The protein tyrosine kinase ZAP-70 can associate with the SH2 domain of proto-Vav.
Stimulation of the T cell antigen receptor (TCR) leads to tyrosine phosphorylation of a number of cellular proteins, including the vav proto-oncogene product. We now report the detection of several phosphotyrosine proteins (80, 74, and 70 kDa) from TCR-stimulated T cells that bind to the Src homology 2 (SH2) domain of proto-Vav (Vav-SH2) and co-immunoprecipitate with the proto-Vav product. Their binding to Vav-SH2 differs from that observed with SH2 domains from other proteins. None of the Vav-SH2-associated phosphoproteins bind to either of the Src homology 3 (SH3) domains of proto-Vav or to mutant Vav-SH2 proteins. The association of the phosphoproteins with Vav-SH2 requires induction of tyrosine phosphorylation of cellular proteins since proteins from lysates of herbimycin A-treated TCR-activated T cells fail to associate with Vav-SH2. Among the proteins from T cells that co-immunoprecipitate with the proto-Vav product and bind to its SH2 domain, specific antibodies identified the 70-kDa tyrosine phosphoprotein as ZAP-70, a protein tyrosine kinase (PTK) involved in TCR signal transduction. Binding of this PTK to Vav-SH2 is inhibited by a ZAP-70-specific synthetic tyrosine phosphopeptide. We suggest that ZAP-70 may function as a PTK for proto-Vav.
Katzav
S
S
Lady Davis Institute, Jewish General Hospital, Montreal, Canada.
Sutherland
M
M
Packham
G
G
Yi
T
T
Weiss
A
A
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D017931:DNA Primers; D005982:Glutathione Transferase / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D010748:Phosphopeptides / Q000378:metabolism; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051567:Proto-Oncogene Proteins c-vav; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D051746:ZAP-70 Protein-Tyrosine Kinase
D018797:Cell Cycle Proteins; D017931:DNA Primers; D010748:Phosphopeptides; D011518:Proto-Oncogene Proteins; D051567:Proto-Oncogene Proteins c-vav; D011948:Receptors, Antigen, T-Cell; C496619:Vav1 protein, mouse; D014443:Tyrosine; D005982:Glutathione Transferase; D011505:Protein-Tyrosine Kinases; D051746:ZAP-70 Protein-Tyrosine Kinase; C497262:Zap70 protein, mouse