Figure 3

Split FRs distinguish between the replication factor titration and replication fork barrier models. (A) Schematic representation of the oriP region from plasmids designed to distinguish between the replication factor titration and the replication fork barrier models. The identity of the plasmid is indicated to the left of each schematic. DS is represented as a striped oval, and the EBNA1-binding sites in FR as filled black circles. The number of EBNA1 binding sites within each FR is indicated above each FR. FRs are separated from each other (plasmid AGP213) or from DS (plasmid AGP212) by the EBV sequences normally present between FR and DS. (B) Stable replication of oriP replication reporters under selection in 293/EBNA1 cells. 293/EBNA1 cells were transfected with the indicated plasmid, placed under puromycin selection for 18 days, at which time replicated Dpn I-resistant episomal DNAs were recovered and quantified as described in the Methods. "M" indicates the migration position of standards used for quantitation, and the amounts of standards loaded are indicated above each lane. The identity of the transfected plasmid is indicated above each lane. "A" indicates the migration position of Dpn I-resistant, linearized plasmid DNAs.