D. Atg9 is present on aberrant ER structures that accumulate in ypt1-1 mutant cells. WT and ypt1-1 mutant cells expressing Atg9-mCherry from the chromosome and GFP-Snc1-PEM from a 2μ plasmid were analyzed by live-cell microscopy. Whereas in WT cells (top), the GFP-Snc1-PEM localizes to the cell membrane and Atg9-mCherry to intracellular puncta, the two proteins co-localize in 100% of the ypt1-1 mutant cells (bottom) that accumulate intracellular GFP-Snc1-PEM structures (~80%). Shown from left to right: DIC, GFP, mCherry, merge, % cells with intracellular Snc1-PEM, and % cells with co-localization (number of cells with observed phenotype / total number of cells analyzed). 