Figure 1.

The autophagic process of three different forms in mammalians. (1) Macroautophagy, which is characterized by the formation of autophagosomes with a double-layer membrane structure engulfs intracellular macromolecular substances in a wrapped manner, and the autophagosome eventually fuses with lysosome to form autophagic lysosome, and the inclusion bodies are degraded by hydrolytic enzymes in lysosome. (2) Microautophagy, which is characterized by the specific organelles are directly engulfed in an invaginated manner by the deformation of lysosomal or vacuole surface, and the lysosomal membrane inwardly folds to crush the contents. (3) Chaperone-mediated autophagy (CMA), which is characterized by the specific amino acid sequence (such as KEFRQ motif) of soluble protein is identified and combined by a chaperone-dependent protein (such as HSPA8 complex), and transfer it to lysosomes via the receptor LAMP2A on the lysosomal membrane, so as to allow misfolded proteins to undergo defolding and complete degradation by hydrolytic enzymes in lysosome.