FIG. 5.

Uve1p incises only one strand of a duplex containing a base mismatch. (A) 3′-end-labeled *CX/AY-41mer was incubated with restriction enzyme DdeI (lane 1), GΔ228-Uve1p (lane 2), or buffer (lane 3). The reaction products were analyzed on a nondenaturing gel as described in the text for the presence of DNA double-strand break products (arrow dsb). Arrows b and c indicate the primary cleavage site for Uve1p on this substrate. (B) 3′-end-labeled *CX/AY-41mer or CX/*AY-41mer was incubated with GΔ228-Uve1p (+ lanes) or buffer (− lanes) and analyzed on denaturing, DNA sequencing-type gels as described in the text. Arrows b and c indicate positions of major Uve1p cleavage events relative to the mismatched base (asterisk) position. G+A and C+T base-specific sequencing ladders are included in outside lanes as nucleotide position markers.