ISOLATION AND CHARACTERIZATION OF THE EGF RECEPTOR PUTATIVE SUBSTRATE, EPS8

表皮生长因子(EGF)与其受体结合激活 受体的酪氨酸激酶活性。随后。受刺激的人 受体使自身和其他细胞内蛋白磷酸化。这些 细胞内蛋白统称为EGF受体酪氨酸 酶底物。开发了一种分离这些底物的方法。 获得了多个克隆。他们被指定为EGF的每股收益 受体途径底物。从NIH/3T3细胞的cDNA文库中获得。其中之一 这些克隆Eps8编码一种97 kDa的蛋白质。结果表明，EPS8 也被激活的EGF受体酪氨酸激酶磷酸化 和其他酪氨酸激酶一样。EPS8与EGF受体直接结合。 尽管没有SH2结构域。委员会进一步确定， Eps8的区域对于它与EGF受体的相互作用是重要的。 重组Eps8在成纤维细胞或造血细胞中的过表达 增加细胞对促有丝分裂作用的反应和敏感性 EGF。因此，Eps8可能参与了EGF的转导。 信号。序列分析显示在Eps8中有一个SH3结构域。65 kDa 鉴定出与Eps8的SH3结构域结合的蛋白质，并显示 这种蛋白质主要分布在细胞的核部分。 手机。

Binding of epidermal growth factor (EGF) to its receptor activates the receptor's tyrosine kinase activity. Subsequently. the stimulated receptor phosphorylates itself and other intracellular proteins. These intracellular proteins are collectively termed EGF receptor tyrosine kinase substrates. A method was developed to isolate these substrates and several cDNA clones were obtained. They were designated eps for EGF receptor pathway substrate. from an NIH/3T3 cell cDNA library. One of these clones, eps8, encodes a protein of 97 kDa. It was shown that eps8 was phosphorylated by the activated EGF receptor tyrosine kinase as well as by other tyrosine kinases. eps8 binds to the EGF receptor directly. despite the absence of a SH2 domain. It was further determined that the regions of eps8 are important for its interaction with the EGF receptor. Overexpression of recombinant eps8 in fibroblasts or hematopoietic cells increases the cells response and sensitivity to the mitogenic action of EGF. Therefore, eps8 is likely involved in the transduction of EGF signals. Sequence analysis revealed a SH3 domain in eps8. A 65 kDa protein was identified that binds to the SH3 domain of eps8 and showed that this protein is mainly distributed in the nuclear fraction of the cell.