The -nick-(a) and -nick-(b) directed eukaryotic MMR. After recognition of a mismatched base by , incises the discontinuous strand of the heteroduplex in a mismatch--, PCNA-, RFC-, and ATP-dependent manner [10, 30, 31]. Incisions by occur dominantly on the distal side of the mismatched base relative to the pre-existed strand break although it can also occur proximal to the mismatch [30].
