表皮生长因子(epidermal growth factor, EGF) 表皮生长因子是一种小肽,由53个氨基酸残基组成, 是类EGF大家族的一个成员,是一种多功能的生长因子,在体内体外都对多种组织细胞有强烈的促分裂作用。EGF同应答细胞表面的特异受体结合,一旦结合,便促进受体二聚化并使细胞质位点磷酸化。被激活的受体至少可与5种具有不同信号序列的蛋白结合,进行信号转导,在翻译水平上对蛋白质的合成起调节作用。此外EGF可提高细胞内DNA拓扑异构酶活性,也可促进一些与增殖有关的基因表达,如myc 、fos等。 EGF exerts its signals through the EGF Receptor and its hetero-oligomerization partners, members of the ErbB family. The Receptors are transmembrane tyrosine kinases which are activated as a consequence of ligand-induced dimerization. Every EGF molecule has two receptor-binding sites, so the activated ligand-receptor complex consists of two molecules of EGF and two receptor molecules. Receptor autophosphorylation activates the intrinsic kinase activity towards heterologous substrates, as well as creating docking sites for adapter proteins to bind and nucleate signaling complexes that activate the Ras, PI3 Kinase and PLC pathways. Overexpression of the EGF Receptor is typical in most solid tumors