Origin of the Autophagosome Membrane in Mammals

Table 2

The source of autophagosome membrane.

Origin	Parts of probable	Induction condition	Different stages of autophagosomes	Contribution
Mitochondria	outer mitochondrial membrane [32]	serum, or serum and amino acid deprivation [32]	phagophore expansion	the isolation membrane (also called the phagophore) expansion [1]
Endoplasmic reticulum	the rough endoplasmic reticulum [33], subdomain of the ER termed the omegasome	amino acid starvation [34], fasted animals	early stages of autophagosome formation [35]	phagophore expansion, elongation of isolation membranes [36]
Golgi	trans-Golgi network,TGN	nitrogen starvation or fasted animals	early stages of autophagosome formation [37]	phagophore formation [38] and expansion, maturation of autophagosomes [39]
Plasma membrane	ATG16L vesicle, lipids of the plasma membrane	amino acid and serum starvation, or nitrogen starvation[40]	early stages of autophagosome formation [41]	the formation of early autophagic precursors [42]
ER–mitochondria contact site	the mitochondria-associated ER membrane (MAM)	rapamycin and Torin 1 [43]	uncertain	phagophore expansion
ERGIC	ERGIC-enriched membrane	nutrient starvation [43]	generate an early autophagosomal membrane precursor [44]	trigger phagophore formation
Recycling endosomes	membrane lipids	nutrient starvation or rich medium	early stages of autophagosome formation	supply membrane lipids for autophagosome formation