G1-phase and B-type cyclins exclude the DNA-replication factor Mcm4 from the nucleus.
Cyclin-dependent kinases (CDKs) activate the firing of replication origins during the S phase of the cell cycle. They also block re-initiation of DNA replication within a single cell cycle, by preventing the assembly of prereplicative complexes at origins. We show here that, in budding yeast, CDKs exclude the essential prereplicative-complex component Mcm4 from the nucleus. Although origin firing can be triggered by the B-type cyclins only, both G1-phase and B-type cyclins cause exit of Mcm4 from the nucleus. These results suggest that G1 cyclins may diminish the cell's capacity to assemble prereplicative complexes before B-type cyclins trigger origin firing during S phase.
Labib
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ICRF Clare Hall Laboratories, South Mimms, Hertfordshire, EN6 3LD, UK.
Diffley
J F
JF
Kearsey
S E
SE
D017489:CDC28 Protein Kinase, S cerevisiae / Q000378:metabolism; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D002843:Chromatin / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D016213:Cyclins / Q000378:metabolism*; D004261:DNA Replication / Q000235:genetics / Q000502:physiology; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D016193:G1 Phase / Q000502:physiology*; D017930:Genes, Reporter / Q000235:genetics; D064148:Minichromosome Maintenance Complex Component 4; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016196:S Phase / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins
C066503:CDC6 protein, S cerevisiae; D018797:Cell Cycle Proteins; D002843:Chromatin; D016213:Cyclins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D017489:CDC28 Protein Kinase, S cerevisiae; D018844:Cyclin-Dependent Kinases; C092802:MCM4 protein, S cerevisiae; D064148:Minichromosome Maintenance Complex Component 4