The MCM (minichromosome maintenance) family comprise DNA helicases sharing a common 'MCM domain'. MCM2-7 form a heterohexameric complex that is essential for initiation of DNA replication and also acts during elongation as the replicative helicase. MCM8 and MCM9 are not part of this complex - they have roles in replication elongation, meiotic recombination and DNA repair. MCM8 and 9 arose early during eukaryotic evolution, though one or both have been lost in multiple lineages: in mammals, MCM8 and MCM9 form a functional heterodimeric complex; D. melanogaster and related species possess MCM8 only; while other species (e.g. yeast, C. elegans) have neither. (Adapted from
PMID:23412083,
PMID:30743181 and
FBrf0188222.)
