FIGURE 7.

Multiple stresses induce assembly of the Elongin A ubiquitin ligase. A, FRET efficiencies in U2OS cells expressing Halo-Elongin A and mCherry-CUL5. AP-FRET was measured in control cells or 5 min after microirradiation or after treatment for the indicated times with camptothecin, α-amanitin, DRB, or triptolide, with or without KU60019 added 1 h prior to the addition of drugs or microirradiation. Data for cells treated with camptothecin without KU60019 are from the same cells as in Fig. 4D and are included for comparison. Values represent average ± S.E. (error bars) (n ≥ 18). B, kinetics of recruitment of Halo-Elongin A after microirradiation of U2OS cells (n ≥ 10) treated or not with KU60019; data were analyzed as in Fig. 5C. The insets show representative images taken 60 s after microirradiation. Arrows, regions of microirradiation. C, AP-FRET was measured in U2OS cells after 12, 4, or 1 h of treatment with histidinol (HisOH), thapsigargin (Tg), or retinoic acid (RA), respectively, with or without KU60019. In each case, Hoechst dye was added to cultures 1 h before the addition of compound or vehicle. Values represent average ± S.E. (n = 10).