STRUCTURAL CHARACTERIZATION OF PUTATIVE GROWTH FACTOR RECEPTOR GENE C-ERB-2

为了研究信号转导的分子机制 Erb-B-催化活性的转导和调节 2受体蛋白，一系列结构不同的突变体 生成了基因产物的结构域。突变分子 将克隆表达到NIH/3T3细胞中，以评估其 焦点分析中的生物学活性。我们发现两种不同的 结构改变的类别，即NH-2末端删除 和Val659到Glu或Val 659到Asp突变，能够 上调erbB-2产物的转化潜力。 突变蛋白在体外显示酪氨酸水平升高 激酶活性以及体内水平的增加 酪氨酸残基的磷酸化。这些结果表明， 去调节的酪氨酸激酶功能是 ErbB-2受体的致癌活性。我们目前正在调查 酪氨酸自磷酸化在细胞周期调控中的作用 通过分析ErbB-2受体的生物学活性和活性 缺失一种或多种突变蛋白的生化行为 酪氨酸残基被认为是 自动磷酸化。

In order to study the molecular mechanisms involved in signal transduction and regulation of the catalytic activity of the erbB- 2 receptor protein, a series of mutants in different structural domains of the gene product were generated. Mutated molecular clones were expressed into NIH/3T3 cells in order to assess their biologic activity in a focus assay. We found that two different classes of structural alterations, i.e., an NH-2 terminal deletion and a Val 659 to Glu or Val 659 to Asp mutation, are capable of upregulating the transforming potential of the erbB-2 product. Mutant proteins exhibit an increased level of in vitro tyrosine kinase activity as well as an increased level of in vivo phosphorylation on tyrosine residues. These results indicate that deregulated tyrosine kinase function is a major determinant of erbB-2 receptor oncogenic activity. We are currently investigating the role of tyrosine autophosphorylation in the modulation of the erbB-2 receptor catalytic activity by analyzing the biological and biochemical behavior of mutant proteins lacking one or more of the tyrosine residues which are believed to be targets of autophosphorylation.