Phospholipid scramblase involved in autophagy and cytoplasm to vacuole transport (Cvt) vesicle formation. Cycles between the preautophagosomal structure/phagophore assembly site (PAS) and the cytoplasmic vesicle pool and supplies membrane for the growing autophagosome. Lipid scramblase activity plays a key role in preautophagosomal structure/phagophore assembly by distributing the phospholipids that arrive through ATG2 from the cytoplasmic to the luminal leaflet of the bilayer, thereby driving autophagosomal membrane expansion. Required for mitophagy. Also involved in endoplasmic reticulum-specific autophagic process and is essential for the survival of cells subjected to severe ER stress. Different machineries are required for anterograde trafficking to the PAS during either the Cvt pathway or bulk autophagy and for retrograde trafficking