Reference : A TEF-1 binding motif that interacts with a placental protein is important for the tr...
Scientific journals : Article
Life sciences : Biochemistry, biophysics & molecular biology
A TEF-1 binding motif that interacts with a placental protein is important for the transcriptional activity of the hCS-B enhancer
Jacquemin, P. [> > > >]
Oury, Cécile mailto [Université de Liège - ULg > Département des sciences biomédicales et précliniques > GIGA-R : Génétique générale et humaine >]
Belayew, A. [> > > >]
Martial, Joseph mailto [Université de Liège - ULg > Département des sciences de la vie > GIGA-R : Biologie et génétique moléculaire >]
DNA & Cell Biology
Mary Ann Liebert, Inc.
Yes (verified by ORBi)
[en] Base Sequence ; Cell Line ; DNA-Binding Proteins/*metabolism ; *Enhancer Elements, Genetic ; Hela Cells ; Humans ; Molecular Sequence Data ; Molecular Weight ; Nuclear Proteins/*metabolism ; Oligodeoxyribonucleotides ; Peptides/metabolism ; Placental Lactogen/*genetics/metabolism ; Point Mutation ; Protein Binding ; Transcription Factors/*metabolism
[en] The transcriptional activity of the human placental lactogen genes (choriosomatomammotropic hormone, hCS) is controlled by tissue-specific enhancers located 4 kb downstream from their respective origins of transcription. The hCS-B enhancer is the strongest; its activity is mediated by synergism between two protein-binding sites (DF-3 and DF-4). The DF-4 site possesses a potential binding sequence for TEF-1, a known transcription factor. In this paper, we show by electrophoretic mobility-shift assays and antibody supershift experiments that TEF-1 does not bind to site DF-4. Mutations in the TEF-1-like binding motif of site DF-4 prevent formation of the DNA-protein complex, called complex f, in the presence of placental JEG-3 cell extracts. When HeLa cell extracts are used, another complex (complex c) is also affected. In transient expression experiments, TKCAT constructs linked to this mutated DF-4 site exhibit greatly reduced transcriptional activity when introduced into JEG-3 cells. Some cell lines contain both protein c and protein f (the proteins forming complexes c and f); when transfected, these lines display reduced DF-4-driven activity, suggesting that the two proteins could compete for the same DF-4 sequence. We conclude that protein f is important for the placenta-specific activity of the hCS-B enhancer. By UV cross-linking, we show that protein f is actually three polypeptides ranging in size from about 12 to 21 kD.

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