Fig. 2. Effect of GFP-PDS overexpression on ER morphology in COS7 cells. (A) Confocal images of cells co-expressing YFP-PDS and free cytosolic CFP. The ER is vesiculated and CFP (red) is excluded from the lumen of the vesicular membranes (white arrows). (B) Confocal images of cells co-expressing YFP-PDS and ER-luminal helss-CFP. The lumen of the vesicular membrane structures is labeled with helss-CFP, confirming that they are ER membranes. The relative topology and distributions of YFP-PDS (green) and CFP or helss-CFP (red) in each panel are summarized in the scheme on the right side.