Required for cytoplasm to vacuole transport (Cvt), pexophagy and mitophagy. Also involved in endoplasmic reticulum-specific autophagic process and is essential for the survival of cells subjected to severe ER stress. Functions in protein retrieval from the endocytic pathway (By similarity). The PX domain binds phosphatidylinositol 3-phosphate which is necessary for peripheral membrane localization of ATG20 to the perivacuolar punctate structures. Belongs to the sorting nexin family.