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

# Na⁺/K⁺-ATPase (sodium pump)

The sodium pump spends ATP to push Na⁺ out of the cell and bring K⁺ in. Digoxin blocks it in the heart.

Updated 2026-11-01

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## Key facts

- Each ATP moves 3 Na⁺ out and 2 K⁺ in, against both gradients.
- A P-type ATPase: during each cycle it is briefly phosphorylated (states such as E2P) while it changes shape.
- The gradients it builds keep the membrane potential and the ion balance of the cell.
- It sits in the plasma membrane, on the basolateral side in epithelia.

**Also called**
Sodium–potassium pump

**EC number**
[7.2.2.13](https://www.enzyme-database.org/query.php?ec=7.2.2.13)

**Genes**
ATP1A1

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

## Structure

- Catalytic α subunit (ATP1A1 is the isoform found in most cells), plus a β subunit and an FXYD regulator.
- Structure 4RET is the pig kidney pump in the E2P state with digoxin bound on its outer face.

## Regulation

- The α/β/FXYD combination in each tissue tunes how the pump behaves.
- Phosphorylation by kinases (PKA among them) and dephosphorylation adjust its activity.

## Inhibitors and toxins

- Cardiac glycosides (digoxin): bind the outer face and block the pump.
- Ouabain and digitoxin, other cardiac glycosides.

## Clinical notes

- In heart muscle, less pumping leaves more Na⁺ inside; the Na⁺/Ca²⁺ exchanger then removes less Ca²⁺, so contraction gets stronger.
- Digoxin also boosts vagal tone, slowing the AV node: used in heart failure and to control rate in atrial fibrillation.
- Low potassium, low magnesium, high calcium and poor kidney function raise the risk of digoxin toxicity.
- ATP1A1 variants cause a hereditary axonal neuropathy and a syndrome with low magnesium and seizures.

## Drugs that act here

- [Digoxin](https://durgical.com/en/pharmacology/digoxin/)

## Related conditions

- [Heart failure](https://durgical.com/en/conditions/heart-failure/)
- [Atrial fibrillation](https://durgical.com/en/conditions/atrial-fibrillation/)
- [Chronic kidney disease](https://durgical.com/en/conditions/chronic-kidney-disease/)

## Related

- [H⁺/K⁺-ATPase (gastric proton pump)](https://durgical.com/en/biochemistry/enzymes/h-k-atpase/)
- [ATP (adenosine triphosphate)](https://durgical.com/en/biochemistry/molecules/atp/)

## Test yourself

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

## How many Na⁺ and K⁺ does the pump move per ATP?

3 Na⁺ out and 2 K⁺ in.

## How does blocking the pump make the heart beat harder?

More Na⁺ stays inside, the Na⁺/Ca²⁺ exchanger expels less Ca²⁺, and more Ca²⁺ is available for contraction.

## Which findings raise the risk of digoxin toxicity?

Low potassium, low magnesium, high calcium and reduced kidney function.

## Which subunits make up the sodium pump?

A catalytic α subunit, a β subunit and an FXYD regulatory subunit.

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

Sources: [ATP1A1: Sodium/potassium-transporting ATPase subunit alpha-1 (human)](https://rest.uniprot.org/uniprotkb/P05023.txt) (UniProt, 2026); [4RET: Crystal structure of the Na,K-ATPase E2P-digoxin complex with bound magnesium](https://www.rcsb.org/structure/4RET) (RCSB Protein Data Bank, 2026); [DIGOXIN tablet](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=dfac7f13-28be-423d-9389-9089da29da17) (DailyMed, US National Library of Medicine, 2026); [Digoxin: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a682301.html) (MedlinePlus, US National Library of Medicine, 2026).

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Representative model, for educational purposes only.

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