PRNP — Prion Protein

PRNP — Prion Protein

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">PRNP — Prion Protein</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>PRNP</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Prion Protein (Kanno Blood Group)</td>
</tr>
<tr>
<td class="label">Chromosome</td>
<td>20p13</td>
</tr>
<tr>
<td class="label">NCBI Gene</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/5621" target="_blank">5621</a></td>
</tr>
<tr>
<td class="label">Ensembl</td>
<td><a href="https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000171867" target="_blank">ENSG00000171867</a></td>
</tr>
<tr>
<td class="label">OMIM</td>
<td><a href="https://omim.org/entry/176640" target="_blank">176640</a></td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/P04156" target="_blank">P04156</a></td>
</tr>
<tr>
<td class="label">Diseases</td>
<td>[Creutzfeldt-Jakob Disease](/diseases/creutzfeldt-jakob-disease), [Fatal Familial Insomnia](/diseases/fatal-familial-insomnia), [Gerstmann-Straussler-Scheinker](/diseases/gerstmann-straussler-scheinker)</td>
</tr>
<tr>
<td class="label">Expression</td>
<td>Cerebral cortex, Cerebellum, Hippocampus, Thalamus, Basal ganglia, Brainstem</td>
</tr>
<tr>
<th class="infobox-subheader" colspan="2">Key Mutations</th>
</tr>
<tr>
<td colspan="2" style="font-size:0.85em">E200K (most common gCJD)<br>D178N (FFI/gCJD modifier)<br>P102L (GSS)<br>A117V

PRNP — Prion Protein

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">PRNP — Prion Protein</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>PRNP</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Prion Protein (Kanno Blood Group)</td>
</tr>
<tr>
<td class="label">Chromosome</td>
<td>20p13</td>
</tr>
<tr>
<td class="label">NCBI Gene</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/5621" target="_blank">5621</a></td>
</tr>
<tr>
<td class="label">Ensembl</td>
<td><a href="https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000171867" target="_blank">ENSG00000171867</a></td>
</tr>
<tr>
<td class="label">OMIM</td>
<td><a href="https://omim.org/entry/176640" target="_blank">176640</a></td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/P04156" target="_blank">P04156</a></td>
</tr>
<tr>
<td class="label">Diseases</td>
<td>[Creutzfeldt-Jakob Disease](/diseases/creutzfeldt-jakob-disease), [Fatal Familial Insomnia](/diseases/fatal-familial-insomnia), [Gerstmann-Straussler-Scheinker](/diseases/gerstmann-straussler-scheinker)</td>
</tr>
<tr>
<td class="label">Expression</td>
<td>Cerebral cortex, Cerebellum, Hippocampus, Thalamus, Basal ganglia, Brainstem</td>
</tr>
<tr>
<th class="infobox-subheader" colspan="2">Key Mutations</th>
</tr>
<tr>
<td colspan="2" style="font-size:0.85em">E200K (most common gCJD)<br>D178N (FFI/gCJD modifier)<br>P102L (GSS)<br>A117V (GSS variant)<br>V210I (low-penetrance gCJD)</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/alzheimer" style="color:#ef9a9a">Alzheimer</a>, <a href="/wiki/ms" style="color:#ef9a9a">Ms</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">6 edges</a></td>
</tr>
</table>

PRNP — Prion Protein

Overview

PRNP (Prion Protein, also known as CD230 or Kanno blood group antigen) is a gene located on chromosome 20p13 that encodes the major prion protein (PrP), a glycosylphosphatidylinositol (GPI)-anchored glycoprotein of 253 amino acids["@genetic2003"]. The PRNP gene spans approximately 16 kb and contains two exons, with the entire open reading frame encoded within exon 2[@genetic2022]. PrP is expressed prominently in the central nervous system — particularly in [neurons](/cell-types/neurons) — but is also found in many other tissues throughout the body.

