The steroid receptor superfamily acts through direct association with DNA sequences known as hormone response elements (HREs) and binds DNA as either homo- or heterodimers. The promiscuous mediator of heterodimerization, RXR, is the receptor for 9-cis retinoic acid, and dimerizes with VDR, TR, PPAR, and several novel receptors including LXR (also referred to as RLD-1) and FXR. FXR and LXR fall into a category of proteins termed â€orphan receptorsâ€ because of their lack of a defined function, and in the case of LXR, the lack of a defined ligand. FXR has been shown to bind a class of lipid molecules called farnesoids. LXR/RXR heterodimers have highest affinity for DR-4 DNA elements while FXR/RXR heterodimers bind IR-1 elements. Both LXR/RXR and FXR/RXR heterodimers retain their responsiveness to 9-cis retinoic acid.
Subcellular location: Nucleus
Synonyms: BAR, FXR, HRR1, HRR-1, PFIC5, RIP14, Bile acid receptor, Farnesoid X-activated receptor, Farnesol receptor HRR-1, Nuclear receptor subfamily 1 group H member 4, Retinoid X receptor-interacting protein 14, RXR-interacting protein 14, NR1H4