Mammalian GGAs act together to sort mannose 6-phosphate receptors.
Mammalian GGAs act together to sort mannose 6-phosphate receptors.
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DOI：
10.1083/jcb.200308038
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发表时间：
2003-11-24
影响因子：
7.8
通讯作者：
Kornfeld, Stuart
中科院分区：
文献类型：
--
作者：
Ghosh, Pradipta;Griffith, Janice;Geuze, Hans J;Kornfeld, Stuart
GGA（Golgi-localized，γ ear-containing，ADP ribosylation factor-binding proteins）是一类参与高尔基体和内体之间蛋白质运输的多结构域蛋白。我们研究了这三种哺乳动物GGA是否独立或共同发挥作用来介导它们的功能。使用冷冻免疫金电子显微镜，三个GGA共定位在包被芽和泡在trans-Golgi网络（TGN）的HeLa细胞。在体外结合实验中发现的GGA之间的多域相互作用，和化学交联实验表明，GGA 1和2形成一个复杂的高尔基体膜。每个GGA的RNA干扰导致其他GGA的水平降低，并从TGN重新分配到胞质溶胶。这与阳离子非依赖性甘露糖6-磷酸受体掺入TGN网格蛋白包被的囊泡受损、受体向内体的部分再分布以及组织蛋白酶D的错误分选有关。TGN的形态也发生了改变。这些发现表明，三种哺乳动物的GGA合作，以分类货物，并需要维持TGN结构。
The GGAs (Golgi-localized, γ ear–containing, ADP ribosylation factor–binding proteins) are multidomain proteins implicated in protein trafficking between the Golgi and endosomes. We examined whether the three mammalian GGAs act independently or together to mediate their functions. Using cryo-immunogold electron microscopy, the three GGAs were shown to colocalize within coated buds and vesicles at the trans-Golgi network (TGN) of HeLa cells. In vitro binding experiments revealed multidomain interactions between the GGAs, and chemical cross-linking experiments demonstrated that GGAs 1 and 2 form a complex on Golgi membranes. RNA interference of each GGA resulted in decreased levels of the other GGAs and their redistribution from the TGN to cytosol. This was associated with impaired incorporation of the cation-independent mannose 6-phosphate receptor into clathrin-coated vesicles at the TGN, partial redistribution of the receptor to endosomes, and missorting of cathepsin D. The morphology of the TGN was also altered. These findings indicate that the three mammalian GGAs cooperate to sort cargo and are required for maintenance of TGN structure.