Checkpoint controls in Schizosaccharomyces pombe: rad1

EMBO J. 1992 Apr;11(4):1335-42.


'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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Cell Cycle / drug effects
  • Cell Cycle / genetics
  • Cell Cycle / radiation effects
  • DNA Repair
  • DNA Replication / radiation effects
  • Dose-Response Relationship, Radiation
  • Gamma Rays
  • Genotype
  • Hydroxyurea / pharmacology
  • Kinetics
  • Mutation*
  • Phenotype
  • Schizosaccharomyces / genetics
  • Schizosaccharomyces / growth & development
  • Schizosaccharomyces / radiation effects*


  • Hydroxyurea