<p> MCM proteins are DNA-dependent ATPases required for the initiation ofeukaryotic DNA replication [<cite idref="PUB00004410"/>, <cite idref="PUB00004436"/>, <cite idref="PUB00005507"/>]. In eukaryotes there is a family of six proteins, MCM2 to MCM7. They were first identified in yeast where most of them have adirect role in the initiation of chromosomal DNA replication by interacting directly with autonomously replicating sequences (ARS). They were thus called minichromosome maintenance proteins, MCM proteins [<cite idref="PUB00004422"/>].</p><p>This family is also present in the archebacteria in 1 to 4 copies. <taxon tax_id="2190">Methanocaldococcus jannaschii</taxon> (Methanococcus jannaschii) has four members, MJ0363, MJ0961, MJ1489 and MJECL13.</p><p>The "MCM motif" contains Walker-A and Walker-B type nucleotide binding motifs. The diagnostic sequence defining the MCMs is IDEFDKM. Only Mcm2 (aka Cdc19 or Nda1) has been subjected to mutational analysis in this region, and most mutations abolish its activity [<cite idref="PUB00006394"/>]. The presence of a putative ATP-binding domain implies that these proteins may be involved in an ATP-consuming step in the initiation of DNA replication in eukaryotes.</p><p>The MCM proteins bind together in a large complex [<cite idref="PUB00006390"/>].Within this complex, individual subunits associate with different affinities, and there is a tightly associated core of Mcm4 (Cdc21), Mcm6 (Mis5) and Mcm7 [<cite idref="PUB00006498"/>]. This core complex in human MCMs has been associated with helicase activity <i>in vitro</i> [<cite idref="PUB00006384"/>], leading to the suggestion that the MCM proteins are the eukaryotic replicative helicase.</p><p> <taxon tax_id="4896">Schizosaccharomyces pombe</taxon> (Fission yeast) MCMs, like those in metazoans, are found in the nucleus throughout the cell cycle. This is in contrast to the <taxon tax_id="4932">Saccharomyces cerevisiae</taxon> (Baker's yeast) in which MCM proteins move in and out of the nucleus during each cell cycle. The assembly of the MCM complex in S. pombe is required for MCM localisation, ensuring that only intact MCM complexes remain in the nucleus [<cite idref="PUB00006510"/>].</p><p>The signature pattern used in this entry represents a perfectly conserved region that is a special version of the B motif found in ATP-binding proteins.</p> Mini-chromosome maintenance, conserved site