EEA1, a tethering protein of the early sorting endosome, shows a polarized distribution in hippocampal neurons, epithelial cells, and fibroblasts
EEA1, a tethering protein of the early sorting endosome, shows a polarized distribution in hippocampal neurons, epithelial cells, and fibroblasts
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DOI：
10.1091/mbc.11.8.2657
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发表时间：
2000-08-01
影响因子：
3.3
通讯作者：
Parton, RG
中科院分区：
文献类型：
--
作者：
Wilson, JM;de Hoop, M;Parton, RG
EEA 1是一种早期内体Rab 5效应蛋白，在与早期内体融合之前参与进入的内吞囊泡的对接。由于在极化和非极化细胞中存在复杂的内体途径，我们研究了EEA 1在不同细胞类型中的分布。超微结构分析表明，EEA 1是目前的一个子域的早期分选内体，但不是网格蛋白包被的囊泡，在早期内体融合提供方向性的作用一致。此外，EEA 1与从内体结构域的细胞质表面延伸的丝状物质相关，这也与EEA 1的拴系/对接作用一致。在极化细胞（Madin-Darby犬肾细胞和海马神经元）中，EEA 1存在于“基底外侧型”内体隔室的子集上，表明EEA 1调节特定的内吞途径。在上皮细胞和成纤维细胞中，EEA 1和转染的顶端内体标记物内管蛋白标记不同的内体群体。因此，在极化和非极化的哺乳动物细胞中至少存在两组不同的早期内体。EEA 1可以提供特异性和方向性的融合事件发生在一个子集的这些内体在极化和非极化细胞。
EEA1 is an early endosomal Rab5 effector protein that has been implicated in the docking of incoming endocytic vesicles before fusion with early endosomes. Because of the presence of complex endosomal pathways in polarized and nonpolarized cells, we have examined the distribution of EEA1 in diverse cell types. Ultrastructural analysis demonstrates that EEA1 is present on a subdomain of the early sorting endosome but not on clathrin-coated vesicles, consistent with a role in providing directionality to early endosomal fusion. Furthermore, EEA1 is associated with filamentous material that extends from the cytoplasmic surface of the endosomal domain, which is also consistent with a tethering/docking role for EEA1. In polarized cells (Madin-Darby canine kidney cells and hippocampal neurons), EEA1 is present on a subset of "basolateral-type" endosomal compartments, suggesting that EEA1 regulates specific endocytic pathways. In both epithelial cells and fibroblastic cells, EEA1 and a transfected apical endosomal marker, endotubin, label distinct endosomal populations. Hence, there are at least two distinct sets of early endosomes in polarized and nonpolarized mammalian cells. EEA1 could provide specificity and directionality to fusion events occurring in a subset of these endosomes in polarized and nonpolarized cells.