The retinoid X receptor (RXR)[1] is a type of nuclear receptor that is activated by 9-cis retinoic acid, which is discussed controversially to be of endogenous relevance,[2][3] and 9-cis-13,14-dihydro-retinoic acid, which is likely to be the major endogenous mammalian RXR-selective agonist.[4] There are three retinoic X receptors (RXR): RXR-alpha, RXR-beta, and RXR-gamma, encoded by the RXRA, RXRB, RXRG genes, respectively.
As with other type II nuclear receptors, the RXR heterodimer in the absence of ligand is bound to hormone response elements complexed with corepressor protein. Binding of agonist ligands to RXR results in dissociation of corepressor and recruitment of coactivator protein, which, in turn, promotes transcription of the downstream target gene into mRNA and eventually protein.
