation. These findings strongly suggest that the p56lck SH2 domain mediates recruitment of CD8/p56lck to the activated TCR/CD3/zeta complex.
authors.affiliation: Department of Immunology, Pasteur Institute, Paris France.
authors.forename: M
authors.initials: M
authors.lastname: Thome
authors.forename: V
authors.initials: V
authors.lastname: Germain
authors.forename: J P
authors.initials: JP
authors.lastname: DiSanto
authors.forename: O
authors.initials: O
authors.lastname: Acuto
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016827:CD8 Antigens / Q000502:physiology*; D002460:Cell Line; D006801:Humans; D008213:Lymphocyte Activation; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D008565:Membrane Proteins / Q000502:physiology*; D008969:Molecular Sequence Data; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D011817:Rabbits; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000502:physiology*; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D013601:T-Lymphocytes / Q000276:immunology*; D051746:ZAP-70 Protein-Tyrosine Kinase; D018909:src Homology Domains / Q000502:physiology*; D019061:src-Family Kinases / Q000502:physiology*
chemical_list: D016827:CD8 Antigens; D008565:Membrane Proteins; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D011948:Receptors, Antigen, T-Cell; C054979:antigen T cell receptor, zeta chain; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051746:ZAP-70 Protein-Tyrosine Kinase; C497261:ZAP70 protein, human; D019061:src-Family Kinases