Purified apolipoprotein B gene regulatory factor-3 is DNA topoisomerase I
| Autor: | Samuel S. Chuang, Deben Banerjee, Hriday K. Das |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
Transcription
Genetic Molecular Sequence Data Biology Biochemistry Chromatography Affinity Chromatography DEAE-Cellulose chemistry.chemical_compound Exon Affinity chromatography Animals Humans Amino Acid Sequence Binding site Gene Apolipoproteins B Cell Nucleus chemistry.chemical_classification Base Sequence Sequence Homology Amino Acid Oligonucleotide Molecular biology Peptide Fragments Rats Amino acid Blot Kinetics DNA Topoisomerases Type I Gene Expression Regulation Liver Oligodeoxyribonucleotides chemistry Sequence Alignment DNA |
| Zdroj: | European Journal of Biochemistry. 263:773-781 |
| ISSN: | 1432-1033 0014-2956 |
| DOI: | 10.1046/j.1432-1327.1999.00555.x |
| Popis: | Hepatic cell-specific expression of the human apolipoprotein B (apoB) gene is controlled by at least four cis-acting elements located between positions −128 and +122 [Chuang, S. S., & Das, H. K. (1996) Biochem. Biophys. Res. Commun.220, 553–562]. A negative cis-acting element (+20 to +40) is located in the first nontranslated exon of the human apoB gene, and apoB regulatory factor-3 (BRF-3) interacts with this. In this paper, we report the purification and characterization of BRF-3 from rat liver nuclear extracts. BRF-3 has been purified to apparent homogeneity by DEAE–cellulose, heparin–agarose, and DNA-specific affinity chromatography. Purified BRF-3 produced two polypeptide bands with apparent molecular masses of 70 kDa and 67 kDa in SDS/PAGE as detected by silver staining. Both 70-kDa and 67-kDa proteins have been found to hybridize specifically with labeled double-stranded oligonucleotide containing BRF-3 binding site in a South-Western blot. Double-stranded oligonucleotide containing mutations in the BRF-3 binding site was found to abolish DNA binding by these two proteins. Amino acid sequences of tryptic peptides derived from affinity purified 70-kDa and 67-kDa rat BRF-3 proteins were found to have 100% sequence homologies with DNA topoisomerase I. These data suggest that the 70-kDa and 67-kDa forms of BRF-3 are derived by proteolytic cleavage of topoisomerase I, and therefore, topoisomerase I may play an important role in transcriptional regulation of apoB. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|