Initiation assay with the unwinding defective PPP-DBP mutant on 0.3 pmol of origin-containing templates. Indicated are the 5′ gaps ranging from 0 to 50 nucleotides. The amount of stimulation of initiation is shown. The pTP-C signal without the addition of PPP-DBP was set to 1 for each template. The basal level of initiation (no PPP-DBP) on TD50 was set to 1, and the basal levels of initiation of the other templates were determined as follows: TDΔ5, 3.3; TDΔ10, 0.4; TDΔ15, 0.3; TDΔ20, 0.3; and T50, 0.4.