PRNP is the causative gene for all inherited forms of human [prion diseases](/diseases/prion-diseases), which are a unique class of fatal neurodegenerative disorders that can be sporadic, inherited, or acquired through infection["@genetic2022"][@characterization2018]. Pathogenic mutations in PRNP account for approximately 10-15% of all Creutzfeldt-Jakob disease (CJD) cases, following an autosomal dominant pattern with variable penetrance["@characterization2018"]. The remaining ~85% of cases are sporadic (sCJD), and ~1% are acquired through transmission of misfolded PrP.

Beyond prion diseases, cellular prion protein (PrP-C) has emerged as a significant player in [Alzheimer's disease](/diseases/alzheimers-disease) as a receptor for [amyloid-beta](/proteins/amyloid-beta) oligomers, mediating A-beta toxicity and uptake["@prp_aby_receptor2024"][@mirna_ad2024].

Normal Cellular Function

PrP-C Structure

The normal cellular form of the prion protein, designated PrP-C, adopts a predominantly alpha-helical structure[@phenotypic2021]:

• N-terminal domain (residues 1-120): Flexible, intrinsically disordered region containing an octapeptide repeat sequence (PHGGGWGQ repeated 4 times at residues 51-91) that binds copper ions and other metal ions
• C-terminal domain (residues 121-253): Structured region containing three alpha-helices (H1, H2, H3) and a short antiparallel beta-sheet, stabilized by a single disulfide bond between C179 and C214
• GPI anchor: Attached to C253, tethering PrP-C to the outer leaflet of the cell membrane

Physiological Roles

Although the precise physiological role of PrP-C remains incompletely understood, it has been implicated in multiple cellular processes[@major2007]:

• Copper binding and metal ion homeostasis: The octapeptide repeat region binds copper ions with micromolar affinity and may regulate oxidative stress responses
• Cell signaling and neuroprotection: PrP-C participates in signal transduction pathways that promote neuronal survival; it activates neuroprotective pathways including the Phosphoinositide 3-kinase (PI3K)/Akt pathway
• Synaptic function: PrP-C is enriched at synapses where it interacts with [NMDA receptors](/proteins/nmda-receptor), contributing to synaptic plasticity and [long-term potentiation](/mechanisms/long-term-potentiation)[@phenotypic2021]
• Myelin maintenance: PrP-C expressed by [neurons](/cell-types/neurons) signals to [oligodendrocytes](/cell-types/oligodendrocytes) to maintain myelin integrity[@genetic2003]
• Stem cell renewal: PrP-C plays roles in hematopoietic and neural stem cell self-renewal[@phenotypic2021]
• Cell adhesion: PrP-C interacts with extracellular matrix proteins and mediates cell-cell adhesion through homophilic interactions

PrP-C as an Amyloid-Beta Receptor

A major development in AD research is the identification of PrP-C as a receptor for amyloid-beta oligomers[@prp_aby_receptor2024]. PrP-C binds A-beta oligomers through its N-terminal domain, triggering intracellular signaling cascades that lead to:

Notably, recent work found that PrP-C does not affect [tau](/proteins/tau-protein) seeding in AD, suggesting its role is specific to A-beta-mediated toxicity rather than affecting the tau pathology axis[@tau_seeding_prp2024].

Disease-Associated Prion Protein (PrP-Sc)

In prion diseases, PrP-C undergoes a conformational change to an abnormal isoform designated PrP-Sc (Sc for scrapie), which is characterized by[@genetic2022][@characterization2018]:

• Beta-sheet enrichment: The alpha-helical content is converted to a high beta-sheet content
• Protease resistance: PrP-Sc is partially resistant to proteinase K digestion (a defining biochemical feature)
• Insolubility: PrP-Sc is insoluble in non-ionic detergents
• Amyloid formation: PrP-Sc polymerizes into amyloid fibrils that form the characteristic prion plaques
• Self-propagation: PrP-Sc acts as a template to convert additional PrP-C molecules into the misfolded form — the "seeded polymerization" or "protein-only" model of prion propagation[@genetic2022]

Disease Associations

Genetic Creutzfeldt-Jakob Disease (gCJD)

The most common form of inherited Prion Disease, gCJD typically presents with rapidly progressive dementia, myoclonus, and cerebellar ataxia[@characterization2018]. The E200K mutation (glutamate to lysine at position 200) is the most prevalent cause of gCJD worldwide, with notable clusters in Libyan Jews, Slovakian populations, and Chilean families. The V210I mutation causes gCJD with low penetrance (approximately 10%)[@genetic2022].

