Involved in autophagic vesicle formation (By similarity). Conjugation with lgg-3/ATG12, through a ubiquitin-like conjugating system involving atg-7 as an E1-like activating enzyme and atg-10 as an E2-like conjugating enzyme, is essential for its function (By similarity). Most likely a component of an atg-5-lgg-3-atg-16 complex that promotes autophagosome formation by associating with lgg-2, but not lgg-1, at the preautophagosomal membrane (PubMed:24185444). Probably, as part of an atg-5-lgg-3-atg-16 complex, required for lgg-1 lipidation; the complex acts as an E3-like enzyme promoting atg-3-mediated lgg-1 lipidation (Probable). Furthermore, association with atg-16.2 is required for the nucleation of lgg-1 positive autophagic vesicles (PubMed:24185444). Most likely a component of a complex at least containing atg-5, lgg-3/ATG12, atg-16.1 and/or atg-16.2 (Probable). Interacts with lgg-3/ATG12 (By similarity). Interacts with atg-16.1 (via N-terminus) and atg-16.2 (via N-terminus) (PubMed:24185444). Conjugated to lgg-3/ATG12; which is essential for autophagy. Belongs to the ATG5 family.