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Acetyl-CoA carboxylase 2 also known as ACC-beta or ACC2 is an
enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...
that in humans is encoded by the ''ACACB''
gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
.


Function

Acetyl-CoA carboxylase Acetyl-CoA carboxylase (ACC) is a biotin-dependent enzyme () that catalyzes the irreversible carboxylation of acetyl-CoA to produce malonyl-CoA through its two catalytic activities, biotin carboxylase (BC) and carboxyltransferase (CT). ACC ...
(ACC) is a complex multifunctional enzyme system. ACC is a
biotin Biotin (also known as vitamin B7 or vitamin H) is one of the B vitamins. It is involved in a wide range of metabolic processes, both in humans and in other organisms, primarily related to the utilization of fats, carbohydrates, and amino acids. ...
-containing enzyme which catalyzes the
carboxylation Carboxylation is a chemical reaction in which a carboxylic acid is produced by treating a substrate with carbon dioxide. The opposite reaction is decarboxylation. In chemistry, the term carbonation is sometimes used synonymously with carboxylation ...
of
acetyl-CoA Acetyl-CoA (acetyl coenzyme A) is a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. Its main function is to deliver the acetyl group to the citric acid cycle (Krebs cycle) to be oxidation, o ...
to
malonyl-CoA Malonyl-CoA is a coenzyme A derivative of malonic acid. Biosynthesis Malonyl-CoA cannot cross membranes and there is no known malonyl-CoA import mechanism. The biosynthesis therefore takes place locally: * cytosol: Malonyl-CoA is formed by c ...
, the rate-limiting step in
fatty acid In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an ...
synthesis. ACC-beta is thought to control fatty acid oxidation by means of the ability of malonyl-CoA to inhibit
carnitine palmitoyltransferase I Carnitine palmitoyltransferase I (CPT1) also known as carnitine acyltransferase I, CPTI, CAT1, CoA:carnitine acyl transferase (CCAT), or palmitoylCoA transferase I, is a mitochondrial enzyme responsible for the formation of acyl carnitines by ca ...
, the rate-limiting step in fatty acid uptake and oxidation by
mitochondria A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is us ...
. ACC-beta may be involved in the regulation of fatty acid oxidation, rather than fatty acid biosynthesis.


Clinical implications

Human acetyl-CoA carboxylase has recently become a target in the design of new anti-obesity drugs. However, when the gene for ACC2 was
knocked out A knockout (abbreviated to KO or K.O.) is a fight-ending, winning criterion in several full-contact combat sports, such as boxing, kickboxing, Muay Thai, mixed martial arts, karate, some forms of taekwondo and other sports involving striking, a ...
in mice, no change in body weight was observed relative to normal mice. This result suggests inhibition of ACC2 by drugs may be an ineffective method of treating obesity.


References


Further reading

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External links

* EC 6.4.1 Human proteins {{gene-12-stub