Ubiquitin ligase activity of c-Cbl guides the epidermal growth factor receptor into clathrin-coated pits by two distinct modes of Eps15 recruitment
Ubiquitin ligase activity of c-Cbl guides the epidermal growth factor receptor into clathrin-coated pits by two distinct modes of Eps15 recruitment
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DOI：
10.1074/jbc.m409765200
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发表时间：
2004-12-31
影响因子：
4.8
通讯作者：
Borst, J
中科院分区：
文献类型：
--
作者：
de Melker, AA;van der Horst, G;Borst, J
我们以前已经证明，c-Cbl需要在Eps 15中存在功能性泛素相互作用基序（UIM）来介导表皮生长因子受体（EGFR）的内吞作用。c-Cbl的泛素连接酶活性和Eps 15的UIM对于Eps 15的质膜募集和配体结合的EGFR进入含有Eps 15的包被凹坑和囊泡是必要的。这是一致的情况下，泛素部分附加到激活的EGFR复合物作为对接网站的Eps 15，从而招募受体到网格蛋白包被的坑。在这里，我们已经研究了这一过程所需的c-Cbl的其他结构特征。我们发现c-Cbl可以通过两种不同的机制引导配体结合的EGFR进入Eps 15内化途径。这些依赖于直接结合EGFR的c-Cbl的磷酸酪氨酸结合结构域或环指的C末端区域，其允许间接结合受体上的替代位点。对于泛素修饰的EGFR或Cbl结合泛素化底物CIN 85作为Eps 15的UIM的对接位点，不存在严格的要求。仅在磷酸酪氨酸结合依赖性途径中，EGFR被泛素化，并可作为Eps 15的募集位点。只有在这一途径中，Eps 15被酪氨酸磷酸化，但这似乎与其参与EGFR内化的能力无关。
We have demonstrated previously that c-Cbl requires the presence of a functional ubiquitin interacting motif (UIM) in Eps15 to mediate epidermal growth factor receptor ( EGFR) endocytosis. Both the ubiquitin ligase activity of c-Cbl and the UIM of Eps15 were necessary for plasma membrane recruitment of Eps15 and entry of ligand-bound EGFR into coated pits and vesicles containing Eps15. This is consistent with a scenario in which ubiquitin moieties appended to activated EGFR complexes act as docking sites for Eps15 and thereby recruit receptors into clathrin coated pits. Here, we have investigated which additional structural features of c-Cbl are required for this process. We find that c-Cbl can guide ligand-bound EGFR into the Eps15 internalization route by two distinct mechanisms. These are either dependent on the phosphotyrosine binding domain of c-Cbl that directly binds to the EGFR or on the region C-terminal of the Ring finger, which allows for indirect binding to an alternative site on the receptor. No strict requirement exists for either ubiquitin modified EGFR or the Cbl binding ubiquitination substrate CIN85 as docking site for the UIM of Eps15. Only in the phosphotyrosine binding-dependent pathway, the EGFR is ubiquitinated and may serve as a site of recruitment for Eps15. Only in this pathway, Eps15 is tyrosine-phosphorylated, but this appears unrelated to its capacity to participate in EGFR internalization.