Atg8ylation and its cell biological manifestations including canonical autophagy, noncanonical autophagy, and related nonautophagic processes. (A) Canonical autophagy as a classic output of atg8ylation and the process of double-membrane autophagosome formation with atg8ylation-independent and atg8ylation-dependent stages. ATG8-negative prophagophore (HyPAS) is defined by fusion of FIP200⁺ early-secretory pathway/cis-Golgi–derived membrane with ATG16L1⁺ endosomal membarnes. HyPAS converts to ATG8⁺ (usually referred as LC3⁺) phagophore, which sequesters the cargo and, upon ESCRT-catalyzed membrane closure, fuses with lysosomes leading to cargo degradation. (B and C) Noncanonical autophagy-related processes that do not involve formation of double-membrane autophagosomes and instead rely on atg8ylation of single-membrane organelles induced in response to membrane stress or other signals requiring membrane remodeling. (D) Processes utilizing atg8ylation that do not include canonical or noncanonical autophagy-related processes. Boxes indicate immunological processes associated with particular atg8ylation outputs. Details in the text.