Katzav S, Sutherland M, Packham G, Yi T, Weiss A
Lady Davis Institute, Jewish General Hospital, Montreal, Canada.
J Biol Chem. 1994 Dec 23;269(51):32579-85.
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.
T细胞抗原受体（TCR）的刺激会导致多种细胞蛋白发生酪氨酸磷酸化，包括原癌基因vav的产物。我们现在报告，在TCR刺激的T细胞中检测到几种磷酸酪氨酸蛋白（80 kDa、74 kDa和70 kDa），它们与原Vav（Vav-SH2）的Src同源2（SH2）结构域结合，并与原Vav产物进行共免疫沉淀。它们与Vav-SH2的结合不同于其他蛋白的SH2结构域所观察到的情况。Vav-SH2相关的磷酸蛋白均不与原Vav的任何一个Src同源3（SH3）结构域或突变的Vav-SH2蛋白结合。磷酸蛋白与Vav-SH2的结合需要诱导细胞蛋白的酪氨酸磷酸化，因为来自除草霉素A处理的TCR激活的T细胞裂解物中的蛋白无法与Vav-SH2结合。在与原Vav产物进行共免疫沉淀并与其SH2结构域结合的T细胞蛋白中，特异性抗体将70 kDa的酪氨酸磷酸蛋白鉴定为ZAP-70，一种参与TCR信号转导的蛋白酪氨酸激酶（PTK）。这种PTK与Vav-SH2的结合被ZAP-70特异性合成酪氨酸磷酸肽所抑制。我们认为ZAP-70可能作为原Vav的PTK发挥作用。
