| Purification and Quality Control | The His-tag recombinant protein is purified by affinity chromatography in combination with FPLC columns. The purified LXR-alpha is greater than 90% homogeneous based on SDS-PAGE analysis. | | Unit Definition (Activity) | 1 unit equals 1 nanogram of purified protein. 20 units are sufficient for a gel-mobility shift assay and 100 units are sufficient for a protein-protein interaction assay. | | Applications | LXR has been applied in DNA and protein-protein interactions assays. | | 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 | NR1H3; LXRA and RLD-1. | | Protein Sequence | SLWLGAPVPD IPPDSAVELW KPGAQDASSQ AQGGSSCILR EEARMPHSAG GTAGVGLEAA
EPTALLTRAE PPSEPTEIRP QKRKKGPAPK MLGNELCSVC GDKASGFHYN VLSCEGCKGF
FRRSVIKGAH YICHSGGHCP MDTYMRRKCQ ECRLRKCRQA GMREECVLSE EQIRLKKLKR
QEEEQAHATS LPPRRSSPPQ ILPQLSPEQL GMIEKLVAAQ QQCNRRSFSD RLRVTPWPMA
PDPHSREARQ QRFAHFTELA IVSVQEIVDF AKQLPGFLQL SREDQIALLK TSAIEVMLLE
TSRRYNPGSE SITFLKDFSY NREDFAKAGL QVEFINPIFE FSRAMNELQL NDAEFALLIA
ISIFSADRPN VQDQLQVERL QHTYVEALHA YVSIHHPHDR LMFPRMLMKL VSLRTLSSVH
SEQVFALRLQ DKKLPPLLSE IWDVHE | | Background | Liver X receptors (LXRs) are nuclear receptors that regulate the metabolism of cholesterol and bile acids (1). There are two subtypes of LXRs, LXRα and LXRβ. LXRβ is preferentially expressed in liver, small intestine, kidney and spleen (2, 3). In contrast, LXRα expression is ubiquitous (4). The genomic structure and the promoter regions of the two LXR genes contain specific regulatory sites, which suggest that LXRs may have physiological roles in the immune system (5). Like other nuclear receptors, LXRs heterodimerize with retinoid X receptor (RXR) for function (1). LXRs are activated by naturally occurring oxysterols and regulate the expression of target genes (6-8), including ATP binding cassette transporter 1 (ABC1), ATP binding cassette transporter 8 (ABC8) and cholesterol ester transfer protein (CETP) (9-10). LXRα is thought to play a major role in the control of cholesterol catabolism by stimulating the expression of cholesterol 7 alpha-hydroxylase (CYP7A1), the rate limiting enzyme of bile acid synthesis (11). | | References | 1. Peet et al., (1998) Curr. Opin. Gent. Dev. 8, 571-575
2. Willy et al., (1995) Genes Dev. 9, 1033-1045
3. Apfel et al., (1994) Mol. Cell. Biol. 14, 7025-7035
4. Song et al., (1994) Proc. Natl. Acad. Sci. 91, 10809-10813
5. Alberti et al., (2000) Gene 243, 93-103
6. Janowski et al., (1996) Nature 383, 728-731
7. Lehmann et al., (1997) J. Biol. Chem. 272, 3137-3140
8. Janowski et al., (1999) Proc. Natl. Acad. Sci. 96, 266-271
9. Luo et al., (2000) J. Clin. Invest. 105, 513-520
10. Venkateswaran et al., (2000) J. Biol. Chem. 275, 14700-14707
11. Peet et al., (1998) Cell 93, 693-704 |
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