title: Cyclin/Cdk-dependent initiation of DNA replication in a human cell-free system.
abstract: We describe a cell-free system from HeLa cells that initiates DNA replication under cell cycle control. G1 but not G2 phase nuclei initiate replication when coincubated with S phase nuclei in cytosolic extracts from S phase but not from G1 or G2 phase HeLa cells. S phase nuclei or an S phase nuclear extract are required for the initiation of semiconservative DNA replication in G1 nuclei but not for elongation in S phase nuclei. S phase nuclear extract could be replaced by recombinant human cyclins A and E complexed to Cdk2 but not by Cdk2 alone or by human cyclin B1 complexed to Cdc2. In S phase cytosol, cyclins A/Cdk2 and E/Cdk2 triggered initiation synergistically.
authors.affiliation: Wellcome Trust/Cancer Research Campaign Institute, University of Cambridge, United Kingdom.
authors.forename: T
authors.initials: T
authors.lastname: Krude
authors.forename: M
authors.initials: M
authors.lastname: Jackman
authors.forename: J
authors.initials: J
authors.lastname: Pines
authors.forename: R A
authors.initials: RA
authors.lastname: Laskey
mesh_terms: D042846:CDC2-CDC28 Kinases; D002457:Cell Extracts; D002467:Cell Nucleus / Q000378:metabolism; D002474:Cell-Free System; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases / Q000502:physiology*; D016213:Cyclins / Q000502:physiology*; D004261:DNA Replication / Q000502:physiology*; D016193:G1 Phase / Q000502:physiology*; D016195:G2 Phase / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D016196:S Phase / Q000502:physiology*
chemical_list: D002457:Cell Extracts; D016213:Cyclins; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases