ISOLATION AND CHARACTERIZATION OF THE EGF RECEPTOR PUTATIVE SUBSTRATE (EPS10).

表皮生长因子（EGF）与其受体的结合激活了表皮生长因子受体。 受体的酪氨酸激酶活性，然后磷酸化本身， 其他细胞内蛋白质。 这些蛋白质统称为EGF。 受体酪氨酸激酶底物。 分离这些激酶的方法 基板已经开发。 该方法涉及分离 通过抗磷酸酪氨酸抗体检测含磷酸酪氨酸蛋白 用EGF处理过的细胞 然后将这些免疫纯化的蛋白质 用于免疫兔以产生特异于 这些蛋白质。 这些抗血清随后被用于筛选 编码EGF的潜在cDNA克隆的表达cDNA文库 受体激酶底物。 在分离的cDNA克隆中，其被命名为eps（表皮 eps10的全长cDNA克隆 编码583个氨基酸的蛋白质。 eps 10的序列分析 发现它与以前鉴定的radixin相同， 与埃兹蛋白高度相似的细胞骨架蛋白 和mosein，这是蛋白质带4.1家族的两个成员。 这三 使用特异性抗体进一步表征相关蛋白， 结果表明，埃兹蛋白是EGF和血小板衍生的 生长因子（PDGF）受体。 Radixin对PDGF受体具有特异性 膜突蛋白不被这两种受体磷酸化。 也是 证明了先前描述的肿瘤移植抗原 是埃兹蛋白。

Binding of epidermal growth factor (EGF) to its receptor activates the receptor's tyrosine kinase activity which then phosphorylates itself and other intracellular proteins. These proteins are collectively termed EGF receptor tyrosine kinase substrates. A method to isolate these kinase substrates has been developed. This method involved the isolation of phosphotyrosine-containing proteins by anti-phosphotyrosine antibodies from cells treated with EGF. These immunopurified proteins were then used to immunize rabbits for the production of antisera specific for these proteins. These antisera were subsequently used to screen expression cDNA libraries for potential cDNA clones encoding the EGF receptor kinase substrates. Among the isolated cDNA clones, which are designated eps (epidermal receptor putative substrate), the full-length cDNA clone for eps10 encodes a protein of 583 amino acids. Sequence analysis of eps10 has revealed that it is identical to radixin, a previously identified cytoskeletal protein which shares a high degree of similarity with ezrin and mosein, two members of the band 4.1 family of proteins. These three related proteins were further characterized using specific antibodies and it was shown that ezrin is a substrate for both EGF and platelet-derived growth factor (PDGF) receptor. Radixin is specific for the PDGF receptor and moesin is not phosphorylated by these two receptors. It was also demonstrated that a previously described tumor transplantation antigen of the methylcholanthrene-induced sarcoma is ezrin.