Involved in cytoplasm to vacuole transport (Cvt) and autophagic vesicle formation. Autophagy is essential for maintenance of amino acid levels and protein synthesis under nitrogen starvation. Required for selective autophagic degradation of the nucleus (nucleophagy). Also required for mitophagy, which eliminates defective or superfluous mitochondria in order to fulfill cellular energy requirements and prevent excess ROS production. Conjugation with ATG12, through a ubiquitin-like conjugating system involving ATG7 as an E1-like activating enzyme and ATG10 as an E2-like conjugating enzyme, is essential for its function. The ATG12-ATG5 conjugate acts as an E3-like enzyme which is required for lipidation of ATG8 and ATG8 association to the vesicle membranes (By similarity). Conjugated with ATG12. Conjugated to ATG12; which is essential for autophagy. Belongs to the ATG5 family.