Three known isoforms of SREBP (sterol regulatory element binding protein) transcription factors have been characterized: SREBP-1a, SREBP-1c, and SREBP-2. SREBP-1c acts primarily to activate genes required for fatty acid synthesis, such as acetyl CoA carboxylase, fatty acid synthase, and long chain fatty acid elongase. In addition, SREBP-1c may also contribute to the regulation of glucose uptake and synthesis through induction of glucokinase. SREBP-1c has important clinical implications in the treatment of many diseases including obesity, diabetes mellitus, insulin resistance, and non-alcoholic fatty liver disease (NAFLD). Cayman’s SREBP-1 Transcription Factor Assay is a non-radioactive, sensitive method for detecting specific transcription factor DNA binding activity. SREBP-1 contained in nuclear extracts and whole cell lysates binds to a dsDNA SREBP response element immobilized to the wells of a 96-well plate. SREBP-1 is detected by addition of a specific primary antibody directed against SREBP-1. A secondary antibody conjugated to HRP is used to provide a sensitive colorimetric readout at 450 nm.

Horton, J.D., Shah, N.A., Warrington, J.A., et al. Combined analysis of oligonucleotide microarray data from transgenic and knockout mice identifies direct SREBP target genes. Proc Natl Acad Sci USA 100(21) 12027-12032 (2003).

Shimano, H. SREBP-1c and TFE3, energy transcription factors that regulate hepatic insulin signaling. J Mol Med 85 437-444 (2007).

Shimano, H., Horton, J.D., Shimomura, I., et al. Isoform 1c of sterol regulatory element binding protein is less active than isoform 1a in livers of transgenic mice and in cultured cells. J Clin Invest 99(5) 846-854 (1997).

Espenshade, P.J., and Hughes, A.L. Regulation of sterol synthesis in eukaryotes. Annu Rev Genet 41 401-427 (2007).

Ahmed, M.H., and Byrne, C.D. Modulation of sterol regulatory element binding proteins (SREBPs) as potential treatments for non-alcoholic fatty liver disease (NAFLD). Drug Discov Today 12(17/18) 740-747 (2007).

Eberlé, D., Hegarty, B., Bossard, P., et al. SREBP transcription factors: Master regulators of lipid homeostasis. Biochimie 86 839-848 (2004).

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