| Purification and Quality Control | The His-tag recombinant protein is purified by affinity chromatography in combination with FPLC columns. The purified PXR-LBD is greater than 95% homogeneous based on SDS-PAGE analysis. |
| Unit Definition (Activity) | 1 unit equals 1 nanogram of purified protein. |
| Applications | PXR-LBD can be used for ligand binding assays. For Research Use Only. |
| Formulation and Storage | The protein is in 20mM Tris-HCl pH7.9,100mM NaCl, 0.2mM EDTA, 1mM DTT and 20% glycerol. Stored at -70°C before use. Avoid repeated freeze thaw cycles. |
| Synonym | NR1I2; BXR; ONR1; PAR; PAR1; PAR2; PARq; PRR;SAR and SXR. |
| Protein Sequence | LGVQGLTEEQ RMMIRELMDA QMKTFDTTFS HFKNFRLPGV LSSGCELPES LQAPSREEAA
KWSQVRKDLC SLKVSLQLRG EDGSVWNYKP PADSGGKEIF SLLPHMADMS TYMFKGIISF
AKVISYFRDL PIEDQISLLK GAAFELCQLR FNTVFNAETG TWECGRLSYC LEDTAGGFQQ
LLLEPMLKFH YMLKKLQLHE EEYVLMQAIS LFSPDRPGVL QHRVVDQLQE QFAITLKSYI
ECNRPQPAHR FLFLKIMAML TELRSINAQH TQRLLRIQDI HPFATPLMQE LFGITGS |
| Background | The nuclear pregnane X receptor (PXR; NR1I2) is an important component of the body’s adaptive defense mechanism against toxic substances including foreign chemicals (xenobiotics) (1, 2). PXR is activated by a large number of endogenous and exogenous chemicals including steroids, antibiotics, antimycotics, bile acids, and the herbal antidepressant St. John’s wort (3-7). PXR is known to regulate the expression of several additional genes encoding proteins involved in xenobiotic metabolism, including multidrug resistance protein 1 (MDR1) (8,9), multidrug resistance-associated protein 2 (MRP2) (10,11), and organic anion transporter polypeptide 2 (12). Elucidation of the three-dimensional structure of the PXR ligand binding domain revealed that it has a large, spherical ligand binding cavity that allows it to interact with a wide range of hydrophobic chemicals. Thus, unlike other nuclear receptors that interact selectively with their physiological ligands, PXR serves as a generalized sensor of hydrophobic toxins. PXR binds as a heterodimer with the 9-cis retinoic acid receptor (NR2B) to DNA response elements in the regulatory regions of cytochrome P450 3A monooxygenase genes and a number of other genes involved in the metabolism and elimination of xenobiotics from the body. |
| References | 1. Waxman DJ (1999) Arch Biochem Biophys 369: 11-23
2. Honkakoski P and Negishi M (2000) Biochem J 347: 321-337
3. Bertilsson G, et al. (1998) Proc Natl Acad Sci USA 95: 12208-12213
4. Blumberg B, et al. (1998) Genes Dev 12: 3195-3205
5. Kliewer SA, et al. (1998) Cell 92: 73-82
6. Lehmann JM, et al. (1998) J Clin Invest 102: 1016-1023
7. Moore LB, et al. (2000) Proc Natl Acad Sci USA 97: 7500-7502
8. Geick A, et al. (2001) J Biol Chem 276: 14581-14587
9. Synold TW, et al. (2001) Nat Med 7: 584-590
10. Dussault I, et al. (2001) J Biol Chem 276: 33309-33312
11. Kast HR, et al. (2002) J Biol Chem 277: 2908-2915
12. Staudinger JL, et al. (2001) Proc Natl Acad Sci USA 98: 3369-3374 |
| Image of SDS-PAGE /Western-blot |  |
