Deletion mapping of potential repression/activation domains in a) p68 and b) p72 as observed in CAT assays using the TK-CAT promoter-reporter plasmid. The pcDNA3-GAL4 expression vector (pcG4) and full-length GAL4-tagged p68/p72 were used as controls. All p68/72 deletion derivatives were expressed as GAL4-tagged fusion proteins in pcG4 and included the amino acids indicated. Additional proteins tested in this assay included the ATPase/helicase GAL4-tagged inactive mutants of p68/p72 (p68N/p72N) and the alternative upstream initiation product of the p72 gene (p82). The amounts of DNA used in the transfections were; TK-CAT- 2.5 μg; pcG4 and all p68/p72 constructs- 1 μg. The % conversion of 14C-labelled chloramphenicol to acetylated forms is shown as an average of five independent experiments. c) Diagram correlating the deletion end-points to the position of the motifs conserved in the DEAD box family of proteins.