Membrane fusion is a fundamental biochemical reaction and the final step in all vesicular trafficking events. It is crucial for the transfer of proteins and lipids between different compartments and for exo- and endocytic traffic of signaling molecules and receptors. It leads to the reconstruction of organelles such as the Golgi or the nuclear envelope, which decay into fragments during mitosis. Hence, controlled membrane fusion reactions are indispensible for the compartmental organization of eukaryotic cells; for their communication with the environment via hormones, neurotransmitters, growth factors, and receptors; and for the integration of cells into multicellular organisms. Intracellular pathogenic bacteria, such as Mycobacteria or Salmonellae, have developed means to control fusion reactions in their host cells. They persist in phagosomes whose fusion with lysosomes they actively suppress-a means to ensure survival inside host cells. The past decade has witnessed rapid progress in the elucidation of parts of the molecular machinery involved in these membrane fusion reactions. Whereas some elements of the fusion apparatus are remarkably similar in several compartments, there is an equally striking divergence of others. The purpose of this review is to highlight common features of different fusion reactions and the concepts that emerged from them but also to stress the differences and challenge parts of the current hypotheses. This review covers only the endoplasmic fusion reactions mentioned above, i.e., reactions initiated by contacts of membranes with their cytoplasmic faces. Ectoplasmic fusion events, which depend on an initial contact of the fusion partners via the membrane surfaces exposed to the surrounding medium are not discussed, nor are topics such as the entry of enveloped viruses, formation of syncytia, gamete fusion, or vesicle scission (a fusion reaction that leads to the fission of, e.g., transport vesicles).

中文翻译：

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真核细胞中的膜融合。

膜融合是基本的生化反应，是所有囊泡运输事件的最后一步。对于蛋白质和脂质在不同区室之间的转移以及信号分子和受体的胞外和胞吞运输至关重要。它导致细胞器（例如高尔基体或核膜）的重建，这些细胞器在有丝分裂期间会分解成碎片。因此，受控的膜融合反应对于真核细胞的区室组织是必不可少的。通过激素，神经递质，生长因子和受体与环境进行交流；以及将细胞整合到多细胞生物中。细胞内致病细菌，例如分枝杆菌或沙门氏菌，已经开发出控制其宿主细胞中融合反应的方法。它们保留在吞噬体中，吞噬体与溶酶体融合并被其积极抑制，这是确保宿主细胞内存活的一种手段。在过去的十年中，在阐明与这些膜融合反应有关的部分分子机器方面取得了迅速的进展。尽管融合装置的某些元件在几个隔室中非常相似，但其他隔室的差异同样显着。这篇综述的目的是强调不同融合反应的共同特征以及由此产生的概念，同时强调差异和挑战当前假设的某些部分。该综述仅涵盖上述内质融合反应，即由膜与其细胞质表面接触引发的反应。胞质融合事件