Fig. 6. Crt1 mediates the TAF_II dependence of the RNR genes. (A) Deletion of CRT1 relieves the TAF_II requirement. Strains were treated as described in Figure 5A. (B) TFIID and Crt1 interact in vitro. Yeast whole-cell extracts were chromatographed on GST, GST–Crt1 and GST–VP16 affinity columns. After extensive washing, the bound proteins were eluted with high salt and were detected by western blotting. The relative amounts of material loaded onto the gel are as follows: load, 1/300 of the total; eluate, 1/35 of the total. Note that the amounts of the smaller TAF_IIs (TAF_II47, TAF_II25 and TAF_II17) in the eluates appear lower than they actually are because of the spreading of the signal caused by the high salt in the eluate fractions.