A novel Rad24 checkpoint protein complex closely related to replication factor C.
Rad24 functions in the DNA damage checkpoint pathway of Saccharomyces cerevisiae. Here, analysis of Rad24 in whole cell extracts demonstrated that its mass was considerably greater than its predicted molecular weight, suggesting that Rad24 is a component of a protein complex. The Rad24 complex was purified to homogeneity. In addition to Rad24, the complex included polypeptides of 40 kDa and 35 kDa. The 40 kDa species was found by mass spectrometry to contain Rfc2 and Rfc3, subunits of replication factor C (RFC), a five subunit protein that is required for the loading of polymerases onto DNA during replication and repair [3]. We hypothesised that other RFC subunits, all of which share sequence homologles with Rad24, might also be components of the Rad24 complex. Reciprocal co-immunoprecipitation studies were performed using extracts prepared from strains containing epitope-tagged RFC proteins. These experiments showed that the small RFC proteins, Rfc2, Rfc3, Rfc4 and Rfc5, interacted with Rad24, whereas the Rfc1 subunit did not. We suggest that this RFC-like Rad24 complex may function as a structure-specific sensor in the DNA damage checkpoint pathway.
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Imperial Cancer Research Fund, Clare Hall Laboratories, Hertfordshire, UK.
Erdjument-Bromage
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D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000302:isolation & purification / Q000502:physiology*; D004249:DNA Damage; D004261:DNA Replication / Q000502:physiology*; D004271:DNA, Fungal / Q000096:biosynthesis / Q000235:genetics; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000502:physiology*; D005656:Fungal Proteins / Q000302:isolation & purification / Q000502:physiology*; D018398:Homeodomain Proteins; D047908:Intracellular Signaling Peptides and Proteins; D046911:Macromolecular Substances; D015778:Minor Histocompatibility Antigens; D008970:Molecular Weight; D019253:Proto-Oncogene Proteins c-bcl-2; D051818:Replication Protein C; D012097:Repressor Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins
C096816:BCL2-related protein A1; D018797:Cell Cycle Proteins; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D018398:Homeodomain Proteins; D047908:Intracellular Signaling Peptides and Proteins; C096063:MATA1 protein, S cerevisiae; D046911:Macromolecular Substances; D015778:Minor Histocompatibility Antigens; D019253:Proto-Oncogene Proteins c-bcl-2; C088385:RAD24 protein, S cerevisiae; C084903:RFC1 protein, S cerevisiae; C087491:RFC2 protein, S cerevisiae; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D051818:Replication Protein C