(A) Initiation assay on 0.3 pmol of the TD50 template with various concentrations of DBP. A representative initiation assay is shown. The average level of initiation based on three independent experiments is graphically represented. (B) Initiation assay on origin-containing templates with increasing 5′ gaps. Equimolar amounts of DNA templates (0.3 pmol) were used. The fold stimulation of initiation by DBP of a representative experiment is shown. The pTP-C signal without the addition of DBP was set to 1 for each template. The basal level of initiation (no DBP) on TD50 was set to 1, and the basal levels of initiation of the other templates were determined as follows: TDΔ5, 2.5; TDΔ10, 0.6; TDΔ15, 0.7; TDΔ20, 0.3; and T50, 0.3.