FIG. 5.

PARP has transcriptional repression activity. The pM-PARP eukaryotic expression construct encoding a Gal4 DNA binding domain-PARP fusion protein was cotransfected into COS1 cells with a luciferase reporter plasmid containing five Gal4 binding sites. Compared with cells cotransfected with the reporter construct and Gal4 DNA binding domain, luciferase activity was lower in cells cotransfected with pM-PARP. The C908R mutation, which results in loss of poly(ADP-ribosyl) enzyme activity, eliminated the repressor activity of the protein. All luciferase activity was corrected for transfection efficiency by measuring β-galactosidase activity of cells transfected together. The results represent averages and standard deviations from three independent experiments.