HMG-CoA synthase

3-hydroxy-3-methylglutaryl-Coenzyme A synthase 1 (soluble)
Identifiers
Symbol	HMGCS1
Alt. Symbols	HMGCS
Entrez	3157
HUGO	5007
OMIM	142940
RefSeq	NM_002130
UniProt	Q01581
Other data
EC number	2.3.3.10
Locus	Chr. 5 p14-p13

3-hydroxy-3-methylglutaryl-Coenzyme A synthase 2 (mitochondrial)
Identifiers
Symbol	HMGCS2
Entrez	3158
HUGO	5008
OMIM	600234
RefSeq	NM_005518
UniProt	P54868
Other data
Locus	Chr. 1 p13-p12

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 from of the enzyme.

HMG-CoA synthase reaction

The cytosolic enzymes has a key role in the production of cholesterol and other isoprenoids:

Mevalonate pathway

The mitochondrial form is used for the production of ketone bodies:

File:Ketogenesis.png

Ketogenesis

Regulation

The gene for the mitochondrial form of the enzyme has three sterol regulatory elements in the 5' flanking region . 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.

External links

• MeSH HMG-CoA+synthase