From Wikipedia, the free encyclopedia
HMG-CoA synthase is an enzyme which catalyzes the reaction where Acetyl-CoA condenses with acetoacetyl-CoA to form 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA).
There are two different forms of the enzyme; in humans the cytosolic form has only 60.6% amino acid identity with the mitochondrial form of the enzyme.
HMG-CoA synthase reaction
[edit] Cytosolic
The cytosolic enzymes has a key role in the production of cholesterol and other isoprenoids:
[edit] Mitochondrial
The mitochondrial form is used for the production of ketone bodies:
[edit] Regulation
The gene for the mitochondrial form of the enzyme has three sterol regulatory elements in the 5' flanking region [1]. These elements are responsible for decreased transcription of the message responsible for enzyme synthesis when dietary cholesterol is high in animals: the same is observed for 3-hydroxy-3-methylglutaryl-CoA and the low density lipoprotein receptor.
[edit] External links
[edit] References
- ^ Goldstein J.L., Brown M.S. (1990) Regulation of the mevalonate pathway. Nature 343, 425-430
