() Representative results of BTAF1–TBP interaction assay in solution. Binding reactions were performed as described in Materials and Methods. Lane 5 contained wild-type TBP (50 ng), lanes 6–19 contained indicated mutant TBP proteins (50 ng) and no TBP was added to lane 20. Lanes 5–20 contained 5 µl of BTAF1-enriched lysate. BTAF1 and TBP proteins were co-immunoprecipitated using TBP antibody. Indicated amounts of BTAF1-containing lysate were loaded as the input control (lanes 1–4). Proteins were visualized using specific antibodies. () Human TBP model () showing results of BTAF1–TBP interaction. Top left—view from upstream DNA; top right—view from downstream DNA (start site); bottom left—view on the top (convex) TBP surface; and bottom right—view on the DNA-binding (concave) TBP surface. Residues affected in BTAF1–TBP interaction by mutations in TBP are indicated (, column 2): red,