The exocyst is an evolutionarily conserved octameric protein complex that mediates the tethering of post-Golgi secretory vesicles to the plasma membrane during exocytosis and is implicated in many cellular processes such as cell polarization, cytokinesis, ciliogenesis and tumor invasion. Using cryo-EM and chemical cross-linking MS (CXMS), we solved the structure of the Saccharomyces cerevisiae exocyst complex at an average resolution of 4.4 Å. Our model revealed the architecture of the exocyst and led to the identification of the helical bundles that mediate the assembly of the complex at its core. Sequence analysis suggests that these regions are evolutionarily conserved across eukaryotic systems. Additional cell biological data suggest a mechanism for exocyst assembly that leads to vesicle tethering at the plasma membrane.

中文翻译：

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胞外复合物的低温-EM结构。

外囊是进化上保守的八聚体蛋白复合物，其在胞吐过程中介导高尔基体后分泌小泡束缚于质膜，并牵涉许多细胞过程，例如细胞极化，胞质分裂，纤毛发生和肿瘤侵袭。使用cryo-EM和化学交联MS（CXMS），我们以4.4Å的平均分辨率解析了酿酒酵母囊外复合物的结构。我们的模型揭示了囊外的结构，并导致确定了介导复合物核心组装的螺旋束。序列分析表明，这些区域在整个真核系统中在进化上是保守的。额外的细胞生物学数据提示了囊外组装的机制，该机制导致质膜上的囊泡束缚。