Mcm4,6,7 trimer forms and associates with the replication fork

Stable Identifier
Reaction [dissociation]
Homo sapiens
Rearrangement and mobilization of Mcm2-7
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At the start of the elongation phase of DNA replication, the Mcm2-7 complex may re-arrange to function as the replicative helicase associated with the replication fork. In general, a replicative helicase is associated with the replication fork and unwinds DNA ahead of the polymerase. In yeast, the Mcm proteins associate with origin DNA in G1 phase and then exit the origin upon replication initiation, consistent with moving out of the origin with the replication fork. The Mcm2-7 complex is a ring-shaped hexamer. Complexes of Mcm4, Mcm6 and Mcm7 proteins from humans or S. pombe display a modest ATP-dependent helicase activity in vitro. Consistent with the hypothesis that eukaryotic Mcm complexes function as helicases, an archaeal Mcm homolog is a ring-shaped double hexamer that has a processive DNA unwinding activity. Mcm proteins may have additional functions during elongation, as uninterrupted function of all six is required for replication fork progression in budding yeast. Mcm4,6,7 helicase activity may be negatively regulated in two ways. Mcm2, Mcm4, Mcm6, and Mcm7 also form a stable complex which, however, has no helicase activity, suggesting that Mcm2 inhibits DNA unwinding by Mcm4,6,7. In addition, phosphorylation of human Mcm4,6,7 complex by CDK inhibits its helicase activity.
Literature References
PubMed ID Title Journal Year
10884341 Electron microscopic observation and single-stranded DNA binding activity of the Mcm4,6,7 complex.

Ishimi, Y, Gotow, T, Komamura-Kohno, Y, You, Z, Sato, M, Nojima, H, Uchiyama, Y, Yabuta, N

J Mol Biol 2000
12364596 Human Mcm proteins at a replication origin during the G1 to S phase transition.

Knippers, R, Keller, C, Schaarschmidt, D, Ladenburger, EM

Nucleic Acids Res 2002
Orthologous Events
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