Effect on Golgi structure of disrupting ERES. (A) Distribution of the early Golgi marker Vig4 before and after anchor-away of the ERES components Sec23 and Shl3. A strain expressed GFP-Vig4 together with the Rpl17-FKBPx4 ribosomal anchor as well as Sec23-FRB and Shl23-FRB. Images were captured before and after treatment with rapamycin (Rapa) for 10 min. Scale bar, 1 µm. (B) Representative thin-section electron micrographs of a strain expressing the Rpl17-FKBPx4 ribosomal anchor as well as Sec23-FRB and Shl23-FRB, showing the loss of tightly stacked Golgi structures after ERES were disrupted by treatment with Rapa for 20 min. Some cells displayed structures that resembled Golgi remnants, and others displayed no recognizable Golgi structures. Scale bars, 1 µm (top row) or 200 nm (bottom row). (C) Quantification of the EM data from B. The average number of cisternae in tightly stacked Golgi units was measured for ∼60 individual cell sections in each sample. Bars indicate SEM. As indicated by the asterisks, the average cisterna number in the rapamycin-treated sample was significantly lower at P < 0.0001.