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

# Phosphofructokinase-1 (PFK-1)

Phosphofructokinase-1 is the main switch of glycolysis: it decides whether glucose is burned according to the cell's energy.

Updated 2026-10-31

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## Key facts

- Fructose 6-phosphate + ATP → fructose 1,6-bisphosphate + ADP: the committed, rate-limiting step.
- A tetrameric allosteric enzyme: ATP is both substrate and inhibitor (it binds a second site).
- Muscle uses the PFKM isoform; liver PFKL; red cells mix both.

**EC number**
[2.7.1.11](https://www.enzyme-database.org/query.php?ec=2.7.1.11)

**Genes**
PFKM, PFKL, PFKP

**Structure (PDB)**
[4PFK](https://www.rcsb.org/structure/4PFK)

## Regulation

- Activators: AMP, ADP and fructose 2,6-bisphosphate (made by PFK-2, which insulin switches on).
- Inhibitors: ATP, citrate and H⁺; glucagon lowers fructose 2,6-bisphosphate in the liver.

## Inhibitors and toxins

- Citrate (signal that the Krebs cycle is full)
- Acidity: slows glycolysis in very tired muscle

## Clinical notes

- PFKM deficiency (Tarui disease, glycogen storage disease VII) causes exercise cramps, myoglobinuria and compensated hemolysis.
- In Tarui disease, a carbohydrate-rich meal before exercise makes symptoms worse: it lowers the fatty acids muscle could use.

## Pathways

- [Glycolysis](https://durgical.com/en/biochemistry/pathways/glycolysis/)

## Related conditions

- [Tarui disease (muscle phosphofructokinase deficiency)](https://durgical.com/en/conditions/tarui-disease/)

## Related

- [Fructose 1,6-bisphosphate](https://durgical.com/en/biochemistry/molecules/fructose-1-6-bisphosphate/)
- [ATP (adenosine triphosphate)](https://durgical.com/en/biochemistry/molecules/atp/)

## Test yourself

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

## What is the strongest activator of PFK-1?

Fructose 2,6-bisphosphate, which rises with insulin in the liver.

## Why does citrate inhibit PFK-1?

It signals that the Krebs cycle has fuel to spare; it slows the entry of glucose.

## What disease does muscle PFK deficiency cause?

Glycogen storage disease type VII (Tarui): exercise intolerance, cramps, myoglobinuria and hemolysis.

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

Sources: [PFKM: ATP-dependent 6-phosphofructokinase, muscle type (human)](https://www.uniprot.org/uniprotkb/P08237/entry) (UniProt, 2026); [Glycogen storage disease type VII: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/glycogen-storage-disease-type-vii/) (MedlinePlus, US National Library of Medicine, 2026); [4PFK: Phosphofructokinase: structure and control](https://www.rcsb.org/structure/4PFK) (RCSB Protein Data Bank, 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/phosphofructokinase-1/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/enzymes/phosphofructokinase-1/