Members of this family adopt a secondary structure consisting of two beta sheets and one alpha helix, arranged as a beta-alpha-beta motif. Each beta sheet has five strands, arranged in a 32145 order, with the second strand being antiparallel to the rest. Mitochondrial resolvase Ydc2 is capable of resolving Holliday junctions and cleaves DNA after 5'-CT-3' and 5'-TT-3' sequences [1]. This family also contains the mitochondrial RNA-splicing protein MRS1 which is involved in the excision of group I introns [2-3].

1: Crystal structure of the fission yeast mitochondrial Holliday junction resolvase Ydc2. Ceschini S, Keeley A, McAlister MS, Oram M, Phelan J, Pearl LH, Tsaneva IR, Barrett TE; EMBO J. 2001;20:6601-6611. PMID:11726496

2: Splicing of yeast aI5beta group I intron requires SUV3 to recycle MRS1 via mitochondrial degradosome-promoted decay of excised intron ribonucleoprotein (RNP). Turk EM, Caprara MG; J Biol Chem. 2010;285:8585-8594. PMID:20064926

3: Cloning of a nuclear gene MRS1 involved in the excision of a single group I intron (bI3) from the mitochondrial COB transcript in S. cerevisiae. Kreike J, Schulze M, Pillar T, Korte A, Rodel G; Curr Genet. 1986;11:185-191. PMID:2834089