FIG. 3.

GΔ228-Uve1p requires divalent cations for mismatch recognition. 5′-end-labeled duplex *CX/AY-31mer was incubated with GΔ228-Uve1p (lanes 1 and 4) or buffer only (control [CON]; lanes 2 and 5) in the presence (lanes 1 and 2) or absence (lanes 4 and 5) of Mn²⁺. C* indicates base mismatch site. Arrows a and b indicate Uve1p cleavage positions. E. coli endonuclease (Endo) V-reacted oligonucleotide (arrow v, lane 3) and C+T and G+A sequencing ladders included as nucleotide position markers are marked. Bands below arrow b (indicated by asterisks) correspond to shortened products due to 3′-to-5′ exonuclease activity (described in the legend to Fig. 2).