Fig. 3

Autophagolysosome formation and maturation. Autophagy involves the formation of an isolation membrane. This membrane undergoes elongation, forming a phagophore and a portion of the cytoplasm is separated to form an autophagosome. This involves the ULK1-ATG13-FIP200, Beclin1-PI3K CIII and Atg5-Atg12-Atg16 complexes The autophagosome fuses with a lysosome to form an autophagolysosome, allowing digestive enzymes to degrade any material in the vesicle. TBK1 binds and phosphorylates autophagy receptors OPTN and p62; they bind to ubiquitin residues on target cargo and to LC3-II. This enhances the ability of the receptors to bind ubiquitinated residues on target cargo and LC3-II. This all allows ubiquitinated cargo to be recruited to the phagophore for degradation; the receptors act as adaptors that link cargo to autophagic machinery