FIGURE 2: Up-regulation of Osh6 traps PI4P on the Golgi. (A) Comparison of the localization of PI4P in wild type (BY4742), sac1Δ, P_ERG6–OSH6 (FTY536), and P_ERG6–OSH7 (FTY521). The indicated strains were transformed with the 2XPH-OSBP-GFP plasmid, grown to early log phase and photographed. The arrowhead points to a cell with PI4P on the PM in addition to intracellular punctate. The arrow points to a cell with PI4P-decorated circular organelles in sac1Δ. (B) Distribution of cells with different PI4P intensities. The intensity of PI4P of each cell was measured by the ImageJ software. Then cells were grouped based on the relative PI4P intensity with a ten arbitrary unit (reported by ImageJ) interval (X-axis). The fraction of each group in the whole set is presented on Y-axis. Sample sizes are 61 for wild type, 64 for sac1Δ, 83 for P_ERG6–OSH6, and 69 for P_ERG6–OSH7. (C) Distribution of cells with bud-enriched PI4P in different strains. A cell was counted as ‘bud enriched' if its bud PI4P signal/(bud signal + mother signal) is larger than 0.6. Sample sizes are 31 for wild type, 34 for sac1Δ and 35 for P_ERG6–OSH6. Fisher exact test shows that sac1Δ is significantly different from wild type (P=0.029) and that P_ERG6–OSH6 is not significantly different from wild type. (D) PI4P colocalized with the trans-Golgi network marker Sec7-mCherry. Cells of the Sec7-mCherry integrated version of P_ERG6–OSH6 (FTY624) and P_ERG6–OSH7 (FTY625) strains were transformed with the 2XPH-OSBP-GFP plasmid. Early log phase cells of the transformants were photographed under FITC or Texas Red filter. Representative images are shown here. Arrow heads point to areas where PI4P overlapped with Sec7mCherry.