D. Summary of microscopy analysis of ER-resident proteins co-localization with GFP-Snc1-PEM in cells overexpressing GFP-Snc1-PEM: WT (PEP4PRB1) vs pep4Δ prb1Δ (left), and ypt1-1PEP4PRB1 vs ypt1-1pep4Δ prb1Δ (right). Microscopy and quantification are shown in Fig 7A and 7C and S7 Fig. In YPT1 cells, whereas >60% of Hmg1 and Sec61 (green) co-localize with Snc1-PEM in strains defective in vacuolar proteolysis, Sec12, Sec13 and Kar2 are not changed significantly (blue and grey). Hmg1 and Sec61 (green) co-localize with Snc1-PEM in >70% of ypt1-1 and >80% of ypt1-1pep4Δ prb1Δ mutant cells, whereas Sec13 and Kar2 (blue and grey) do so in <15% of the cells. The level of Sec12 co-localization with Snc1-PEM is intermediate, ~38% in ypt1-1 and ypt1-1pep4Δ prb1Δ. Error bars represent STDEV. Results in panels A and B represent at least two independent experiments. 