Alteration of the kinetic properties of the epidermal growth factor receptor tyrosine kinase by basic proteins.
Alteration of the kinetic properties of the epidermal growth factor receptor tyrosine kinase by basic proteins.
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碱性蛋白改变表皮生长因子受体酪氨酸激酶的动力学特性。
DOI：
10.1042/bj2810107
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Bertics,PJ
中科院分区：
文献类型：
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作者：
Hubler,L;Leventhal,PS;Bertics,PJ
先前的研究表明，富含赖氨酸和苏氨酸的蛋白质可以增强酪氨酸和丝氨酸/苏氨酸蛋白激酶的活性。然而，这种激活的动力学和机制尚未完全了解。因此，我们研究了聚（氨基酸）和富含精氨酸的蛋白质，鱼精蛋白，改变表皮生长因子（EGF）受体蛋白酪氨酸激酶活性的动力学特性，使用免疫亲和纯化的人表皮样癌（A431）细胞分离的受体的能力。在ATP和肽底物的非饱和剂量下，聚（L-赖氨酸）、聚（L-精氨酸）和鱼精蛋白刺激EGF受体激酶活性3-5倍，而聚（L-谷氨酸）没有影响。初步动力学研究表明，在最大速度的增加和减少的表观Km的肽底物血管紧张素II的存在下的基本效应。通过产物抑制的动力学机制的进一步分析显示，鱼精蛋白改变了ADP对肽底物的抑制模式，但对ATP没有影响。这种变化表明，在鱼精蛋白存在下，受体能够形成酶-血管紧张素II-ADP三元复合物，但在鱼精蛋白不存在下则不能。此外，基本效应物对EGF受体的C-末端截短形式的激酶活性具有显著降低的影响。因此，激酶活性的变化可能部分由受体的C-末端区域介导，该区域含有受体自身磷酸化的位点。这些结果表明，蛋白质的基本结构域可以与EGF受体相互作用，诱导其动力学性质的变化，特别是关于反应物的识别和结合。
Previous studies have shown that lysine- and arginine-rich proteins can enhance the activity of tyrosine and serine/threonine protein kinases. However, the kinetics and mechanism of this activation are not fully understood. Therefore we investigated the ability of poly(amino acids) and the arginine-rich protein, protamine, to alter the kinetic properties of epidermal growth factor (EGF) receptor protein-tyrosine kinase activity using immunoaffinity-purified receptor isolated from human epidermoid carcinoma (A431) cells. Poly(L-lysine), poly(L-arginine) and protamine stimulated EGF receptor kinase activity by 3-5-fold at non-saturating doses of ATP and peptide substrate, while poly(L-glutamate) had no effect. Initial kinetic studies demonstrated an increase in the maximum velocity and a decrease in the apparent Km for the peptide substrate angiotensin II in the presence of the basic effectors. Further analysis of the kinetic mechanism by product inhibition revealed that protamine altered the pattern of ADP inhibition towards the peptide substrate but not towards ATP. The change was indicative of the receptor's ability to form an enzyme-angiotensin II-ADP ternary complex in the presence of protamine but not in its absence. In addition, the basic effectors had a substantially decreased influence on the kinase activity of a C-terminally truncated form of the EGF receptor. Thus the changes in kinase activity may be partially mediated by the C-terminal region of the receptor, which contains the sites of receptor self-phosphorylation. These results suggest that the basic domains of proteins can interact with the EGF receptor to induce changes in its kinetic properties, especially with regard to reactant recognition and binding.