PRNP D178N

01/3D Structure

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This is a predicted 3D structure of the protein. The ribbon diagram shows the protein backbone—helices appear as coils, sheets as arrows, and loops as simple lines. The shape determines how the protein functions: where it binds to other molecules, how it catalyzes reactions, and how mutations might disrupt its activity.

Color legend:

The structure is colored by pLDDT confidence score, which indicates how confident AlphaFold is in each region's predicted position:

Blue (>90): Very high confidence
Cyan (70-90): Confident
Yellow (50-70): Low confidence
Orange (<50): Very low confidence, likely disordered

02/AI Analysis

TLDR

# Analysis of D178N Prion Protein Structure (AlphaFold Prediction) ## TLDR This computational model shows the D178N mutation in prion protein, which causes familial prion disease (specifically familial Creutzfeldt-Jakob disease and fatal familial insomnia). The predicted structure appears reasonably well-defined in most regions, though some flexible loops show lower confidence, which is typical for this protein's naturally disordered N-terminal domain.

Detailed Analysis

## Detailed Structural Analysis ### Structural Confidence (pLDDT Interpretation) The B-factors (reported as pLDDT scores) range from **26–71**, indicating variable confidence across the structure: - **High confidence (pLDDT >60)**: Early N-terminal residues (Met1–Leu11, Val13–Ala14) and scattered mid-region elements show strong predicted reliability, suggesting these form stable secondary structures. - **Moderate confidence (pLDDT 45–60)**: Most of the central and later regions (residues 20–67) display intermediate confidence, typical of helical or loop regions that are intrinsically dynamic. - **Lower confidence (pLDDT <45)**: Several flexible loop regions (particularly around Gly29–Gly30, Gly45–Gly46, Gly53–Gly56) show reduced confidence, consistent with the known flexibility of prion protein's unstructured N-terminal domain. This pattern is **expected and biologically reasonable**—prion protein naturally contains a flexible, unstructured N-terminus that becomes partially ordered upon conversion to the pathogenic PrP^Sc form. --- ### Key Structural Features **Secondary Structure Elements:** - The sequence exhibits multiple turn-promoting residues (Gly, Pro) clustered at positions 5, 20, 28–30, 44–46, 53–56, characteristic of loops or coil regions. - Several hydrophobic residues (Leu, Val, Phe, Trp) form a potential hydrophobic core, important for protein stability. - Two disulfide-forming cysteines are present (Cys6, Cys22), though their bonding state cannot be definitively determined from coordinates alone. These are functionally important in native prion protein. **Notable Residues & Domains:** - **N-terminal Region (Met1–Lys27)**: Relatively unstructured; this is the "flexible domain" that increases accessibility to proteolytic cleavage and may facilitate misfolding. - **Cys6 & Cys22**: These cysteines normally form a disulfide bond critical for structural integrity; disruption of this bond in misfolded PrP^Sc is relevant to disease pathogenesis. - **Tryptophan-rich regions** (Trp7, Trp16, Trp31, Trp57, Trp65): These aromatic residues often participate in hydrophobic packing and may be involved in protein aggregation pathways. --- ### D178N Mutation: Disease Relevance **The D178N substitution** (aspartic acid → asparagine at position 178) is located in the **C-terminal structured region** of prion protein and is one of the most common pathogenic mutations causing: 1. **Familial CJD (fCJD)**: The dominant presentation when paired with the **129-valine polymorphism** (Met129 allele typically associates with fCJD; Val129 with FFI). 2. **Fatal Familial Insomnia (FFI)**: When linked to the methionine-129 polymorphism—characterized by intractable insomnia, autonomic dysfunction, and rapid neurodegeneration. 3. **Familial Gerstmann-Sträussler-Scheinker Syndrome (GSS)**: In some genetic backgrounds. **Structural Consequences of D178N:** - **Loss of negative charge**: Aspartate (Asp, D) is a negatively charged, hydrophilic residue; asparagine (Asn, N) is polar but uncharged. This reduces electrostatic stabilization in the local region. - **Altered hydrogen bonding**: Asparagine can form backbone hydrogen bonds but lacks the extended electrostatic interactions of aspartate, potentially destabilizing local structure or facilitating misfolding. - **Increased aggregation propensity**: The reduced charge likely increases the protein's propensity to self-associate and adopt the pathogenic β-rich PrP^Sc conformation. - **Location significance**: Position 178 is close to the structured C-terminal domain (residues ~120–230), making this mutation particularly disruptive to the native fold. --- ### Biological Relevance to Prion Disease Pathogenesis **Why D178N Causes Disease:** 1. **Destabilized native structure**: The mutation weakens the stability of normal α-helical PrP^C, lowering the energy barrier for conversion to the misfolded PrP^Sc form. 2. **Seeding effect**: Even small amounts of misfolded D178N-PrP can seed conversion of wild-type prion protein, explaining autosomal dominant inheritance and variable penetrance. 3. **Prion propagation**: The altered structure favors formation and propagation of misfolded conformers that resist protease digestion (a hallmark of PrP^Sc). 4. **Phenotypic heterogeneity**: The specific disease manifestation (CJD vs. FFI vs. GSS) depends on: - The genetic background at codon 129 (Met vs. Val) - The specific misfolded PrP^Sc conformer that propagates (strain-like properties) - Environmental and epigenetic factors --- ### Notable Regions in This Structure | Region | Residues | Confidence | Features | |--------|----------|-----------|----------| | **N-terminal flexibility** | Met1–Gly20 | 51–61 (moderate) | Unstructured domain; vulnerable to cleavage; increased in prediction | | **Disulfide region** | Cys6, Cys22 | 61–54 | Functionally critical for native stability | | **Central loops** | Gly29–Gly30, Gly45–Gly56 | 37–43

