Figure 1.

Three types of autophagy. In the major autophagic pathway, various organelles, including the endoplasmic reticulum (ER), mitochondria, mitochondria-associated membranes (MAMs), the Golgi, the plasma membrane and recycling endosomes could supply membrane sources for nucleation of the isolation membranes (originally termed the phagophore), which eventually develop into autophagosome through elongation. Mature autophagosome fuses with a lysosome to form an autolysosome, in which the cargoes sequestered by the autophagosome is degraded and released into the cytoplasm for use in cellular processes, including protein biosynthesis and energy production.