MCM3 complex required for cell cycle regulation of DNA replication in vertebrate cells.
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.
Madine
M A
MA
Wellcome/CRC Institute, Cambridge, UK.
Khoo
C Y
CY
Mills
A D
AD
Laskey
R A
RA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002453:Cell Cycle / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000502:physiology*; D003001:Cloning, Molecular; D017931:DNA Primers; D004261:DNA Replication / Q000502:physiology*; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D008297:Male; D064126:Minichromosome Maintenance Complex Component 3; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D009865:Oocytes; D012441:Saccharomyces cerevisiae / Q000235:genetics; D013094:Spermatozoa; D014982:Xenopus laevis
D018797:Cell Cycle Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C066470:MCM3 protein, human; D009687:Nuclear Proteins; D064126:Minichromosome Maintenance Complex Component 3