Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany.
Structural Studies Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.
Elife. 2017 Nov 17;6:e32493. doi: 10.7554/eLife.32493.
COPI-coated vesicles mediate trafficking within the Golgi apparatus and from the Golgi to the endoplasmic reticulum. The structures of membrane protein coats, including COPI, have been extensively studied with reconstitution systems using purified components. Previously we have determined a complete structural model of the reconstituted COPI coat (Dodonova et al., 2017). Here, we applied cryo-focused ion beam milling, cryo-electron tomography and subtomogram averaging to determine the native structure of the COPI coat within vitrified cells. The native algal structure resembles the mammalian structure, but additionally reveals cargo bound beneath β'-COP. We find that all coat components disassemble simultaneously and relatively rapidly after budding. Structural analysis , maintaining Golgi topology, shows that vesicles change their size, membrane thickness, and cargo content as they progress from to , but the structure of the coat machinery remains constant.
COP 被膜小泡介导高尔基体内部和高尔基体到内质网之间的物质运输。使用纯化组分的重建系统，已经对包括 COPI 在内的膜蛋白被膜结构进行了广泛研究。此前，我们已经确定了重建的 COPI 被膜的完整结构模型（Dodonova 等人，2017 年）。在这里，我们应用冷冻聚焦离子束铣削、冷冻电子断层扫描和亚断层平均法来确定在玻璃化细胞内 COPI 被膜的天然结构。天然藻类结构类似于哺乳动物结构，但此外还揭示了β'-COP 下方结合的货物。我们发现，在出芽后，所有的被膜成分都会同时且相对快速地解组装。结构分析表明，在从到的过程中，囊泡会改变其大小、膜厚度和货物含量，但被膜机械结构保持不变。
