During autophagy, autophagosomes or autophagic vesicles (AVs) are formed and enclose portions of cytosol and/or entire organelles. Distinct from any other cellular vesicle, AVs have a double membrane, between which lies a very limited lumen. To obtain this peculiar topology, the early AV, the phagophore or isolation membrane (IM) must be either synthesised de novo or expanded by vesicle fusion. In support of the latter, recent work has implicated several different organelles as potential membrane sources during the initial stages of IM formation and expansion. Once closed, AVs use the microtubule network to meet and fuse with several different endocytic organelles on their way to becoming degradative AVs. Recent studies have shed light on the machinery required for both these early and late events to occur.
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