title: Checkpoint controls in Schizosaccharomyces pombe: rad1.
abstract: 'Checkpoint' controls ensure that the events of the cell cycle are completed in an orderly fashion. For example, such controls delay mitosis until DNA synthesis and repair of radiation-induced DNA damage are complete. The rad series of radiosensitive fission yeast mutants was examined to identify strains deficient for the DNA damage-responsive checkpoint control. Five were identified. A characterization of one (rad1-1) and the wild-type is presented. The rad1-1 mutant does not arrest after irradiation, is sensitive to killing by radiation and is not arrested by hydroxyurea, and thus is also deficient for the DNA synthesis-responsive checkpoint control. The radiosensitivity of the rad1-1 mutant was greatly reduced when irradiated and maintained for 6 h in a non-dividing (density inhibited) state, demonstrating that rad1-1 is repair proficient and radiosensitive only through failure to delay. The checkpoint controls for which rad1 is required appear to regulate G2-M progression through the activity of cdc2, here implicated in this role by the coincidence of the radiation transition point and the cdc2 execution point.
authors.affiliation: Department of Radiology, University of Utah Medical Center, Salt Lake City 84132.
authors.forename: R
authors.initials: R
authors.lastname: Rowley
authors.forename: S
authors.initials: S
authors.lastname: Subramani
authors.forename: P G
authors.initials: PG
authors.lastname: Young
mesh_terms: D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D004260:DNA Repair; D004261:DNA Replication / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays; D005838:Genotype; D006918:Hydroxyurea / Q000494:pharmacology; D007700:Kinetics; D009154:Mutation; D010641:Phenotype; D012568:Schizosaccharomyces / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects*
chemical_list: D006918:Hydroxyurea