摘要：

A crucial step in the trafficking of intracellular membranes is membrane fusion. Endocytotic vesicles or phagosomes form via fusion of the apposed exoplasmic leaflets of the invaginated plasma membrane. The endocytotic vesicles are then thought to fuse with endosomes. Later in the endocytotic pathway, endosomes and phagosomes eventually fuse with lysosomes, in a process involving the interaction and fusion of the cytoplasmic leaflets of their membranes. Following endocytosis, receptor-containing vesicles undergo a "fission" or "budding" process to facilitate the transport of receptors back to the plasma membrane. This budding involves the interaction and fusion of the membrane leaflets facing the lumen of the flaccid vesicle. Likewise, in the Golgi apparatus, transport vesicles are thought to bud off from one compartment and fuse with the next one along the cis, medial and trans regions of the organelle.

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