Millisecond to microsecond time scale dynamics of the retinoid X and retinoic acid receptor DNA-binding domains and dimeric complex formation

The 9-cis retinoic acid receptor (RXR) and the all-trans retinoic acid receptor (RAR) are members of a family of ligand inducible transcription factors. Nuclear receptors belonging to the Class II sub-family, RXR and RAR both bind to DNA as dimers, on tandem repeats of a hexamer motif separated by a variable spacer. The DNA-binding domains of RXR and RAR have zinc-coordinating loop regions that exhibit millisecond to microsecond time scale dynamics. A functional role for the dynamics is suggested by the close association between regions of conformational exchange and dimer interfaces.