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

# α-Galactosidase A

α-Galactosidase A removes the terminal galactose from globotriaosylceramide in the lysosome. Its X-linked loss causes Fabry disease.

Updated 2026-11-01

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## Key facts

- Globotriaosylceramide (Gb3) + H₂O → lactosylceramide + galactose.
- A lysosomal homodimer; the GLA gene is on the X chromosome (Xq22).
- It needs saposin B to reach the lipid.
- Its deficiency stores Gb3 and lyso-Gb3 in endothelium, podocytes, cardiomyocytes and sensory neurons.

**Also called**
Ceramide trihexosidase, α-Gal A

**EC number**
[3.2.1.22](https://www.enzyme-database.org/query.php?ec=3.2.1.22)

**Genes**
GLA

**Structure (PDB)**
[3S5Y](https://www.rcsb.org/structure/3S5Y)

## Regulation

- Active at acid pH.
- Reaches the lysosome through the mannose 6-phosphate route.

## Inhibitors and toxins

- Migalastat (1-deoxygalactonojirimycin, DGJ), the ligand in the 3D model: a chaperone that stabilises foldable variants

## Clinical notes

- Fabry disease: neuropathic pain in hands and feet, angiokeratomas, hypohidrosis, cornea verticillata, proteinuria and cardiomyopathy.
- In males, plasma or leukocyte activity is diagnostic; in females it can be normal and genetic testing is needed.
- Treatment: enzyme replacement or, if the variant responds, an oral chaperone.

## Related conditions

- [Fabry disease](https://durgical.com/en/conditions/fabry-disease/)
- [Chronic kidney disease](https://durgical.com/en/conditions/chronic-kidney-disease/)

## Related

- [Sphingolipids and sphingolipidoses](https://durgical.com/en/biochemistry/topics/sphingolipids-and-sphingolipidoses/)
- [Lysosomal storage diseases](https://durgical.com/en/biochemistry/topics/lysosomal-storage-diseases/)
- [Galactose](https://durgical.com/en/biochemistry/molecules/galactose/)
- [Ceramide](https://durgical.com/en/biochemistry/molecules/ceramide/)

## Test yourself

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

## Which substrate builds up in α-galactosidase A deficiency?

Globotriaosylceramide (Gb3) and its deacylated form, lyso-Gb3.

## Why can enzyme activity be normal in women with Fabry disease?

Random X inactivation: many cells express the healthy allele.

## How does migalastat work?

It binds the active site of certain misfolded variants, stabilises them and lets them reach the lysosome.

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

Sources: [GLA: Alpha-galactosidase A (human)](https://www.uniprot.org/uniprotkb/P06280/entry) (UniProt, 2026); [GLA gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/gla/) (MedlinePlus, US National Library of Medicine, 2026); [3S5Y: Pharmacological Chaperoning in Human alpha-Galactosidase](https://www.rcsb.org/structure/3S5Y) (RCSB Protein Data Bank, 2026); [Glycosphingolipid metabolism](https://reactome.org/PathwayBrowser/#/R-HSA-1660662) (Reactome, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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Representative model, for educational purposes only.

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