Related Experiment Video
Updated: Sep 9, 2026

Reverse Yeast Two-hybrid System to Identify Mammalian Nuclear Receptor Residues that Interact with Ligands and/or Antagonists
Published on: November 15, 2013
A DNA-binding factor specific for xenobiotic responsive elements of P-450c gene exists as a cryptic form in
A Fujisawa-Sehara1, M Yamane, Y Fujii-Kuriyama
1Department of Biochemistry, Cancer Institute, Japanese Foundation for Cancer Research, Tokyo.
Abstract:
Transcription of the drug-metabolizing cytochrome P-450c gene is induced by 3-methylcholanthrene or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Previously, we defined two xenobiotic responsive elements (XREs) of approximately equal to 15 base pairs, both of which activate transcription in cis in response to these xenobiotics. Using a gel mobility shift assay, we have identified a factor that specifically binds to the XREs. This factor appears in nuclei of mouse hepatoma cell line Hepa-1 only when the cells are treated with the xenobiotics, while the factor is undetectable in the nuclei of a 3-methylcholanthrene-treated mutant of Hepa-1 with defective function of a xenobiotic receptor. In addition, the nuclear factor bound to the XRE in the gel was found to be associated with [3H]TCDD when the cells were treated with it, suggesting that the xenobiotic receptor is at least a component of the DNA-binding factor. The cytoplasmic fraction from nontreated Hepa-1 cells also contains the factor as a cryptic form and prominently reveals its DNA-binding activity by incubation with 3-methylcholanthrene in vitro. These results not only suggest the involvement of the XRE-binding factor in transcriptional activation via XREs but also provide evidence that the binding of ligands to the preexisting factor in a cryptic form induces its XRE-binding activity, which is probably followed by its translocation from cytoplasm to nucleus.
More Related Videos
Related Concept Videos
Cell Specific Gene Expression
Regulation of Nuclear Protein Sorting
Protein Import into the Peroxisomes
Peroxisomal Protein Import:
Peroxisomes lack the genetic machinery required to code for their own proteins. Hence, most peroxisomal membrane, lumenal and transmembrane proteins are synthesized in the cytoplasm or ER and transported to the peroxisome...
General Transcription Factors
Transducer Mechanism: Nuclear Receptors
About 48 different soluble family members of nuclear receptors are identified that can be divided into two main classes:
Pharmacogenetics of Phase I Enzymes: Cytochrome P450 Isozymes

