Antigen: human SREBP-2 amino acids 455-469 (SPLLDDAKVKDEPDS) · Host: rabbit · Application(s): WB and ICC; other applications not tested · SREBPs, including SREBP-1a, SREBP-1c, and SREBP-2, constitute a family of basic helix-loop-helix (bHLH) transcription factors that play a critical role in lipid homeostasis by regulating genes involved in cholesterol and fatty acid metabolism.¹ Each SREBP consists of three domains, including an amino-terminal transcription factor domain of ~480 amino acids, a middle hydrophobic region of ~80 amino acids containing two hydrophobic transmembrane segments, and a carboxy-terminal regulatory domain of ~590 amino acids.¹ SREBP-2 regulates cholesterol synthesis by activating the transcription of genes for HMG-CoA reductase and other enzymes of the cholesterol synthetic pathway.² SREBP-2 is ubiquitously detected in various tissues.³ Under basal conditions SREBP is bound to ER membranes as a glycosylated precursor protein. Upon cholesterol depletion, the protein is cleaved to its active forms (about 50-68 kDa) and translocated into the nucleus to stimulate transcription of genes involved in the uptake and synthesis of cholesterol.⁴ Cayman’s SREBP-2 polyclonal antibody detects both precursor and active forms of the protein in tissues and cells such as liver, brown fat, testis, Hep-G₂ cells, and human fibroblast. The apparent molecular weight on SDS-PAGE may be higher than the calculated molecular weight (about 126 kDa) due to glycosylation of the protein.⁵

1 Brown, M.S., and Goldstein, J.L. The SREBP pathway: Regulation of cholesterol metabolism by proteolysis of a membrane-bound transcription factor. Cell 89 331-340 (1997).

2 Sakai, J., Nohturfft, A., Goldstein, J.L., et al. Cleavage of sterol regulatory element-binding proteins (SREBPs) at site-1 requires interaction with SREBP cleavage-activating protein. Evidence from in vivo competition studies. J Biol Chem 273(10) 5785-5793 (1998).

3 Iizuka, K., Bruick, R.K., Liang, G., et al. Deficiency of carbohydrate response element-binding protein (ChREBP) reduces lipogenesis as well as glycolysis. Proc Natl Acad Sci USA 101(19) 7281-7286 (2004).

4 Smith, L.H., Petrie, M.S., Morrow, J.D., et al. 7The sterol response element binding protein regulates cyclooxygenase-2 gene expression in endothelial cells. J Lipid Res 46 862-871 (2005).

5 Hua, X., Sakai, J., Ho, Y.K., et al. Hairpin orientation of sterol regulatory element-binding protein-2 in cell membranes as determined by protease protection. J Biol Chem 270(49) 29422-29427 (1995).

Brown, M.S., and Goldstein, J.L. The SREBP pathway: Regulation of cholesterol metabolism by proteolysis of a membrane-bound transcription factor. Cell 89 331-340 (1997).

Hua, X., Sakai, J., Ho, Y.K., et al. Hairpin orientation of sterol regulatory element-binding protein-2 in cell membranes as determined by protease protection. J Biol Chem 270(49) 29422-29427 (1995).

Sakai, J., Nohturfft, A., Goldstein, J.L., et al. Cleavage of sterol regulatory element-binding proteins (SREBPs) at site-1 requires interaction with SREBP cleavage-activating protein. Evidence from in vivo competition studies. J Biol Chem 273(10) 5785-5793 (1998).

Iizuka, K., Bruick, R.K., Liang, G., et al. Deficiency of carbohydrate response element-binding protein (ChREBP) reduces lipogenesis as well as glycolysis. Proc Natl Acad Sci USA 101(19) 7281-7286 (2004).

Smith, L.H., Petrie, M.S., Morrow, J.D., et al. 7The sterol response element binding protein regulates cyclooxygenase-2 gene expression in endothelial cells. J Lipid Res 46 862-871 (2005).

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