SREBP1A/1C/2 (SREBF1A/1C/2), together with NF-Y, bind and transactivate the promoter of the HMGCS1 gene (Maeda et al. 1998, Pai et al. 1998, Amemiya-Kudo et al. 2002, Reed et al. 2008). SREBP1A and SREBP2 activate HMGCS1 equally (Pai et al. 1998).
3-hydroxy-3-methylglutaryl Coenzyme A synthase (HMG-CoA synthase) catalyzes the condensation of acetyl CoA with acetoacetyl CoA to produce HMG-CoA. There are two forms of this enzyme, cytosolic and mitochondrial. The cytosolic form is ubiquitous in the body and is involved in cholesterol biosynthesis and synthesis of other isoprenoid products. The mitochondrial form, found solely in the liver and kidney, is involved in the ketogenic pathway.