Wange R L, Malek S N, Desiderio S, Samelson L E
Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892.
J Biol Chem. 1993 Sep 15;268(26):19797-801.
A proximal and critical biochemical event upon T cell antigen receptor (TCR) stimulation is the activation of a protein tyrosine kinase (PTK) pathway. ZAP-70, a PTK of the p72syk family, associates with phosphorylated TCR subunits upon TCR stimulation. Here we report that the tandem SH2 domains of ZAP-70, expressed as a fusion protein, bind to tyrosine-phosphorylated CD3 epsilon and TCR zeta from activated Jurkat T cell lysates. The single N- and C-terminal SH2 domains of ZAP-70, expressed separately, do not bind these TCR subunits. In comparison to fusion proteins containing SH2 domains from other proteins, the tandem SH2 domains of ZAP-70 demonstrate a remarkably restricted repertoire of protein binding, binding only TCR zeta and CD3 epsilon. ZAP-70 is also recovered in the binding assay, but this is likely to be a consequence of its interaction with multiple SH2 binding sites on the zeta-zeta and CD3 epsilon-containing dimers.
T细胞抗原受体（TCR）受刺激后，近端且关键的生化事件是蛋白酪氨酸激酶（PTK）途径的激活。ZAP-70是p72syk家族的一种PTK，在TCR受刺激时与磷酸化的TCR亚基结合。在此我们报告，以融合蛋白形式表达的ZAP-70串联SH2结构域，可与活化的Jurkat T细胞裂解物中的酪氨酸磷酸化CD3ε和TCRζ结合。单独表达的ZAP-70的单个N端和C端SH2结构域不与这些TCR亚基结合。与含有其他蛋白SH2结构域的融合蛋白相比，ZAP-70的串联SH2结构域显示出非常有限的蛋白结合谱，仅结合TCRζ和CD3ε。在结合试验中也回收了ZAP-70，但这可能是其与含ζ-ζ和CD3ε的二聚体上多个SH2结合位点相互作用的结果。
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