Epidermal growth factor receptor juxtamembrane region regulates allosteric tyrosine kinase activation
Epidermal growth factor receptor juxtamembrane region regulates allosteric tyrosine kinase activation
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DOI：
10.1073/pnas.0703854104
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发表时间：
2007-12-04
影响因子：
11.1
通讯作者：
Carpenter, Graham
中科院分区：
文献类型：
--
作者：
Thiel, Kristina W.;Carpenter, Graham
表皮生长因子受体（ErbB-1）的胞外和酪氨酸激酶结构域的结构研究提供了相当多的了解方面的受体激活机制，但ErbB-1的其他区域的贡献尚未确定。这项研究表明，细胞内的质膜（JM）区域在激酶激活机制中起着至关重要的作用。在本文所述的实验中，整个ErbB-1胞内结构域（ICD）已在哺乳动物细胞中表达，以探索JM区在激酶活性中的意义。JM区（Delta JM）的缺失导致ICD酪氨酸磷酸化的严重损失，表明该区域是酪氨酸激酶结构域最大活性所必需的。Delta JM和二聚化缺陷激酶结构域ICD突变体的共表达揭示了JM区域对于二聚体内的变构激酶活化和生产性单体相互作用是不可或缺的。对完整受体的研究证实了JM区在激酶活化中的作用。在JM区域内，Thr-654是已知的蛋白激酶C（PKC）磷酸化位点，其在完整的ErbB-1受体的背景下调节激酶活性;然而，机制尚不清楚。而T654 A突变促进增加ICD酪氨酸磷酸化，磷酸模拟T654 D突变体产生ICD酪氨酸磷酸化减少50%。类似于Delta JM突变体，T654 D突变ICD未能与野生型单体相互作用。这项研究揭示了ErbB-1的细胞内JM区域在变构激酶激活中的不可或缺的作用。
Structural studies of the extracellular and tyrosine kinase domains of the epidermal growth factor receptor (ErbB-1) provide considerable insight into facets of the receptor activation mechanism, but the contributions of other regions of ErbB-1 have not been ascertained. This study demonstrates that the intracellular juxtamembrane (JM) region plays a vital role in the kinase activation mechanism. In the experiments described herein, the entire ErbB-1 intracellular domain (ICD) has been expressed in mammalian cells to explore the significance of the JM region in kinase activity. Deletion of the JM region (Delta JM) results in a severe loss of ICD tyrosine phosphorylation, indicating that this region is required for maximal activity of the tyrosine kinase domain. Coexpression of Delta JM and dimerization-deficient kinase domain ICD mutants revealed that the JM region is indispensable for allosteric kinase activation and productive monomer interactions within a dimer. Studies with the intact receptor confirmed the role of the JM region in kinase activation. Within the JM region, Thr-654 is a known protein kinase C (PKC) phosphorylation site that modulates kinase activity in the context of the intact ErbB-1 receptor; yet, the mechanism is not known. Whereas a T654A mutation promotes increased ICD tyrosine phosphorylation, the phosphomimetic T654D mutant generates a 50% reduction in ICD tyrosine phosphorylation. Similar to the Delta JM mutants, the T654D mutant ICD failed to interact with a wild-type monomer. This study reveals an integral role for the intracellular JM region of ErbB-1 in allosteric kinase activation.