p56lck interacts via its src homology 2 domain with the ZAP-70 kinase.
p56lck, a member of the src family of protein tyrosine kinases, is an essential component in T cell receptor (TCR) signal transduction. p56lck contains a src homology 2 (SH2) domain found in a number of proteins involved in intracellular signaling. SH2 domains have been implicated in protein-protein interactions by binding to sequences in target proteins containing phosphorylated tyrosine. Using an in vitro assay, we have studied specific binding of tyrosine-phosphorylated proteins to a recombinant p56lck SH2 domain. In nonactivated Jurkat cells, two tyrosine-phosphorylated proteins were detected. Stimulation with anti-CD3 monoclonal antibodies induced the binding of seven additional tyrosine-phosphorylated proteins to the SH2 domain of p56lck. We have identified the zeta-associated tyrosine kinase, ZAP-70, as one of these proteins. Evidence suggests that binding of ZAP-70 to p56lck SH2 is direct and not mediated by zeta. The significance of this interaction was further investigated in vivo. p56lck could be coprecipitated with the zeta/ZAP-70 complex and conversely, ZAP-70 was detected in p56lck immunoprecipitates of activated Jurkat cells. The physical association of p56lck and ZAP-70 during activation supports the recently proposed functional cooperation of these two tyrosine kinases in TCR signaling.
Duplay
P
P
Department of Immunology, Institut Pasteur, Paris, France.
Thome
M
M
Hervé
F
F
Acuto
O
O
D001483:Base Sequence; D017252:CD3 Complex / Q000276:immunology; D002460:Cell Line; D004247:DNA; D006801:Humans; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D008969:Molecular Sequence Data; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D017385:Sequence Homology; D015398:Signal Transduction; D051746:ZAP-70 Protein-Tyrosine Kinase
D017252:CD3 Complex; D011948:Receptors, Antigen, T-Cell; D004247:DNA; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051746:ZAP-70 Protein-Tyrosine Kinase; C497261:ZAP70 protein, human