Abstract
YB-1 is a multifunctional protein involved in the regulation of transcription, translation, mRNA splicing and probably DNA repair. It contains a conserved cold shock domain and it binds strongly to inverted CCAAT box of different promoters. In this study, we have found that purified YB-1 oligomerizes readily in solutions to form trimers, hexamers and oligomers of 12 molecules. The presence of ATP changed the conformation of YB-1 in such a way that only dimers were detected by gel filtration analyses. Purified YB-1 can separate different DNA duplexes containing blunt ends, 5' or 3' recessed ends, or forked structures. This strand separation activity is increased on cisplatin-modified DNA or with duplex molecules containing mismatches. In addition to its exonuclease activity, YB-1 exhibits endonucleolytic activities in vitro. Finally, YB-1 affinity chromatography experiments have indicated that in addition to prespliceosome factors like nucleolin and ALY, YB-1 binds the DNA repair proteins MSH2, DNA polymerase delta, Ku80 and WRN proteins in vitro. Furthermore, immunofluorescence studies have shown that YB-1 re-localizes from the cytoplasm to nuclear areas containing either Ku80 or MSH2 proteins in human 293 embryonic kidney cells. These results suggest that YB-1 is involved in base excision and mismatch repair pathways.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adenosine Triphosphate / metabolism
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Antigens, Nuclear / metabolism
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Base Pair Mismatch*
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Base Pairing* / drug effects
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Base Sequence
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Catalysis
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Cell Line
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Cell Nucleus / metabolism
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Chromatography, Affinity
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Cisplatin / metabolism*
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Cisplatin / pharmacology
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DNA / chemistry
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DNA / genetics
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DNA / metabolism*
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DNA Helicases*
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DNA Repair*
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DNA-Binding Proteins / chemistry
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / isolation & purification
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DNA-Binding Proteins / metabolism*
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Endonucleases / chemistry
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Endonucleases / genetics
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Endonucleases / isolation & purification
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Endonucleases / metabolism*
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Humans
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Ku Autoantigen
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MutS Homolog 2 Protein
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Nuclear Proteins
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Nucleic Acid Denaturation / drug effects
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Protein Binding
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Protein Structure, Quaternary
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Protein Transport
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Proto-Oncogene Proteins / metabolism
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Sequence Deletion
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Substrate Specificity
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Transcription Factors / chemistry
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Transcription Factors / genetics
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Transcription Factors / isolation & purification
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Transcription Factors / metabolism*
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Y-Box-Binding Protein 1
Substances
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Antigens, Nuclear
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DNA-Binding Proteins
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Nuclear Proteins
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Proto-Oncogene Proteins
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Transcription Factors
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Y-Box-Binding Protein 1
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YBX1 protein, human
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Adenosine Triphosphate
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DNA
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Endonucleases
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MSH2 protein, human
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MutS Homolog 2 Protein
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DNA Helicases
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XRCC5 protein, human
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Xrcc6 protein, human
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Ku Autoantigen
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Cisplatin