Selective membrane recruitment of EEA1 suggests a role in directional transport of clathrin-coated vesicles to early endosomes
Selective membrane recruitment of EEA1 suggests a role in directional transport of clathrin-coated vesicles to early endosomes
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DOI：
10.1074/jbc.275.6.3745
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发表时间：
2000-02-11
影响因子：
4.8
通讯作者：
Zerial, M
中科院分区：
文献类型：
--
作者：
Rubino, M;Miaczynska, M;Zerial, M
确保转运囊泡和靶细胞器之间的内吞膜运输的方向性的分子机制仍然很差的特点。我们一直在研究的功能，小GTTRab 5在早期内吞运输。体外研究已经证明Rab 5在两种膜融合事件中的作用：质膜衍生的网格蛋白包被囊泡（CCV）和早期内体之间的异型融合以及早期内体之间的同型融合。在同型内体融合中需要几种Rab 5效应物，包括介导内体膜对接的EEA 1、Rabaptin-5、Rabex-5复合物和磷脂酰肌醇3-激酶hVPS 34。在这项研究中，我们研究了Rab 5的定位和功能及其效应在异型融合体外。我们报告说，活性Rab 5的存在是必要的CCV和早期内涵体的异型融合事件发生。这个过程除了Rabaptin-5复合物之外还需要EEA 1。然而，Rab 5和Rabaptin-5在CCV和早期内体之间对称分布，而EEA 1选择性地募集到早期内体的膜上。我们的研究结果表明，EEA 1是一个拴系分子，提供方向性囊泡运输从质膜到早期内体。
The molecular mechanisms ensuring directionality of endocytic membrane trafficking between transport vesicles and target organelles still remain poorly characterized. We have been investigating the function of the small GTPase Rab5 in early endocytic transport. In vitro studies have demonstrated a role of Rab5 in two membrane fusion events: the heterotypic fusion between plasma membrane-derived clathrin-coated vesicles (CCVs) and early endosomes and in the homotypic fusion between early endosomes. Several Rab5 effecters are required in homotypic endosome fusion, including EEA1, which mediates endosome membrane docking, a's well as Rabaptin-5.Rabex-5 complex and phosphatidylinositol 3-kinase hVPS34. In this study we have examined the localization and function of Rab5 and its effecters in heterotypic fusion in vitro. We report that the presence of active Rab5 is necessary on both CCVs and early endosomes for a heterotypic fusion event to occur. This process requires EEA1 in addition to the Rabaptin-5 complex. However, whereas Rab5 and Rabaptin-5 are symmetrically distributed between CCVs and early endosomes, EEA1 is recruited selectively onto the membrane of early endosomes. Our results suggest that EEA1 is a tethering molecule that provides directionality to vesicular transport from the plasma membrane to the early endosomes.