PROSITE documentation PDOC00942
Hydroxymethylglutaryl-coenzyme A synthase active site


Hydroxymethylglutaryl-coenzyme A synthase (EC (HMG-CoA synthase) catalyzes the condensation of acetyl-CoA with acetoacetyl-CoA to produce HMG-CoA and CoA [1].

In vertebrates there are two isozymes located in different subcellular compartments: a cytosolic form which is the starting point of the mevalonate pathway which leads to cholesterol and other sterolic and isoprenoid compounds and a mitochondrial form responsible for ketone body biosynthesis. HMG-CoA is also found in other eukaryotes such as insect, plants and fungi.

A cysteine is known to act as the catalytic nucleophile in the first step of the reaction, the acetylation of the enzyme by acetyl-CoA. We have used the conserved region around this active site residue as a signature pattern.

Last update:

April 2003 / Text revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

HMG_COA_SYNTHASE, PS01226; Hydroxymethylglutaryl-coenzyme A synthase active site  (PATTERN)


1AuthorsRokosz L.L. Boulton D.A. Butkiewicz E.A. Sanyal G. Cueto M.A. Lachance P.A. Hermes J.D.
TitleHuman cytoplasmic 3-hydroxy-3-methylglutaryl coenzyme A synthase: expression, purification, and characterization of recombinant wild-type and Cys129 mutant enzymes.
SourceArch. Biochem. Biophys. 312:1-13(1994).
PubMed ID7913309

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