Figure 1.

The general process of macroautophagy, microautophagy, and chaperone-mediated autophagy. In the process of macroautophagy, the contents are encapsulated by a bilayer membrane structure to form autophagosomes. Autophagosomes then fuse with lysosomes to form autolysosomes, in which the separated contents are usually degraded for recycling. Microautophagy refers to the direct invagination of lysosomal membrane, which then encapsulates cell contents. In the process of chaperone mediated autophagy, the cytoplasmic proteins are transported to lysosomal chambers after binding with chaperones, and then digested by lysosomal enzymes.