Biochemistry · Enzyme
Glycogen debranching enzyme !
The debranching enzyme removes glycogen's branches so phosphorylase can keep going; it has two activities in a single protein.
Updated 2026-11-01
Loading the 3D model…
Key facts
- Transferase activity (4-α-glucanotransferase): it moves a block of 3 glucose units from the branch to another chain.
- Glucosidase activity (amylo-α-1,6-glucosidase): it hydrolyses the last α-1,6-linked glucose and frees it as free glucose.
- A single polypeptide chain encoded by the AGL gene.
- Structure 8ZEQ (cryo-EM, human) has no bound ligand: the whole protein is shown.
- EC number
- 2.4.1.25, 3.2.1.33
- Genes
- AGL
- Structure (PDB)
- 8ZEQ
Regulation
- No direct hormonal regulation is known: it works at the pace set by phosphorylase.
Inhibitors and toxins
- No clinically used inhibitors
Clinical notes
- Its deficiency is Cori disease (GSD III): limit dextrin with short branches accumulates; hepatomegaly, hypoglycaemia and, in type IIIa, myopathy and cardiomyopathy.
- Unlike GSD I, in GSD III lactate and uric acid are usually normal because gluconeogenesis works.
Pathways
Related conditions
Related
Test yourself
Think of the answer, then tap the question to see it.
What are the two activities of the debranching enzyme?
Transferase (moves 3 glucose units to another chain) and α-1,6-glucosidase (frees the glucose at the branch point).
What accumulates in Cori disease?
Glycogen with short outer branches (limit dextrin), because phosphorylase cannot get past the branches.
Why is lactate normal in GSD III but not in GSD I?
In GSD III glucose-6-phosphatase works and gluconeogenesis continues; in GSD I that final step is blocked.
Educational information, not medical advice. For any symptom, see a health professional.
Sources: AGL: Glycogen debranching enzyme (human) (UniProt, 2026); AGL gene: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2026); 8ZEQ: Molecular Architecture of Human Glycogen Debranching Enzyme: Insights into Glycogen Storage Disease III Pathogenesis (RCSB Protein Data Bank, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.