Liver X receptor beta (LXR-β) is a member of thenuclear receptor family oftranscription factors. LXR-β is encoded by theNR1H2 gene (nuclear receptor subfamily 1, group H, member 2).[5]
Theliver X receptors (LXRs) were originally identified asorphan members of the nuclear receptor superfamily because their ligands were unknown. Like other receptors in the family, LXRs heterodimerize withretinoid X receptor and bind to specificresponse elements (LXREs) characterized bydirect repeats separated by 4 nucleotides. Two genes, alpha (LXRA) and beta, are known to encode LXR proteins.[5][6]
Crystal structure of human liver X receptor β(LXRβ) forming heterodimer with its partner retinoid X receptor α(RXRα) on its cognate element, an AGGTCA direct repeat spaced by 4 nt shows an extended X-shaped arrangement, with DNA- and ligand-binding domains crossed. The LXRβ core binds DNA via canonical contacts and auxiliary DNA contacts that enhance affinity for the response element.[7]
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^Lou X, Toresson G, Benod C, Suh JH, Philips KJ, Webb P, Gustafsson JA (Mar 2014). "Structure of the retinoid X receptor α-liver X receptor β (RXRα-LXRβ) heterodimer on DNA".Nature Structural & Molecular Biology.21 (3):277–81.doi:10.1038/nsmb.2778.PMID24561505.S2CID23226682.
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Hoerer S, Schmid A, Heckel A, Budzinski RM, Nar H (Dec 2003). "Crystal structure of the human liver X receptor beta ligand-binding domain in complex with a synthetic agonist".Journal of Molecular Biology.334 (5):853–61.doi:10.1016/j.jmb.2003.10.033.PMID14643652.
