title: Redistribution of BRCA1 among four different protein complexes following replication blockage.
abstract: The BRCA1 protein is known to participate in multiple cellular processes. In these experiments, we resolved four distinct BRCA1-containing complexes. We found BRCA1 associated with the RNA polymerase II holoenzyme (holo-pol), a large mass complex called the fraction 5 complex, the Rad50-Mre11-Nbs1 complex, and a complex that has not been described previously. We observed this new complex after treating cells with hydroxyurea, suggesting that the hydroxyurea-induced complex (HUIC) is involved with the response to DNA replication blockage. After hydroxyurea treatment of cells, BRCA1 content decreased in the holo-pol and the fraction 5 complex, and BRCA1 was redistributed to the HUIC. The HUIC was shown not to contain a number of holo-pol components or the Rad50-Mre11-Nbs1 complex but was associated with the BRCA1-associated RING domain protein BARD1. These data suggest that BRCA1 participates in multiple cellular processes by multiple protein complexes and that the BRCA1 content of these complexes is dynamically altered after DNA replication blockage.
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: N
authors.initials: N
authors.lastname: Chiba
authors.forename: J D
authors.initials: JD
authors.lastname: Parvin
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D019313:BRCA1 Protein / Q000096:biosynthesis* / Q000737:chemistry* / Q000302:isolation & purification*; D001671:Biochemistry / Q000379:methods; D002460:Cell Line; D004247:DNA / Q000096:biosynthesis / Q000378:metabolism; D004268:DNA-Binding Proteins; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; D005656:Fungal Proteins / Q000378:metabolism; D005822:Genetic Vectors; D006367:HeLa Cells; D020035:Holoenzymes / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D015151:Immunoblotting; D009687:Nuclear Proteins / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D012319:RNA Polymerase II / Q000737:chemistry* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D019313:BRCA1 Protein; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D020035:Holoenzymes; D009687:Nuclear Proteins; C086930:RAD50 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA; D012319:RNA Polymerase II; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; C094191:MRE11 protein, S cerevisiae; D006918:Hydroxyurea