Sec24C/D-isoform-specific sorting of the preassembled ER-Golgi Q-SNARE complex.
Sec24C/D-isoform-specific sorting of the preassembled ER-Golgi Q-SNARE complex.
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DOI：
10.1091/mbc.e16-04-0229
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发表时间：
2016-09-01
影响因子：
3.3
通讯作者：
Wieland FT
中科院分区：
文献类型：
--
作者：
Adolf F;Rhiel M;Reckmann I;Wieland FT
SNAREs通过与Sec24的直接相互作用被并入COPII囊泡中。在哺乳动物中，Sec24亚型募集Sec22b或由Syntaxin5、GS27和Bet1组成的Q-SNARE复合体。免疫分离的COPII囊泡和Sec24亚型的细胞内定位分析表明，所有er -高尔基SNAREs都存在于相同的囊泡上。分泌蛋白从COPII囊泡的内质网输出。SNARE蛋白是膜融合的核心机制，通过与Sec24的直接相互作用被纳入COPII囊泡。在这里，我们报道了一种将er -高尔基Q-SNAREs分选到COPII囊泡中的新机制。不同的哺乳动物Sec24亚型募集R-SNARE Sec22b或q - snare Syntaxin5、GS27和Bet1。Syntaxin5是唯一一个直接与Sec24C相互作用的Q-SNARE，需要其“开放”构象。Sec24C的IxM货物结合位点的突变导致所有三个Q-SNAREs在COPII囊泡中的分选急剧减少，这意味着它们作为预组装复合物输出内质网。免疫分离的COPII囊泡和Sec24亚型的细胞内定位分析表明，所有er -高尔基SNAREs都存在于同一囊泡上。结合现有数据，我们的研究结果产生了Sec24亚型如何招募融合性SNARE亚基以保持它们在功能上的分离，从而为哺乳动物COPII囊泡提供同源融合的一般概念。
SNAREs are incorporated into COPII vesicles by direct interaction with Sec24. In mammals, Sec24 isoforms recruit either Sec22b or the Q-SNARE complex comprising Syntaxin5, GS27, and Bet1. Analysis of immunoisolated COPII vesicles and intracellular localization of Sec24 isoforms indicates that all ER-Golgi SNAREs are present on the same vesicles. Secretory proteins are exported from the endoplasmic reticulum in COPII vesicles. SNARE proteins—core machinery for membrane fusion—are incorporated into COPII vesicles by direct interaction with Sec24. Here we report a novel mechanism for sorting of the ER–Golgi Q-SNAREs into COPII vesicles. Different mammalian Sec24 isoforms recruit either the R-SNARE Sec22b or the Q-SNAREs Syntaxin5, GS27, and Bet1. Syntaxin5 is the only Q-SNARE that directly interacts with Sec24C, requiring its “open” conformation. Mutation within the IxM cargo-binding site of Sec24C led to a drastic reduction in sorting of all three Q-SNAREs into COPII vesicles, implying their ER export as a preassembled complex. Analysis of immunoisolated COPII vesicles and intracellular localization of Sec24 isoforms indicate that all ER–Golgi SNAREs are present on the same vesicle. Combined with existing data, our findings yield a general concept of how Sec24 isoforms can recruit fusogenic SNARE subunits to keep them functionally apart and thus prime mammalian COPII vesicles for homotypic fusion.