Constitutive androstane receptor

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Nuclear receptor subfamily 1, group I, member 3
Protein NR1I3 PDB 1xv9.png
PDB rendering based on 1xv9.
Available structures
PDB Ortholog search: PDBe, RCSB
Symbols NR1I3 ; CAR; CAR1; MB67
External IDs OMIM603881 MGI1346307 HomoloGene3759 IUPHAR: NR1I3 ChEMBL: 5503 GeneCards: NR1I3 Gene
RNA expression pattern
PBB GE NR1I3 207007 at tn.png
More reference expression data
Species Human Mouse
Entrez 9970 12355
Ensembl ENSG00000143257 ENSMUSG00000005677
UniProt Q14994 O35627
RefSeq (mRNA) NM_001077469 NM_001243062
RefSeq (protein) NP_001070937 NP_001229991
Location (UCSC) Chr 1:
161.2 – 161.21 Mb
Chr 1:
171.21 – 171.22 Mb
PubMed search [1] [2]

The constitutive androstane receptor (CAR) also known as nuclear receptor subfamily 1, group I, member 3 is a protein that in humans is encoded by the NR1I3 gene.[1] CAR is a member of the nuclear receptor superfamily and along with PXR functions as a sensor of endobiotic and xenobiotic substances and in response upregulates the expression of proteins responsible for the metabolism and excretion of these substances.[2] Hence CAR (and PXR) are important in the detoxification of foreign substances such as drugs.


CAR is a member of the nuclear receptor superfamily, and is a key regulator of xenobiotic and endobiotic metabolism. The protein binds to DNA as a monomer or a heterodimer with the retinoid X receptor and regulates the transcription of target genes involved in drug metabolism and bilirubin clearance, such as cytochrome P450 family members. Unlike most nuclear receptors, this transcriptional regulator is constitutively active in the absence of ligand but is regulated by both agonists and inverse agonists. Ligand binding results in translocation of this protein to the nucleus, where it activates or represses target gene transcription. These ligands include bilirubin, a variety of foreign compounds, steroid hormones, and prescription drugs.[3]


  1. ^ Baes M, Gulick T, Choi HS, Martinoli MG, Simha D, Moore DD (March 1994). "A new orphan member of the nuclear hormone receptor superfamily that interacts with a subset of retinoic acid response elements". Mol. Cell. Biol. 14 (3): 1544–52. PMC 358513. PMID 8114692. 
  2. ^ Wada T, Gao J, Xie W (August 2009). "PXR and CAR in energy metabolism". Trends Endocrinol. Metab. 20 (6): 273–9. doi:10.1016/j.tem.2009.03.003. PMID 19595610. 
  3. ^ "Entrez Gene: NR1I3 nuclear receptor subfamily 1, group I, member 3". 

Further reading[edit]

External links[edit]

This article incorporates text from the United States National Library of Medicine, which is in the public domain.