ACTIVATION OF EPIDERMAL GROWTH FACTOR RECEPTOR

这个项目的长期目标是阐明所有的步骤 表皮生长因子（EGF） 激活表皮生长因子受体（EGF）的酪氨酸激酶 受体）。 细胞内各种蛋白质的磷酸化， 这种酪氨酸激酶启动一系列事件， 分裂与成长 研究表明，含有某些 EGF受体的突变形式在转化状态下不受控制地生长 某些病毒致癌基因是这种细胞的病毒形式的改变， 受体的 这些观察结果表明，这种蛋白质可能是一个点， 异常致癌生长的起始点。 EGF受体的激活机制涉及EGF的结合， EGF受体的二聚化，酪氨酸激酶的活化，和 受体的自我磷酸化。 这些步骤中的每一步都将 详细检查。 EGF单体和二聚体形式的亲和力 表皮生长因子受体将被测量，以确定是否 单体EGF受体的二聚化和酪氨酸的激活 激酶与这种结合有关。 二阶速率常数为 将测量胞外结构域的二聚化， 可以直接与完整蛋白质的二聚化进行比较。 我们 将在完整的细胞质结构域中寻找构象变化， EGF受体是通过结合EGF而启动的，但先于 二聚化。 EGF受体的游离胞质结构域将被 用二价免疫球蛋白二聚化，以观察二聚化是否是 足以激活酪氨酸激酶。 的激活 缺乏所有自我磷酸化位点的截短的EGF受体将 进行研究，以验证在合成过程中对二聚的要求。 即使在没有自我磷酸化的情况下也能激活。 的能力 EGF受体的启动子，使其在活化的二聚体中磷酸化 将被评估。 自我磷酸化的进程将是 与酪氨酸的二聚化和活化在时间上相关 激酶。 EGF受体二聚化的可逆性及EGF受体的表达 将检测酪氨酸激酶的活化。 的结果 这些实验将增加我们对各种步骤的理解， 这种生长因子受体的激活机制。

The long term objective of this project is to elucidate all of the steps in the molecular mechanism by which epidermal growth factor (EGF) activates the tyrosine kinase of epidermal growth factor receptor (EGF receptor). The phosphorylation of various proteins within the cell by this tyrosine kinase initiates a cascade of events leading to cell division and growth. It has been shown that cells containing certain mutant forms of EGF receptor grow uncontrollably in a transformed state and certain viral oncogenes are altered viral forms of this cellular receptor. These observations suggest that this protein could be a point of initiation for abnormal oncogenic growth. The mechanism of activation of EGF receptor involves binding of EGF, dimerization of the EGF receptor, activation of the tyrosine kinase, and self-phosphorylation of the receptor. Each of these steps will be examined in detail. the affinity of monomeric and dimeric forms of EGF receptor for EGF will be measured to determine whether or not dimerization of monomeric EGF receptor and activation of the tyrosine kinase is linked to this binding. The second-order rate constant for the dimerization of the extracellular domain will be measured so that it can be compared directly to that for dimerization of the intact protein. We will look for conformational changes in the cytoplasmic domain of intact EGF receptor that are initiated by binding EGF but that precede dimerization. The free cytoplasmic domain of EGF receptor will be dimerized with bivalent immunoglobulins to see if dimerization is sufficient to activate the tyrosine kinase. the activation of a truncated EGF receptor lacking all of the self-phosphorylation sites will be studied to verify the requirement for dimerization in the process of activation even in the absence of self-phosphorylation. The ability of a promoter of EGF receptor to phosphorylate itself in the activated dimer will be assessed. The progress of self-phosphorylation will be correlated temporally with dimerization and activation of the tyrosine kinase. The reversibility of the dimerization of EGF receptor and the activation of the tyrosine kinase will be examined. The results from these experiments will increase our understanding of the various steps in the mechanism of activation of this growth factor receptor.