FIGURE 1.
Equilibration of DNA substrates between 5′-single flap and 3′/5′-double flap species. DNA substrates used in this study have a common nucleotide on the 3′-end of the upstream strand and 1 nt into the flap on the FlapX strand, thus allowing the substrate to equilibrate between a 5′-single flap X nt in length and a 3′/5′-double flap. FEN1 will cleave the single flap substrate at the base of the flap and the double flap substrate 1 nt downstream of the base of the 5′-flap, yielding products x nt in length.