Figure 1. Validation of inferred TF activity modulation.

(A) Schematic diagram showing how T-profiler [22] was used to convert each genomewide mRNA expression profile to a set of t-values that quantify the change in regulatory activity for each TF for which a set of putative targets (“regulon”) was available. The results are available at http://bussemakerlab.org/RegulonProfiler/. (B) Change in regulatory activity of the activator Yap1p and the repressor Rox1p when the corresponding factors are deleted or overexpressed, as inferred by T-profiler. The t-values for Yap1p are based on the ChIP-based regulon (rich medium), while for Rox1p a motif-based (YCTATTGTT) regulon was used. As expected, a Yap1p regulon response is observed for wild-type cells stressed using H₂O₂, but not for Δyap1 cells in the same condition. (C) Timing of the activation of the Crz1p motif-based gene set during CaCl₂ [31] and DTT [27] stress. Note that the t-value for each time point is derived from a distinct genomewide expression profile. (D) Cellular localization of Crz1p during CaCl₂ (upper panel) and DTT stress (lower panel) assayed using fluorescence microscopy. We used DAPI staining (data not shown) to confirm that the small bright spots to which GFP-tagged Crz1p has translocated are the nuclei of the cells.