Autophagy-related dual specificity E1 family member; non-canonical ubiquitin-activating enzyme (E1) that mediates the attachment of Atg12p to Atg5p and phosphatidylethanolamine to Atg8p, both required steps in autophagosome formation; intrinsically disordered region of Atg12p negatively regulates Atg7p thioesterification and autophagy, while Atg10p enhances conjugation; involved in methionine restriction extension of chronological lifespan in an autophagy-dependent manner