Retinoid X receptor

Retinoid X receptor (RXR) is a type of nuclear receptor that is activated by retinoids, which are metabolites of Vitamin A. RXRs play a crucial role in the regulation of gene expression, controlling cellular differentiation, development, and metabolism.

Function

RXRs function as transcription factors, binding to specific sequences of DNA in the promoter region of target genes. They regulate gene expression by interacting with other proteins, including other types of nuclear receptors. RXRs can form homodimers with themselves or heterodimers with other nuclear receptors, such as thyroid hormone receptors, vitamin D receptors, and peroxisome proliferator-activated receptors.

Structure

Like other nuclear receptors, RXRs have a modular structure with several functional domains. The N-terminal domain (A/B) contains a ligand-independent activation function, the DNA-binding domain (C) recognizes and binds to specific DNA sequences, the hinge region (D) allows flexibility, and the ligand-binding domain (E/F) binds to retinoids and contains a ligand-dependent activation function.

Ligands

The natural ligands for RXRs are 9-cis retinoic acid and all-trans retinoic acid, both of which are metabolites of vitamin A. Synthetic ligands, known as retinoid X receptor agonists, have also been developed for therapeutic use.

Clinical significance

RXRs are involved in many physiological processes and their dysfunction has been implicated in a variety of diseases, including cancer, diabetes, atherosclerosis, and neurodegenerative diseases. RXR agonists are being investigated as potential treatments for these and other conditions.

See also

• Retinoic acid receptor
• Retinoid
• Nuclear receptor