FIG. 10.

Analysis of mutant SAGA complexes. (A) SAGA has reduced HAT activity in TAF90 mutants. Fractions containing SAGA (fractions 38 to 42 from Fig. 9) were pooled and analyzed by Western blotting and HAT assays using oligonucleosomes as substrates. The relative levels of Gcn5p were determined from appropriately exposed blots using NIH Image software and are expressed as the percentage of the wild-type (WT) level. HAT activity was compared to that of SAGA isolated from wild-type cells, which was set at 100%. (B) Size exclusion chromatography. The pooled SAGA-containing fractions from the Mono Q chromatography (fractions 38 to 42 from Fig. 9) were concentrated by filtration and fractionated on a Superose 6 column. Each fraction was analyzed by Western blotting and HAT assays using nucleosomes as a substrate. The void volume corresponds to fraction 14. No HAT activity or SAGA components were detected in later-eluting fractions, and thus only fractions 15 to 23 are shown.