title: The budding yeast Rad9 checkpoint complex: chaperone proteins are required for its function.
abstract: Rad9 functions in the DNA-damage checkpoint pathway of Saccharomyces cerevisiae. In whole-cell extracts, Rad9 is found in large, soluble complexes, which have functions in amplifying the checkpoint signal. The two main soluble forms of Rad9 complexes that are found in cells exposed to DNA-damaging treatments were purified to homogeneity. Both of these Rad9 complexes contain the Ssa1 and/or Ssa2 chaperone proteins, suggesting a function for these proteins in checkpoint regulation. Consistent with this possibility, genetic experiments indicate redundant functions for SSA1 and SSA2 in survival, G2/M-checkpoint regulation, and phosphorylation of both Rad9 and Rad53 after irradiation with ultraviolet light. Ssa1 and Ssa2 can now be considered as novel checkpoint proteins that are likely to be required for remodelling Rad9 complexes during checkpoint-pathway activation.
authors.affiliation: Cancer Research UK, Clare Hall Laboratories, South Mimms, Hertfordshire EN6 3LD, UK.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Gilbert
authors.forename: Michael
authors.initials: M
authors.lastname: van den Bosch
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Green
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Vialard
authors.forename: Muriel
authors.initials: M
authors.lastname: Grenon
authors.forename: Hediye
authors.initials: H
authors.lastname: Erdjument-Bromage
authors.forename: Paul
authors.initials: P
authors.lastname: Tempst
authors.forename: Noel F
authors.initials: NF
authors.lastname: Lowndes
mesh_terms: D000251:Adenosine Triphosphatases; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002470:Cell Survival; D004249:DNA Damage; D004260:DNA Repair; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D018816:Genes, cdc; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D046911:Macromolecular Substances; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D018840:HSP70 Heat-Shock Proteins; D046911:Macromolecular Substances; D018832:Molecular Chaperones; C542288:SSA2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C069930:rad9 protein; D000251:Adenosine Triphosphatases; C095973:SSA1 protein, S cerevisiae