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

# Fructose-1,6-bisphosphatase (FBPase-1)

Fructose-1,6-bisphosphatase removes a phosphate from fructose 1,6-bisphosphate and is the main control point of gluconeogenesis.

Updated 2026-11-01

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## Key facts

- Fructose 1,6-bisphosphate + H₂O → fructose 6-phosphate + Pi: it bypasses the PFK-1 step.
- It mirrors PFK-1: AMP and fructose-2,6-bisphosphate, which activate PFK-1, inhibit it.
- The 3D structure (1FTA) shows AMP in its allosteric site, away from the active site.

**EC number**
[3.1.3.11](https://www.enzyme-database.org/query.php?ec=3.1.3.11)

**Genes**
FBP1

**Structure (PDB)**
[1FTA](https://www.rcsb.org/structure/1FTA)

## Regulation

- Inhibitors: AMP and fructose-2,6-bisphosphate.
- Glucagon lowers fructose-2,6-bisphosphate and so activates it; insulin does the opposite.

## Inhibitors and toxins

- AMP (allosteric)
- Fructose-2,6-bisphosphate
- Synthetic AMP-site inhibitors (studied for type 2 diabetes)

## Clinical notes

- FBPase-1 deficiency (autosomal recessive) causes hypoglycaemia with lactic acidosis and ketosis during fasting or fever; fructose makes it worse.
- Running together with PFK-1 would create a futile cycle that only burns ATP; reciprocal regulation prevents it.

## Pathways

- [Gluconeogenesis](https://durgical.com/en/biochemistry/pathways/gluconeogenesis/)

## Related conditions

- [Lactic acidosis](https://durgical.com/en/conditions/lactic-acidosis/)
- [Hereditary fructose intolerance](https://durgical.com/en/conditions/hereditary-fructose-intolerance/)

## Related

- [Fructose 1,6-bisphosphate](https://durgical.com/en/biochemistry/molecules/fructose-1-6-bisphosphate/)
- [Phosphofructokinase-1 (PFK-1)](https://durgical.com/en/biochemistry/enzymes/phosphofructokinase-1/)
- [Phosphoenolpyruvate carboxykinase (PEPCK)](https://durgical.com/en/biochemistry/enzymes/phosphoenolpyruvate-carboxykinase/)
- [Glucose-6-phosphatase](https://durgical.com/en/biochemistry/enzymes/glucose-6-phosphatase/)

## Test yourself

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

## Which two molecules inhibit fructose-1,6-bisphosphatase?

AMP and fructose-2,6-bisphosphate; both activate PFK-1.

## What is a futile cycle and how is it avoided at this step?

PFK-1 and FBPase-1 active together would burn ATP for nothing; fructose-2,6-bisphosphate activates one and inhibits the other.

## Why does fructose worsen FBPase-1 deficiency?

Fructose enters as trioses and needs FBPase-1 to become glucose; fructose 1-phosphate also slows glycogenolysis.

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

Sources: [FBP1: Fructose-1,6-bisphosphatase 1 (human)](https://www.uniprot.org/uniprotkb/P09467/entry) (UniProt, 2026); [1FTA: FRUCTOSE-1,6-BISPHOSPHATASE(D-FRUCTOSE-1,6-BISPHOSPHATE, 1-PHOSPHOHYDROLASE) (E.C.3.1.3.11) COMPLEXED WITH THE ALLOSTERIC INHIBITOR AMP](https://www.rcsb.org/structure/1FTA) (RCSB Protein Data Bank, 2026); [Gluconeogenesis](https://reactome.org/PathwayBrowser/#/R-HSA-70263) (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/fructose-1-6-bisphosphatase/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/enzymes/fructose-1-6-bisphosphatase/