(A) Schematic representation of the reporter plasmid and expression vectors. The pG5 luc reporter plasmid contains five GAL4-binding sites upstream of the luciferase gene. The GAL4 recognition sites are indicated with solid bars, the TATA box is represented by a shaded box, and the luciferase gene by a solid box. The expression vectors driving the production of GAL4 or GAL4–GAPDH are also presented. The positions of the first and last amino acids of the GAPDH construct are indicated below the construct. (B) Transactivation by GAPDH. COS-7 cells were co-transfected with 0.1 μg of pG5 luc reporter plasmid and 0, 0.1, 0.3 or 0.5 μg of GAL4–GAPDH (bars 1–4). For all reactions the total amount of transfected pGAL4–GAPDH DNA was adjusted to 0.5 μg with empty vector, pGAL4. After 48 h the cells were harvested and luciferase assays were performed. The experiments were repeated three times, and the average of two independent experiments is presented and the error bars are shown.