Figure.

The Atg-conjugation system is critical for the closure and the inward membrane fission of autophagosomes. This is a schematic representation of autophagosome formation and maturation in cells lacking the Atg-conjugation system. In Atg3 KO MEF cells, the success of autophagosome formation is impaired (the success rate is 30%) and complete closure of autophagosomes and degradation of the IAM are severely delayed. Although the efficiency and the speed are compromised, autophagosomes/autolysosomes are formed in Atg3 KO MEF cells through alternative mechanisms. The brown color indicates lysosomal acid hydrolase.