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DNA binding specificity and function of retinoid X receptor alpha
J S Subauste1, R W Katz, R J Koenig
1Division of Endocrinology and Metabolism, University of Michigan Medical Center, Ann Arbor 48109-0678.
The Journal of Biological Chemistry
|December 2, 1994
Summary
Researchers identified the highest affinity binding site for Retinoid X receptors (RXRs) as GGGGTCA, surpassing the previously known AGGTCA sequence. This discovery enhances understanding of RXR transcriptional regulation.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Retinoid X receptors (RXRs) are ligand-inducible transcription factors belonging to the erbA superfamily.
- RXRs bind to the hexameric DNA sequence AGGTCA and activate transcription upon binding to direct repeats with a one-base pair spacer in the presence of 9-cis-retinoic acid.
Purpose of the Study:
- To determine if AGGTCA is the highest affinity binding site for RXRs.
- To identify the optimal DNA sequence for RXR binding and transcriptional activation.
Main Methods:
- Electrophoretic mobility shift assay combined with polymerase chain reaction to isolate high-affinity binding sequences from random DNA pools.
- Mutational analysis and DNA footprinting to confirm the identified sequence.
Main Results:
- The seven-base pair sequence GGGGTCA was identified as the highest affinity RXR binding site.
- Direct repeats of GGGGTCA function as a more potent response element than direct repeats of AGGTCA.
Conclusions:
- The GGGGTCA sequence represents the optimal DNA binding motif for Retinoid X receptors.
- This finding refines our understanding of RXR-mediated transcriptional regulation and response element design.