| Purification and Quality Control | The His-tag recombinant protein is purified by affinity chromatography in combination with FPLC columns. The purified LXR-beta is greater than 95% 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-beta 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 | NR1H2; LXR-b; LXRB; NER; NER-I; RIP15 and UNR. | | Protein Sequence | MSSPTTSSLD TPLPGNGPPQ PGAPSSSPTV KEEGPEPWPG GPDPDVPGTD EASSACSTDW
VIPDPEEEPE RKRKKGPAPK MLGHELCRVC GDKASGFHYN VLSCEGCKGF FRRSVVRGGA
RRYACRGGGT CQMDAFMRRK CQQCRLRKCK EAGMREQCVL SEEQIRKKKI RKQQQQESQS
QSQSPVGPQG SSSSASGPGA SPGGSEAGSQ GSGEGEGVQL TAAQELMIQQ LVAAQLQCNK
RSFSDQPKVT PWPLGADPQS RDARQQRFAH FTELAIISVQ EIVDFAKQVP GFLQLGREDQ
IALLKASTIE IMLLETARRY NHETECITFL KDFTYSKDDF HRAGLQVEFI NPIFEFSRAM
RRLGLDDAEY ALLIAINIFS ADRPNVQEPG RVEALQQPYV EALLSYTRIK RPQDQLRFPR
MLMKLVSLRT LSSVHSEQVF ALRLQDKKLP PLLSEIWDVH E | | 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). LXRβ expressed in livers of LXRα knockout mice does not compensate for the loss of LXRα (11). In addition, LXRβ, but not LXRα, is also able to activate transcription of a reporter gene, which contains a specific direct repeat separated by 1 bp (DR1) element in the promoter, suggesting that LXRβ may have different biological functions (12). | | 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
12. Feltkamp et al., (1999) J. Biol. Chem. 274, 10421-10429 |
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