MCM3 Complex Required for Cell Cycle Regulation of DNA Replication in Vertebrate Cells

Nature. 1995 Jun 1;375(6530):421-4. doi: 10.1038/375421a0.


An intact nuclear membrane restricts DNA replication to only one round in each cell cycle, apparently by excluding an essential replication-licensing factor throughout interphase. A family of related yeast replication proteins, MCM2, 3 and 5 (also called, after cell-division cycle, CDC46), resemble licensing factor, entering the nucleus only during mitosis. We have cloned a Xenopus homologue of MCM3 (XMCM3) and raised antibodies against expressed protein. Immunodepletion of Xenopus egg extracts removes a complex of MCM2, 3 and 5 homologues and inhibits replication of Xenopus sperm nuclei or permeable G2 HeLa nuclei. However, G1 HeLa nuclei still replicate efficiently. Mock-depleted extracts replicate all three templates. XMCM3 accumulates in nuclei before replication but anti-XMCM3 staining decreases during replication. These results can explain why replicated nuclei are unable to reinitiate replication in a single cell cycle.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cell Cycle / physiology*
  • Cell Cycle Proteins / physiology*
  • Cloning, Molecular
  • DNA Primers
  • DNA Replication / physiology*
  • DNA-Binding Proteins
  • Fungal Proteins / physiology
  • HeLa Cells
  • Humans
  • Male
  • Minichromosome Maintenance Complex Component 3
  • Molecular Sequence Data
  • Nuclear Proteins
  • Oocytes
  • Saccharomyces cerevisiae / genetics
  • Spermatozoa
  • Xenopus laevis


  • Cell Cycle Proteins
  • DNA Primers
  • DNA-Binding Proteins
  • Fungal Proteins
  • MCM3 protein, human
  • Nuclear Proteins
  • Minichromosome Maintenance Complex Component 3

Associated data

  • GENBANK/U26057