Table 2.

Cellular Degradation Processes

Degradation process	Location	Enzymes involved	Targets
Cytosolic proteolysis	Cytosol	Calpains, proteasomes	Cytosolic proteins (mainly short-lived)
Mitochondrial proteolysis	Mitochondria	Lon, Clp-like, and AAA proteases	Mitochondrial proteins
Autophagy (macroautophagy, microautophagy, and chaperone-mediated autophagy)	Lysosomes	Acid hydrolases	All cytosolic macromolecules and organelles
Programmed cell death (PCD)	Whole cell	Effector caspases, lysosomal cathepsins, and endonucleases in PCD-I (classic apoptosis); acid hydrolases in PCD-II (autophagic cell death) and PCD-III (programmed necrosis)	All cellular components