Subsets of epidermal growth factor receptors during activation and endocytosis
Subsets of epidermal growth factor receptors during activation and endocytosis
复制标题
DOI：
10.1074/jbc.272.7.4079
复制
发表时间：
1997-02-14
影响因子：
4.8
通讯作者：
Wong, AJ
中科院分区：
文献类型：
--
作者：
Emlet, DR;Moscatello, DK;Wong, AJ
受体蛋白酪氨酸激酶自磷酸化位点的突变改变了配体依赖性内化和下调，表明这些位点在受体加工中起关键作用。目前，基于个体自磷酸化位点的受体加工没有差异被定义。通过使用含有磷脂酶c - γ(1)的2个同源结构域的谷胱甘肽s -转移酶融合蛋白特异性识别EGF受体(Tyr（P)(992)）上的酪氨酸992，我们发现了这一受体亚群的差异。在EGF刺激后，Tyr(P)（992）受体的数量比识别活化EGF受体的抗体（α - act）识别的受体增加了2倍。EGFR)在A431细胞中。共聚焦荧光显微镜显示，Tyr(P)（992）受体的内吞作用速度较慢，在核旁体中不能迅速集中。与普通人群相比，Tyr(P)（992）受体与更多的SOS、Ras-GTPase激活蛋白、磷脂酰肌醇3-激酶和SHPTP2/syp相关，但与较少的Grb2相关，并且这些受体的磷酸化程度高于普通人群的活性受体。这些发现表明，自磷酸化状态与单个EGF受体的内吞作用、降解和效应分子相互作用有关。基于磷酸化状态的进一步研究将为受体蛋白-酪氨酸激酶信号传导如何被调节提供新的见解。
Mutation of the autophosphorylation sites of receptor protein-tyrosine kinases alters ligand dependent internalization and down-regulation, indicating a critical role for these sites in receptor processing. Currently, no differences in receptor processing based on an individual autophosphorylation site have been defined. By using a glutathione S-transferase fusion protein containing the are homology 2 domains of phospholipase C-gamma(1) to specifically recognize tyrosine 992 on the EGF receptor (Tyr(P)(992)), we have found differences in this subpopulation of receptors. Following EGF stimulation, the number of Tyr(P)(992) receptors increased 2-fold over receptors identified by an antibody that recognizes activated EGF receptors (alpha-Act. EGFR) in A431 cells. Confocal fluorescence microscopy showed that Tyr(P)(992) receptors underwent endocytosis at a slower rate and did not rapidly concentrate in juxtanuclear bodies. Tyr(P)(992) receptors were associated with more SOS, Ras-GTPase activating protein, phosphatidylinositol 3-kinase, and SHPTP2/syp, but less Grb2, than receptors in the general population, and these receptors were more heavily phosphorylated than the general population of active receptors. These findings suggest that autophosphorylation status is relevant to the endocytosis, degradation, and effector molecule interaction of individual EGF receptors. Further investigations based on phosphorylation status should provide new insights into how receptor protein-tyrosine kinase signaling is regulated.