Saccharomyces cerevisiae is one of the best model organisms for the study of endocytic membrane trafficking. While studies in mammalian cells have characterized the temporal and morphological features of the endocytic pathway, studies in budding yeast have led the way in the analysis of the endosomal trafficking machinery components and their functions. Eukaryotic endomembrane systems were thought to be highly conserved from yeast to mammals, with the fusion of plasma membrane-derived vesicles to the early or recycling endosome being a common feature. Upon endosome maturation, cargos are then sorted for reuse or degraded via the endo-lysosomal (endo-vacuolar in yeast) pathway. However, recent studies have shown that budding yeast has a minimal endomembrane system that is fundamentally different from that of mammalian cells, with plasma membrane-derived vesicles fusing directly to a trans-Golgi compartment which acts as an early endosome. Thus, the Golgi, rather than the endosome, acts as the primary acceptor of endocytic vesicles, sorting cargo to pre-vacuolar endosomes for degradation. The field must now integrate these new findings into a broader understanding of the endomembrane system across eukaryotes. This article synthesizes what we know about the machinery mediating endocytic membrane fusion with this new model for yeast endomembrane function.

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酵母最小内膜系统 SNARE 功能的新视角

酿酒酵母是研究内吞膜运输的最佳模式生物之一。虽然对哺乳动物细胞的研究已经表征了内吞途径的时间和形态特征，但对出芽酵母的研究在分析内体运输机制组件及其功能方面处于领先地位。从酵母到哺乳动物，真核内膜系统被认为是高度保守的，质膜衍生的囊泡与早期或循环内体的融合是一个共同特征。内体成熟后，货物会被分类以供重复使用或通过内溶酶体（酵母中的内液泡）途径降解。然而，最近的研究表明，芽殖酵母具有最小的内膜系统，与哺乳动物细胞的内膜系统有着根本的不同，质膜衍生的囊泡直接融合到作为早期内体的反式高尔基体室。因此，高尔基体而不是内体充当内吞囊泡的主要受体，将货物分拣到前液泡内体进行降解。该领域现在必须将这些新发现整合到对真核生物内膜系统的更广泛理解中。本文综合了我们对酵母内膜功能新模型介导内吞膜融合的机制的了解。该领域现在必须将这些新发现整合到对真核生物内膜系统的更广泛理解中。本文综合了我们对酵母内膜功能新模型介导内吞膜融合的机制的了解。该领域现在必须将这些新发现整合到对真核生物内膜系统的更广泛理解中。本文综合了我们对酵母内膜功能新模型介导内吞膜融合的机制的了解。