Constitutive Androstane Receptor-2 (CAR-2; NR1I3i2)
| Product Family | Product Number | Product Description | Technical Manual |
| IB0092 CAR-2 (NR1I3i2) |
IB00921-32 | Human CAR-2 Reporter Assay System, 3 x 32 assays in 96-well format | Technical Manual |
| IB00921 | Human CAR-2 Reporter Assay System, 1 x 96-well format assays | Technical Manual | |
| IB00922 | Human CAR-2 Reporter Assay System, 1 x 384-well format assays |
Constitutive Androstane Receptor-2 Assay Kits 
This Constitutive Androstane Receptor-2 (CAR-2) assay kit is an all-inclusive CAR-2 reporter assay system that includes, in addition to CAR-2 Reporter Cells, two optimized media for use during cell culture and (optionally) in diluting the test samples, a reference agonist, Luciferase Detection Reagent, a cell culture-ready assay plate, and a detailed protocol.
CAR-2 Reporter Cells are prepared using INDIGO’s proprietary CryoMite™ process. This cryo-preservation method yields high cell viability post-thaw, and provides the convenience of immediately dispensing healthy, division-competent reporter cells into assay plates. There is no need for intermediate spin-and-wash steps, viability determinations, or cell titer adjustments.
INDIGO’s assay kits feature a luciferase detection reagent specially formulated to provide stable light emission between 5 and 90+ minutes after initiating the luciferase reaction. Incorporating a 5-minute reaction-rest period ensures that light emission profiles attain maximal stability, thereby allowing assay plates to be processed in batch. By doing so, the signal output from all sample wells, from one plate to the next, may be directly compared within an experimental set.
Kits are offered in different assay formats to accommodate researchers' needs: 3x 32 and 1x 96 assay formats for screening small numbers of test compounds, as well as custom bulk reagents for HTS applications.
Bulk assay reagents can be custom manufactured to accommodate any scale of HTS. Please inquire.
CAR-2 assay kit also available in: Mouse
Constitutive Androstane Receptor-2 Assay Services
The primary application of INDIGO’s cell-based nuclear receptor assays are to quantitatively assess the bioactivity of a test compound as an agonist (activator) or antagonist (inhibition of an agonist response) of a given receptor. Service assays include a positive control reference compound and ‘vehicle’ control for every experiment. A formal study report and all data files are provided to the client upon completion of the study. To receive a quote for your proposed study, complete & submit the online “Request a Quote” form or contact an INDIGO Customer Service Representative to discuss your desired study parameters.
CAR-2 Service Assays: Human, Mouse
Constitutive Androstane Receptor-2 Background
The constitutive androstane receptor (CAR), also known as NR1I3 (nuclear receptor subfamily 1, group I, member 3), is a nuclear hormone receptor with activity similar to that seen in other steroid receptors such as estrogen or progesterone but more similar in form to PPAR, LXR and RXR. CAR functions differently from other steroid receptors and its activity is still being elucidated. It is known to act in concert with PXR to detoxify xenobiotics. CAR is encoded by the NR1I3 gene. This gene encodes 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. Multiple transcript variants encoding different isoforms have been found for this gene. CAR exists as three predominant splice variants in humans depicted as CAR-1, CAR-2 and CAR-3. Each has unique biological properties. These splice variants do not exist in rat and mouse.
Unlike CAR-1, CAR-2 is not constitutively active, showing ligand-dependent activation of reporter genes linked to genetic response elements derived from CYP2B6 or CYP3A4 promoters. Diethylhexyl phthalate (DEHP) is a strong agonist of CAR-2 but has no activity toward CAR-1 or CAR-3.
It is noteworthy, and a source of experimental confusion, that a number of xenobiotics characterized as activators of human CAR (including phenobarbital) actually modulate the receptor's activity via indirect mechanisms. In other words, such chemicals do not directly bind to CAR; rather, they impact the activity of upstream regulatory mechanisms that impinge on CAR activity. Hybrid nuclear receptors in which the native N-terminal DNA binding domain (DBD) has been substituted with the GAL4 DBD, such as is used in this reporter assay system, likely will not be responsive to chemical modulators that act through indirect mechanisms.
The principle application of this assay product is in the screening of test samples to quantify functional activities, either agonist or antagonist, that they may exert against the human constitutive androstane receptor.
Synonyms: Constitutive Androstane Receptor-2, CAR-2, NR1I3i2
Constitutive Androstane Receptor-2 Assay Data
Constitutive Androstane Receptor-2 Assay Research Areas
Xenobiotic Metabolism; Bile Acid and Xenobiotic Metabolism; Toxicology; NAFLD/NASH; Drug-Nutrient Interaction