Skip to main content
. Author manuscript; available in PMC: 2020 Apr 2.
Published in final edited form as: Cell Metab. 2019 Apr 2;29(4):803–826. doi: 10.1016/j.cmet.2019.03.003

Figure 1: The molecular machinery of macroautophagy:

Figure 1:

The hallmark of macroautophagy is the double membrane autophagosome that forms by the de novo assembly of membrane from various sources. The process begins with the formation of the phagophore, a process initiated by the ULK1 and VPS34 complexes. Expansion of the phagophore occurs via the continued recruitment of membrane vesicles by ATG9 as well as the conjugation of LC3 to the phagophore membrane (to form LC3-II). LC3 conjugation involves a two-step ubiquitin-like conjugation pathway involving ATG7, ATG10, ATG3, ATG12, ATG5 and ATG16 (refer to text for details). The phagophore expands around the cargo, finally closing to form a cargo-containing autophagosome. The autophagosome subsequently fuses with lysosome(s) by the concerted action of Rab and SNARE proteins to form the autolysosome. Lysosomal hydrolases degrade the inner autophagosomal membrane and the enclosed cargo. The breakdown products, simple macromolecules such as amino acids, are subsequently transported out in the cytoplasm by lysosomal transporters for reuse.