Fatal Familial Insomnia (FFI)

FFI is caused by the D178N mutation (aspartate to asparagine at position 178) when methionine is present at codon 129 in cis (D178N-129M)[@neuropathologically2024]. This demonstrates a remarkable example of how a single polymorphism can determine entirely different disease phenotypes from the same point mutation. FFI is characterized by progressive insomnia, dysautonomia, hallucinations, and selective thalamic degeneration — particularly of the medio-dorsal and anterior thalamic nuclei[@genetic2022][@neuropathologically2024].

Gerstmann-Straussler-Scheinker Syndrome (GSS)

GSS is primarily associated with the P102L mutation and presents with slowly progressive cerebellar ataxia, followed by dementia, typically over several years. The A117V mutation causes another variant of GSS[@genetic2022][@characterization2018]. GSS is characterized neuropathologically by multicentric amyloid plaques composed of PrP fragments, without the classic spongiform change seen in CJD[@characterization2018].

Variable Phenotype Based on Codon 129

The methionine/valine polymorphism at codon 129 (M129V) is the most important genetic modifier of prion disease susceptibility and phenotype[@genetic2022][@neuropathologically2024]. This polymorphism creates a comprehensive genotype-phenotype map:

| PRNP Mutation | 129M/M | 129M/V | 129V/V |
|---------------|--------|--------|--------|
| D178N | FFI | gCJD | gCJD |
| E200K | gCJD | gCJD | gCJD (reduced penetrance) |
| P102L | GSS | GSS/CJD | GSS |
| V210I | gCJD | gCJD (lower penetrance) | gCJD (rare) |

Homozygosity at codon 129 (either M/M or V/V) increases susceptibility to sporadic CJD. All clinical cases of variant CJD (vCJD) to date have been homozygous for methionine (M/M) at codon 129[@neuropathologically2024].

Prion Disease Phenotype Classification

A 2021 Acta Neuropathologica study established a histo-molecular classification of genetic CJD based on the type of prion protein aggregation detected by real-time quaking-induced conversion (RT-QuIC) and neuropathological features[@phenotypic2021]. This classification identifies distinct prion strains within genetic disease:

• MM1/MV1 sCJD-like: Most common, rapid progression, classic histopathology
• MM2 (cortical): Slow progression, kuru-type plaques
• MM2 (thalamic): FFI-like phenotype, severe thalamic involvement
• VV2: Cerebellar onset, prominent ataxia, spongiform change
• Mixed types: Various combinations reflecting distinct prion strains

PrP in Alzheimer's Disease

Recent research has identified PrP-C as a key receptor mediating A-beta toxicity[@prp_aby_receptor2024]. The interaction between PrP-C and A-beta oligomers activates downstream signaling cascades that:

A 2024 study identified miR-519a-3p as a regulator of PrP-C expression during AD pathogenesis, suggesting its potential as a biomarker for asymptomatic AD stages[@mirna_ad2024].

Key Mutations

| Mutation | Codon 129 Effect | Phenotype | Key Features |
|----------|-----------------|-----------|-------------|
| E200K | M129 in cis | gCJD (most common) | Incomplete, age-associated penetrance; clusters in specific populations |
| D178N-129M | Met at 129 | FFI | Sleep disruption, dysautonomia, thalamic degeneration |
| D178N-129V | Val at 129 | gCJD | Rapidly progressive dementia |
| P102L | M129 in cis | GSS | Slow progressive ataxia, dementia |
| A117V | M129 in cis | GSS variant | Psychiatric features, prominent dementia |
| V210I | M129 in cis | gCJD (low penetrance) | ~10% penetrance, variable age of onset |
| V180I | M129 in cis | gCJD (very low penetrance) | ~1% penetrance, atypical presentation |
| M232R | M129 in cis | gCJD | iPSC model generated 2024[@mirna_ad2024] |
| Octapeptide repeat insertions | Variable | CJD/GSS | Extra copies of the PHGGGWGQ repeat; variable penetrance |
| Octapeptide repeat deletions | Variable | CJD | Loss of repeat units; rare |

