Saccharomyces cerevisiae (Scer) Pms1 and Mlh3 amino acid sequences are shown, followed by sequences from homologs from six of the 18 species. The metal binding site of Pms1 (green font), which forms the endonuclease active site, contains five residues (H703, E707, C817, C848, H850) that are highly conserved (100% identity in 18 Pms1 and 18 Mlh3 sequences; Clark, Alani, & Aquadro, 2012). The QXLXXP motif (blue font), important for interactions with PCNA (PIP), is highly conserved in the Pms1 sequences (>94% identity; Genschel et al., 2017), but is absent in Mlh3 sequences. Also shown are residues in red that are uniquely conserved (61 to 100% identity) within each Pms1 and Mlh3 homolog family. Homologs were obtained from Saccharomyces cerevisiae (Scer), Ashbya gossypii (Agos), Candida albicans (Calb), Candida dubliniensis (Cdub), Candida glabrata (Cgla), Candida guilliermondii (Cgui), Candida tropicalis (Ctro), Saccharomyces paradoxus, Saccharomyces mikatae, Saccharomyces bayanus, Saccharomyces kluyveri, Kluyveromyces thermotolerans, Kluyveromyces waltii, Kluyveromyces lactis, Kluyveromyces polysporus, Candida lusitaniae, Lodderomyces elongisporus, Debaryomyces hansenii, and Pichia stipitis. Because of incomplete sequence information, the Pms1 homolog for Debaryomyces hansenii, and the Mlh3 homolog of Candida lusitaniae were not included.