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[Biochemistry](https://durgical.com/en/biochemistry/) · Enzyme

# Acetyl-CoA carboxylase (ACC)

Acetyl-CoA carboxylase decides whether the body makes fat: it turns acetyl-CoA into malonyl-CoA using biotin and ATP.

Updated 2026-11-01

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## Key facts

- Rate-limiting step of fatty acid synthesis: acetyl-CoA + HCO₃⁻ + ATP → malonyl-CoA.
- A biotin (B7) enzyme: one domain carboxylates biotin and another hands the carboxyl to acetyl-CoA.
- Citrate activates it by assembling it into filaments; palmitoyl-CoA inhibits it.
- ACC1 is abundant in liver and fat (synthesis); ACC2, in muscle and heart, makes malonyl-CoA that blocks CPT-I.

**Also called**
ACC1 (ACACA, lipogenic), ACC2 (ACACB, mitochondrial)

**EC number**
[6.4.1.2](https://www.enzyme-database.org/query.php?ec=6.4.1.2)

**Genes**
ACACA

**Structure (PDB)**
[8XL1](https://www.rcsb.org/structure/8XL1)

## Regulation

- Insulin activates it (phosphatase) and raises its synthesis; glucagon and adrenaline switch it off by phosphorylation (PKA).
- AMPK, the low-energy sensor, phosphorylates and inactivates it: exercise favours burning fat.

## Inhibitors and toxins

- Avidin (binds biotin)
- Carboxyltransferase-domain inhibitors under study for fatty liver

## Clinical notes

- It is a drug target under study for metabolic dysfunction-associated fatty liver disease.
- Biotinidase or holocarboxylase synthetase deficiency lowers the activity of ACC and the other carboxylases.

## Pathways

- [Fatty acid synthesis (lipogenesis)](https://durgical.com/en/biochemistry/pathways/fatty-acid-synthesis/)

## Related conditions

- [Obesity](https://durgical.com/en/conditions/obesity/)
- [Metabolic syndrome](https://durgical.com/en/conditions/metabolic-syndrome/)

## Related

- [Malonyl-CoA](https://durgical.com/en/biochemistry/molecules/malonyl-coa/)
- [Acetyl-CoA](https://durgical.com/en/biochemistry/molecules/acetyl-coa/)
- [Citrate](https://durgical.com/en/biochemistry/molecules/citrate/)
- [Fatty acid synthase (FAS)](https://durgical.com/en/biochemistry/enzymes/fatty-acid-synthase/)
- [Carnitine palmitoyltransferase I (CPT-I)](https://durgical.com/en/biochemistry/enzymes/carnitine-palmitoyltransferase-i/)
- [ATP (adenosine triphosphate)](https://durgical.com/en/biochemistry/molecules/atp/)

## Test yourself

Think of the answer, then tap the question to see it.

## Which vitamin cofactor does acetyl-CoA carboxylase need?

Biotin (vitamin B7), which carries the carboxyl group.

## What does AMPK do to acetyl-CoA carboxylase?

It phosphorylates and inactivates it: malonyl-CoA falls, CPT-I opens and fatty acids are burned.

## Which metabolite activates acetyl-CoA carboxylase?

Citrate, which signals spare acetyl-CoA and energy in the mitochondrion.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: [ACACA: Acetyl-CoA carboxylase 1 (human)](https://www.uniprot.org/uniprotkb/Q13085/entry) (UniProt, 2026); [Fatty acyl-CoA biosynthesis](https://reactome.org/PathwayBrowser/#/R-HSA-75105) (Reactome, 2026); [8XL1: Core region of the human acetyl-CoA carboxylase 1 filament in complex with acetyl-CoA (ACC1-inact)](https://www.rcsb.org/structure/8XL1) (RCSB Protein Data Bank, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/biochemistry/enzymes/acetyl-coa-carboxylase/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/enzymes/acetyl-coa-carboxylase/