Autophagy is an essential cellular process that maintains homeostasis through the degradation and recycling of cytoplasmic organelles and macromolecules. Substrates targeted for autophagy are engulfed in a double-membrane structure called the autophagosome which is then targeted to the lysosome for degradation. The initiation of autophagy requires two separate ubiquitin-like protein (UBL) systems that regulate autophagosome assembly. In these systems Atg7 acts as an E1-like enzyme for the UBLs Atg12 and Atg8.
