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

# Prion protein (PrP)

The normal prion protein sits on neurons; its misfolded form turns the others into copies of itself and destroys the brain.

Updated 2026-11-01

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## Key facts

- PRNP gene (chromosome 20); normal PrPC is a GPI-anchored membrane glycoprotein, rich in α-helices.
- PrPSc (the disease form) is rich in β-sheets, resists proteases and acts as a template: it converts PrPC into more PrPSc.
- It is the only known transmissible disease caused by a protein alone, with no nucleic acid.
- The codon 129 polymorphism (methionine/valine) changes susceptibility: Met/Met homozygotes are more vulnerable.
- PrPSc resists usual sterilisation (dry heat, formalin, radiation); special protocols are needed.

**Also called**
PrPC and PrPSc, Prion

**Genes**
PRNP

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

## Structure

- Structure 1QLX is normal human PrP (cellular form) solved by NMR: a flexible N-terminal tail and a globular domain with three α-helices and a small β-sheet.
- There is no simple atomic structure of full-length PrPSc; in it much of the helical content turns into β-sheet.

## Regulation

- Strongly expressed in neurons; its normal role is not fully clear (copper binding, myelin maintenance, synaptic signalling).
- PRNP variants (for example E200K, D178N) favour the switch to the disease form.

## Inhibitors and toxins

- No drug that blocks conversion has proven benefit in people
- Decontamination with concentrated sodium hydroxide or hypochlorite and prolonged autoclaving inactivates PrPSc

## Clinical notes

- Creutzfeldt–Jakob disease: sporadic (the commonest), genetic and iatrogenic; variant CJD (vCJD) from eating beef with bovine spongiform encephalopathy.
- Features: dementia progressing over weeks to months, myoclonus and ataxia; tissue shows spongiform change without inflammation.
- The RT-QuIC test on cerebrospinal fluid detects PrPSc's ability to seed new fibres.

## Related conditions

- [Prion diseases (Creutzfeldt–Jakob)](https://durgical.com/en/conditions/prion-diseases/)
- [Alzheimer disease](https://durgical.com/en/conditions/alzheimer-disease/)

## Related

- [Protein structure and folding](https://durgical.com/en/biochemistry/topics/protein-structure-and-folding/)
- [Transthyretin (prealbumin)](https://durgical.com/en/biochemistry/enzymes/transthyretin/)

## Test yourself

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

## How does PrPSc differ from PrPC?

Same sequence, but folded with much β-sheet; it resists proteases and converts PrPC into more PrPSc.

## Which PRNP polymorphism affects prion susceptibility?

Codon 129: methionine/methionine homozygotes are at higher risk, and nearly all vCJD cases are.

## Why can surgical instruments transmit prions?

PrPSc resists the usual dry heat, formalin and radiation; special decontamination protocols are needed.

## Which cerebrospinal fluid test detects prions with high specificity?

RT-QuIC, which amplifies PrPSc's ability to convert normal protein into fibres.

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

Sources: [PRNP: Major prion protein (human)](https://www.uniprot.org/uniprotkb/P04156/entry) (UniProt, 2026); [PRNP gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/prnp/) (MedlinePlus, US National Library of Medicine, 2026); [1QLX: Human prion protein](https://www.rcsb.org/structure/1QLX) (RCSB Protein Data Bank, 2026); [Prion disease: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/prion-disease/) (MedlinePlus, US National Library of Medicine, 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/prion-protein/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/enzymes/prion-protein/