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

# LCAT (lecithin–cholesterol acyltransferase)

LCAT esterifies free cholesterol on HDL; the ester sinks into the particle core, which matures from a disc into a sphere.

Updated 2026-11-01

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## Key facts

- Moves a fatty acid from lecithin (phosphatidylcholine) to cholesterol: makes cholesteryl ester and lysolecithin.
- The liver makes it and it circulates in plasma; HDL ApoA-I activates it.
- Turns nascent (discoidal) HDL into mature spherical HDL and keeps the gradient that lets HDL keep taking up cholesterol.
- It is a key step of reverse cholesterol transport.

**Also called**
Phosphatidylcholine–sterol acyltransferase

**EC number**
[2.3.1.43](https://www.enzyme-database.org/query.php?ec=2.3.1.43)

**Genes**
LCAT

**Structure (PDB)**
[6MVD](https://www.rcsb.org/structure/6MVD)

## Structure

- An α/β-hydrolase fold with a catalytic serine in a pocket covered by a lid.
- Structure 6MVD holds human LCAT with a fluorophosphonate covalently bound to the active-site serine plus a small activator.

## Regulation

- ApoA-I is its main activator.
- It acts mainly on HDL (alpha activity) and less on LDL (beta activity).

## Inhibitors and toxins

- Fluorophosphonates such as IDFP (experimental)

## Clinical notes

- Familial LCAT deficiency causes corneal clouding, anaemia and progressive kidney damage with very low HDL; the partial form (fish-eye disease) mainly affects the cornea.
- Severe liver disease lowers its activity and disturbs the lipoproteins.
- Without LCAT free cholesterol builds up in red-cell membranes (target cells).

## Related conditions

- [Chronic kidney disease](https://durgical.com/en/conditions/chronic-kidney-disease/)
- [Tangier disease](https://durgical.com/en/conditions/tangier-disease/)
- [Cirrhosis](https://durgical.com/en/conditions/cirrhosis/)

## Related

- [HDL (high-density lipoprotein)](https://durgical.com/en/biochemistry/topics/hdl/)
- [Cholesterol](https://durgical.com/en/biochemistry/molecules/cholesterol/)
- [Lipoprotein metabolism](https://durgical.com/en/biochemistry/topics/lipoprotein-metabolism/)
- [CETP (cholesteryl ester transfer protein)](https://durgical.com/en/biochemistry/enzymes/cetp/)

## Test yourself

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

## What reaction does LCAT catalyse?

It transfers a fatty acid from lecithin to cholesterol: cholesteryl ester and lysolecithin.

## Which apolipoprotein activates LCAT?

HDL's ApoA-I.

## Why does LCAT help HDL keep taking up cholesterol?

Esterifying it hides it in the core: surface free cholesterol falls and the gradient from cells is kept.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/biochemistry/enzymes/lcat/)

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

Sources: [LCAT: Phosphatidylcholine-sterol acyltransferase (human)](https://rest.uniprot.org/uniprotkb/P04180.txt) (UniProt, 2026); [LCAT gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/lcat/) (MedlinePlus, US National Library of Medicine, 2026); [6MVD: Crystal structure of Lecithin:cholesterol acyltransferase (LCAT) in complex with isopropyl dodec-11-enylfluorophosphonate (IDFP) and a small molecule activator](https://www.rcsb.org/structure/6MVD) (RCSB Protein Data Bank, 2026); [Plasma lipoprotein remodeling (R-HSA-8963899)](https://reactome.org/PathwayBrowser/#/R-HSA-8963899) (Reactome, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/biochemistry/enzymes/lcat/
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