Mutations in the R-E-D motif impair DNA-dependant TFIIH ATPase activity. (A) 50, 100, and 150 ng of TFIIH(WT), TFIIH/XPB(E253A), XPB(K346R), XPB(E473A) or XPB(Δ516–526) were tested in an ATPase assay in the presence of 200 ng of double-strand circular DNA (Coin et al, 2007). The average percentage±s.d. of phosphate released (Pi/(ATP+Pi)) from three independent experiments is represented in the graph. (B) 50 and 150 ng of TFIIH(WT), TFIIH/XPB(K346R) or TFIIH/XPB(E473A) were tested in an ATPase assay without (lanes 1–6) or with (lanes 7–12) 200 ng of double-strand circular DNA. The average percentage±s.d. of phosphate released (Pi/(ATP+Pi)) from three independent experiments is represented in the graph.