The Intracellular Juxtamembrane Domain of the Epidermal Growth Factor (EGF) Receptor Is Responsible for the Allosteric Regulation of EGF Binding
The Intracellular Juxtamembrane Domain of the Epidermal Growth Factor (EGF) Receptor Is Responsible for the Allosteric Regulation of EGF Binding
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DOI：
10.1074/jbc.m109.001487
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发表时间：
2009-05-15
影响因子：
4.8
通讯作者：
Pike, Linda J.
中科院分区：
文献类型：
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作者：
Macdonald-Obermann, Jennifer L.;Pike, Linda J.
我们先前已经表明，表皮生长因子（EGF）与其受体的结合可以通过涉及聚集系统中的负协同性的模型来最好地描述（Macdonald，J.L.，Pike，L. J.（2008）Proc. Natl. Acad. Sci.联合S. A. 105，112-117）。然而，尽管生物化学分析表明EGF诱导其受体的二聚化，结合数据没有提供EGF结合和二聚体组装之间存在正相关的证据。通过分析结合EGF的受体突变体的数量，我们现在报告说，在幼稚的，未磷酸化的EGF受体，配体结合是积极联系的受体二聚化，但取消后的受体自磷酸化的联系。磷酸化和未磷酸化的EGF受体都表现出负协同性，表明在机械上，协同性与连锁现象不同。尽管如此，在EGF结合中观察到的正向连接和负向协同性都需要细胞内质膜结构域的存在。这表明EGF受体系统中存在由内而外的信号传导。先前已经显示胞内质膜结构域是激活EGF受体酪氨酸激酶所需的（Thiel，K. W.，和Carpenter，G.等人（2007）Proc.Natl. Acad. Sci.联合S. A. 104，19238-19243）。我们的实验扩大了这个域的作用，包括配体结合的细胞外结构域的变构控制。
We have previously shown that the binding of epidermal growth factor (EGF) to its receptor can best be described by a model that involves negative cooperativity in an aggregating system (Macdonald, J. L., and Pike, L. J. (2008) Proc. Natl. Acad. Sci. U. S. A. 105, 112-117). However, despite the fact that biochemical analyses indicate that EGF induces dimerization of its receptor, the binding data provided no evidence for positive linkage between EGF binding and dimer assembly. By analyzing the binding of EGF to a number of receptor mutants, we now report that in naive, unphosphorylated EGF receptors, ligand binding is positively linked to receptor dimerization but the linkage is abolished upon autophosphorylation of the receptor. Both phosphorylated and unphosphorylated EGF receptors exhibit negative cooperativity, indicating that mechanistically, cooperativity is distinct from the phenomenon of linkage. Nonetheless, both the positive linkage and the negative cooperativity observed in EGF binding require the presence of the intracellular juxtamembrane domain. This indicates the existence of inside-out signaling in the EGF receptor system. The intracellular juxtamembrane domain has previously been shown to be required for the activation of the EGF receptor tyrosine kinase (Thiel, K. W., and Carpenter, G. (2007) Proc. Natl. Acad. Sci. U. S. A. 104, 19238-19243). Our experiments expand the role of this domain to include the allosteric control of ligand binding by the extracellular domain.