Brain Expression

PRNP is widely expressed throughout the brain[@major2007], with highest levels in:

• [Cortex](/brain-regions/cortex) (particularly neocortical neurons in layers III and V)
• [Hippocampus](/brain-regions/hippocampus) (CA1 pyramidal neurons and dentate gyrus granule cells)
• [Cerebellum](/brain-regions/cerebellum) (Purkinje cells)
• [Thalamus](/brain-regions/thalamus) (medial dorsal nucleus)
• [Basal ganglia](/brain-regions/basal-ganglia) (striatum, especially in FFI)
• [Brainstem](/brain-regions/brainstem) (especially in brainstem nuclei)

Emerging Research

New Prion Strains

A 2025 study isolated a novel human prion strain from a PRNP codon 129 heterozygous vCJD patient, expanding the understanding of prion strain diversity[@isolation2025]. This finding has implications for the accuracy of diagnostic tests and the understanding of vCJD pathogenesis.

Genetic Modifiers

A 2025 Lancet Neurology review comprehensively catalogued genetic causes and modifiers of prion diseases, identifying over 60 pathogenic PRNP variants and numerous modifiers beyond codon 129[@genetic2025]. These include polymorphisms in PRNP flanking genes and copy number variations.

Therapeutic Approaches

Research into prion disease therapeutics has identified several promising approaches:

• Antisense oligonucleotides (ASOs): Targeting PRNP mRNA to reduce PrP expression; preclinical studies in mice show delayed disease onset and extended survival
• Small molecule stabilizers: Compounds that stabilize the normal PrP-C conformation and prevent conversion to PrP-Sc
• Prion replication inhibitors: Compounds that disrupt the conversion process, including compounds targeting the N-terminal domain
• S100A9 interaction: S100A9 (a calcium-binding protein) has been shown to inhibit and redirect prion protein amyloid aggregation, suggesting a potential therapeutic strategy[@s100a9_prp2024]

Animal Models

• PRNP knockout mice: Viable and fertile; show subtle phenotypes including altered copper metabolism, impaired long-term potentiation, and resistance to prion infection
• Z2H-PrP transgenic mice: Overexpress human PrP with M129; susceptible to human prion strains
• Ki-HaPrP mice: Knock-in mice expressing human PRNP with 129M polymorphism; model human susceptibility
• PrP-null Göttingen minipigs: Large animal model for prion disease research

See Also

• [Creutzfeldt-Jakob Disease](/diseases/creutzfeldt-jakob-disease) — The most common prion disease
• [Fatal Familial Insomnia](/diseases/fatal-familial-insomnia) — Thalamic prion disease
• [Gerstmann-Straussler-Scheinker](/diseases/gerstmann-straussler-scheinker) — Prion disease with amyloid plaques
• [Alzheimer's Disease](/diseases/alzheimers-disease) — PrP as A-beta receptor
• [Prion Diseases](/diseases/prion-diseases) — Overview of all prion diseases
• [Amyloid-Beta Toxicity](/mechanisms/amyloid-beta-toxicity) — PrP-C mediates A-beta signaling
• [Amyloid Cascade Hypothesis](/mechanisms/amyloid-cascade-hypothesis) — Central AD hypothesis

External Links

• [NCBI Gene: PRNP](https://www.ncbi.nlm.nih.gov/gene/5621)
• [Ensembl: ENSG00000171867](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000171867)
• [OMIM: 176640](https://omim.org/entry/176640)
• [UniProt: P04156](https://www.uniprot.org/uniprot/P04156)
• [Allen Human Brain Atlas: PRNP](https://human.brain-map.org/microarray/search/show?search_term=PRNP)
• [Alzforum Mutations Database: PRNP](https://www.alzforum.org/mutations/prnp)

Pathway Diagram

The following diagram shows the key molecular relationships involving PRNP — Prion Protein discovered through SciDEX knowledge graph analysis: