Stabilizes the ATG5-ATG12 conjugate and mediates the formation of the 350 kDa complex, which is necessary for autophagy. The ATG5-ATG12/ATG16 complex is required for efficient promotion of ATG8-conjugation to phosphatidylethanolamine and ATG8 localization to the pre-autophagosomal structure (PAS). Recruits also ATG3 to the PAS. Involved in endoplasmic reticulum-specific autophagic process and is essential for the survival of cells subjected to severe ER stress. Homodimer. Part of the 350 kDa complex which is at least composed of ATG5, ATG12 and ATG16. Several units of each may be present in this complex. Interacts directly with ATG12. Present with 573 molecules/cell in log phase SD medium. Belongs to the ATG16 family.