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

# ATP synthase (complex V)

ATP synthase is a molecular motor: protons flowing back into the matrix spin it, and each turn makes ATP from ADP and phosphate.

Updated 2026-11-01

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## Key facts

- Two parts: Fo, the proton channel with a c-ring that spins in the membrane, and F1 (α₃β₃γδε), the head in the matrix that makes ATP.
- Binding-change mechanism (Boyer): each β subunit cycles through three states (open, loose, tight); one full turn releases 3 ATP.
- In mammals the c-ring has 8 subunits: about 8 H⁺ per turn, roughly 2.7 H⁺ per ATP plus one to bring in phosphate.
- Oligomycin plugs the Fo channel: ATP synthesis stops and, through respiratory control, so does the chain.

**Also called**
F₀F₁-ATPase, Complex V

**EC number**
[7.1.2.2](https://www.enzyme-database.org/query.php?ec=7.1.2.2)

**Genes**
ATP5F1A, ATP5F1B, MT-ATP6, MT-ATP8…

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

## Regulation

- IF1 restrains it when the gradient collapses (ischemia), so it does not waste ATP running backwards.
- Availability of ADP and phosphate drives it.

## Inhibitors and toxins

- Oligomycin
- Aurovertin
- Dicyclohexylcarbodiimide (DCCD)

## Clinical notes

- MT-ATP6 variants cause NARP or Leigh syndrome depending on the share of mutant copies (heteroplasmy).
- Bacteria use the same machine; bedaquiline, for drug-resistant tuberculosis, blocks the mycobacterial ATP synthase.

## Pathways

- [Electron transport chain and oxidative phosphorylation](https://durgical.com/en/biochemistry/pathways/electron-transport-chain-and-oxidative-phosphorylation/)

## Related conditions

- [Leigh syndrome](https://durgical.com/en/conditions/leigh-syndrome/)

## Related

- [ATP (adenosine triphosphate)](https://durgical.com/en/biochemistry/molecules/atp/)
- [Chemiosmosis and the proton gradient](https://durgical.com/en/biochemistry/topics/chemiosmosis-and-the-proton-gradient/)
- [Uncouplers of oxidative phosphorylation](https://durgical.com/en/biochemistry/topics/uncouplers-of-oxidative-phosphorylation/)
- [UCP1 (thermogenin)](https://durgical.com/en/biochemistry/enzymes/ucp1/)
- [Cytochrome c oxidase (complex IV)](https://durgical.com/en/biochemistry/enzymes/cytochrome-c-oxidase/)

## Test yourself

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

## Which part of ATP synthase spins as protons pass?

The c-ring of the Fo sector, attached to the γ shaft, which turns inside the α₃β₃ head of F1.

## What is the binding-change mechanism?

Each β subunit cycles through open, loose and tight states; the turning γ shaft changes its shape and releases the ATP already made.

## Which inhibitor blocks the Fo channel of ATP synthase?

Oligomycin; it also slows the respiratory chain through respiratory control.

## Which tuberculosis drug acts on the bacterial ATP synthase?

Bedaquiline, used in multidrug-resistant tuberculosis.

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

Sources: [ATP5F1B: ATP synthase F(1) complex subunit beta, mitochondrial (human)](https://www.uniprot.org/uniprotkb/P06576/entry) (UniProt, 2026); [1BMF: BOVINE MITOCHONDRIAL F1-ATPASE](https://www.rcsb.org/structure/1BMF) (RCSB Protein Data Bank, 2026); [MT-ATP6 gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/mt-atp6/) (MedlinePlus, US National Library of Medicine, 2026); [Formation of ATP by chemiosmotic coupling](https://reactome.org/PathwayBrowser/#/R-HSA-163210) (Reactome, 2026).

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Representative model, for educational purposes only.

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