Required for cytoplasm to vacuole transport (Cvt) vesicle formation and efficient autophagy. Plays a role in ATG protein retrieval from the pre-autophagosomal structure (PAS) and is especially required for autophagy-dependent cycling of ATG9. Also plays a role in regulation of filamentous growth (By similarity). Forms a complex with ATG9 and ATG27. Found in pre-autophagosomal structure and other punctate structures. Correct localization of ATG23 to the membranes is strictly dependent of ATG9. Cycling through the pre-autophagosomal structure and correct location to other punctate structures is ATG1- and ATG13-dependent (By similarity). Belongs to the ATG23 family.