FIG. 8.

Mutational analysis of pX. (A) A set of two-codon insertion mutants of pX (M1 to M14) was used in a coactivation assay; fold coactivation and repression by pX mutants was calculated and is shown along the X ORF at the corresponding regions. For this assay, the Gal4-luciferase reporter was cotransfected with Gal4-p53 activator with or without pX expressor plasmids. Also shown are the regions involved in POLII and TFIIB binding. (B) pHA-TFIIB- and pflag-X (and corresponding mutant)-transfected cell extracts were immunoprecipitated with anti-flag and analyzed by anti-TFIIB immunoblotting.