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Additional protein factors play a role in the formation of VDR/RXR complexes on vitamin D response elements
Author(s) -
Zierold Claudia,
DeLuca H. F.
Publication year - 1998
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/(sici)1097-4644(19981215)71:4<515::aid-jcb6>3.0.co;2-c
Subject(s) - calcitriol receptor , retinoid x receptor , transcription factor , microbiology and biotechnology , chemistry , retinoic acid , nuclear receptor , receptor , biology , biochemistry , gene
The vitamin D receptor (VDR) elicits a transcriptional response to 1,25‐dihydroxyvitamin D 3 by binding to specific response elements (VDRE) in the promoter of target genes. Retinoic X receptor (RXR) is required for formation of the VDR‐VDRE complex when VDR is supplied at physiologic concentrations. When porcine intestinal nuclear extract is used as a source of VDR, two distinct complexes are always observed with native gel electrophoresis. Both complexes contain VDR and RXR. We now show that the faster‐migrating complex requires another heretofore unknown nuclear factor for its formation. In addition, we provide evidence that the formation of the slower‐migrating complex is enhanced by transcription factor IIB (TFIIB). Using ligand binding assays, we determined that both complexes contain the same ratio of VDR to VDRE. Using RXR subtype‐specific antibodies in gel shift assays, we show that the complexes contain more than one RXR subtype. Therefore, the present results demonstrate VDR‐RXR‐VDRE complexes formed with pig intestinal nuclear extracts contain other proteins and that the complexes formed between VDR and VDRE are not simply heterodimers of VDR and RXR. J. Cell. Biochem. 71:515–523, 1998. © 1998 Wiley‐Liss, Inc.