Osh2 extracts sterols from cortical ERSES. (A) Merged FMs of the indicated strains expressing GFP-D4H and Sec61-mCherry. Arrowheads point to contacts. Individual channels and merged magnified areas are shown. Average ± SEM and t test P values of the cGFP-D4H patch relative fluorescence intensity (RFI) normalized to WT or their number per cell are indicated. Significant differences are shown in red (n > 210 dots and n > 100 cells, respectively). (B) Electron micrographs of WT or osh2Δ cells expressing HA-GFP-D4H, immunodecorated for the HA epitope. cER is in red. Average ± SEM and t test P values of cER diameter and percentage of labeled ER rims or invaginations in WT and osh2Δ cells are indicated. Refer to Fig. S2 A for details. Significant differences are shown in red (n > 300 cER rims and n > 80 invaginations). (C) Time course of cortical GFP-D4H patch RFI, normalized to time 0, in WT or osh2Δ cells mock treated (blue) or treated (red) with the indicated drugs. The drug was added 2 min after initiation of the experiment (red line). t test P values showing significant differences in the last time recorded for the WT are indicated (n ≥ 10). (D) Merged FMs of cells expressing Sec61-CFP, mCherry-D4H, and Osh2-YFP. Individual channels and merged time lapses are shown. (E) Average ± SEM and t test P values of cortical GFP-D4H patch RFI normalized to WT (pOSH2) in osh2Δ cells expressing the empty plasmid (osh2Δ) or plasmids encoding the indicated OSH2 alleles. Significant differences are in red (n > 80 patches).