title: Subcellular localization and protein-protein interaction regions of Ku proteins.
abstract: The Ku protein is a complex of Ku70 and Ku80 subunits and is capable of binding promoters in a sequence-specific manner, although it remains unclear whether Ku is involved in transcriptional regulation. We examined the subcellular localization and determined the interaction regions of Ku. Our results indicate that heterodimers of Ku70 and Ku80 are localized in the nucleus, and that the stretches from amino acid (aa) 378 to 482 of Ku70 and from aa 374 to 502 of Ku80 are necessary for heterodimerization. These interaction regions do not contain any previously recognized protein-protein interaction motifs. To determine whether Ku contains a potential transcriptional activation domain, we examined N- and C-terminal deletion mutants of Ku70 and Ku80 for their ability to activate transcription in the GAL4-based one-hybrid system. We found that the whole Ku protein had no transcriptional activity, although the N-terminal peptide fragment of Ku70 was capable of activating transcription of the HIS3 and lacZ reporter genes in yeast cells.
authors.affiliation: Genome Research Group, National Institute of Radiological Sciences, 4-9-1 Anagawa, Chiba, Inage-ku, 263-8555, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Koike
authors.forename: T
authors.initials: T
authors.lastname: Miyasaka
authors.forename: T
authors.initials: T
authors.lastname: Mimori
authors.forename: T
authors.initials: T
authors.lastname: Shiomi
mesh_terms: D034961:Antigens, Nuclear; D001324:Autoantigens / Q000235:genetics / Q000378:metabolism*; D004265:DNA Helicases; D004260:DNA Repair; D018076:DNA, Complementary / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D006367:HeLa Cells; D006801:Humans; D000072200:Ku Autoantigen; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces; D013347:Subcellular Fractions / Q000737:chemistry; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D034961:Antigens, Nuclear; D001324:Autoantigens; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C081647:high affinity DNA-binding factor, S cerevisiae; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen