Liver X receptor beta (LXR-β) is a member of the

nuclear receptor In the field of molecular biology, nuclear receptors are a class of proteins responsible for sensing steroids, thyroid hormones, vitamins, and certain other molecules. These intracellular receptors work with other proteins to regulate the ex ...

family of

transcription factors In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. The fun ...

. LXR-β is encoded by the gene (nuclear receptor subfamily 1, group H, member 2).

Function

The

liver X receptor The liver X receptor (LXR) is a member of the nuclear receptor family of transcription factors and is closely related to nuclear receptors such as the PPARs, FXR and RXR. Liver X receptors (LXRs) are important regulators of cholesterol, fatt ...

s (LXRs) were originally identified as

orphan An orphan is a child whose parents have died, are unknown, or have permanently abandoned them. It can also refer to a child who has lost only one parent, as the Hebrew language, Hebrew translation, for example, is "fatherless". In some languages ...

members of the nuclear receptor superfamily because their ligands were unknown. Like other receptors in the family, LXRs heterodimerize with

retinoid X receptor The retinoid X receptor (RXR) is a type of nuclear receptor that is activated by 9-cis retinoic acid, which is discussed controversially to be of endogenous relevance, and 9-''cis''-13,14-dihydroretinoic acid, which may be an endogenous mamma ...

and bind to specific

response element ''Response elements'' are short sequences of DNA within a gene promoter or enhancer region that are able to bind specific transcription factors and regulate transcription of genes. Under conditions of stress, a transcription activator protein bi ...

s (LXREs) characterized by

direct repeat Direct repeats are a type of genetic sequence that consists of two or more repeats of a specific sequence. In other words, the direct repeats are nucleotide sequences present in multiple copies in the genome. Generally, a direct repeat occurs when a ...

s separated by 4 nucleotides. Two genes, alpha ( LXRA) and beta, are known to encode LXR proteins.

Structure

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.

Interactions

Liver X receptor beta has been shown to interact with

NCOA6 Nuclear receptor coactivator 6 is a protein that in humans is encoded by the ''NCOA6'' gene. Function The protein encoded by this gene is a transcriptional coactivator that can interact with nuclear hormone receptors to enhance their transc ...

and

Retinoid X receptor alpha Retinoid X receptor alpha (RXR-alpha), also known as NR2B1 (nuclear receptor subfamily 2, group B, member 1) is a nuclear receptor that in humans is encoded by the ''RXRA'' gene. Function Retinoid X receptors (RXRs) and retinoic acid receptors ...

Function

Structure

Interactions

References

Further reading