FIG. 2.
TBPc inhibits E2-stimulated replication and does not affect E2-independent replication. (A) NdeI-digested replication products from cell-free replication assays using HPV-11 ori-containing plasmid (pUC18/7870-99) and increasing TBPc. Cell-free replication assays were performed as outlined in Materials and Methods. E1, E2, and TBPc are added as noted. Lanes correlating to initial and base intensity of counts (I0 and Ibase) are indicated. (B) Several E2-stimulated (circles) and E2-independent (squares) replication assays with increasing TBPc concentration were quantified by PhosphoImager and filter washing as outlined in Materials and Methods. Data were normalized to E2-stimulated replication. The data were fit to 2-parameter hyperbolic decay (r2 = 0.96 with E2 present) and first-order polynomial regression curves (y-intercept = 0.657; correlation coefficient = 1.12 × 10−5 without E2 present). Analysis of 2-parameter hyperbolic decay yields an IC50 of 0.56 nM.