“…In other words, MMR can utilize a nick on either side of the mismatch. With the help of MutL, this nick in the nascent strand acts as a point of entry for helicase II that unwinds the nascent strand, a process that is facilitated by single-strand binding protein (SSB) (Matson and Robertson, 2006;Robertson et al, 2006b). This exposes the strand to digestion by one of four single-strand exonucleases having either 3′-5′ or 5′-3′ polarity: ExoI, ExoVII, ExoX, or RecJ (Burdett et al, 2001).…”