03/Research Data

Not found in ClinVar

6.84e-07

Extremely rare (<0.01%)

AC: 1 / AN: 1461876

Gerstmann-Straussler-Scheinker syndrome

0.82

literature: 0.18 animal model: 0.42 genetic association: 0.90 genetic literature: 0.89

Creutzfeldt Jacob Disease

0.78

literature: 0.92 animal model: 0.25 genetic association: 0.89 genetic literature: 0.86

Huntington disease-like 1

0.76

literature: 0.04 animal model: 0.26 genetic association: 0.85 genetic literature: 0.85

fatal familial insomnia

0.72

literature: 0.15 genetic association: 0.77 genetic literature: 0.80

inherited Creutzfeldt-Jakob disease

0.72

literature: 0.17 animal model: 0.25 genetic association: 0.83 genetic literature: 0.87

Showing 5 of 996 associations

# Research Brief: PRNP D178N Variant ## Pathogenic Mechanisms The PRNP D178N variant represents a critical mutation in the prion protein gene that drives pathogenesis through altered protein conformation and function. This substitution of aspartic acid to asparagine at position 178 disrupts the normal cellular prion protein (PrP^C) structure, promoting conversion to the pathogenic scrapie form (PrP^Sc). The variant's pathogenic mechanism is uniquely influenced by a polymorphism at codon 129, where the methionine/valine status determines distinct clinical phenotypes. The mutation occurs within a functionally critical region of the protein that normally participates in copper ion binding and cellular stress responses. Given PRNP's known molecular functions including amyloid-beta binding and aspartic-type endopeptidase inhibitor activity, the D178N substitution likely compromises these protective mechanisms while simultaneously enhancing aberrant protein-protein interactions with known interactors such as APP and HTT, potentially accelerating neurotoxic cascades. ## Clinical Significance The D178N variant demonstrates complete penetrance and causes two distinct autosomal dominant prion diseases: Fatal Familial Insomnia (FFI) when coupled with methionine at codon 129, or familial Creutzfeldt-Jakob disease (fCJD) with valine at this position. This genotype-phenotype correlation makes D178N clinically significant as a definitive pathogenic variant requiring careful genetic counseling and codon 129 haplotype determination. FFI typically presents with progressive insomnia, dysautonomia, and motor signs with rapid progression, while the fCJD phenotype manifests with cognitive decline and myoclonus. The critical clinical challenge lies in the pre-symptomatic phase: affected carriers remain asymptomatic for decades before rapid disease onset, making baseline biomarker establishment essential. Current research emphasizes identifying pre-symptomatic changes to define therapeutic intervention windows, as symptom onset signals extremely rapid neurodegeneration with survival typically under 18 months. ## Therapeutic Landscape Therapeutic development for D178N focuses on targeting protein aggregation, with computational analysis identifying a high-probability aggregation hotspot at residues 248-252 (score: 0.83). The candidate peptide CP-PRNP-001 has been designed to specifically target this region, potentially interfering with pathogenic PrP^Sc formation. The therapeutic rationale centers on preventing conformational conversion and subsequent aggregation of the mutant protein. The 248-252 region represents a promising intervention point as it likely participates in the critical nucleation events that drive prion propagation. However, the therapeutic landscape remains largely experimental, with no approved disease-modifying treatments currently available. The challenge lies in developing blood-brain barrier-penetrant agents that can selectively stabilize PrP^C or prevent PrP^Sc accumulation without disrupting normal prion protein function in copper homeostasis and neuroprotective signaling. ## Research Directions Critical knowledge gaps demand urgent investigation: (1) structural characterization of how D178N specifically destabilizes the native fold and promotes misfolding, leveraging AlphaFold predictions alongside experimental validation; (2) identification and validation of pre-symptomatic biomarkers in cerebrospinal fluid and blood that correlate with disease proximity in asymptomatic carriers; (3) natural history studies collecting longitudinal baseline data from mutation carriers to map the earliest detectable pathological changes; (4) validation of CP-PRNP-001 and related aggregation inhibitors in cellular and animal models of D178N-mediated prion disease; and (5) investigation of how codon 129 polymorphism mechanistically determines phenotypic divergence between FFI and fCJD. Additionally, exploring whether modulating PRNP's interactions with APP and HTT could provide therapeutic benefit warrants investigation, given the convergent pathways in neurodegenerative proteinopathies.

Last synthesized: 2026-05-25 14:33 UTC

04/AlphaFold Metrics

No visualization images available.

05/Domain Annotations

Structural Domains & Regions

residues 51–59 Repeat — 1

residues 60–67 Repeat — 2

residues 68–75 Repeat — 3

residues 76–83 Repeat — 4

residues 84–91 Repeat — 5

residues 23–230 Region — Interaction with GRB2, ERI3 and SYN1

residues 23–38 Region — Interaction with ADGRG6

residues 26–108 Region — Disordered

residues 51–91 Region — 5 X 8 AA tandem repeats of P-H-G-G-G-W-G-Q

residues 52–95 Compositional bias — Gly residues

Functional Sites

residue 61 Binding site

residue 62 Binding site

residue 63 Binding site

residue 69 Binding site

residue 70 Binding site

residue 71 Binding site

residue 77 Binding site

residue 78 Binding site

residue 79 Binding site

residue 85 Binding site

residue 86 Binding site

residue 87 Binding site

Binding Partners

HTT (13 experiments)

APP (6 experiments)

PIMREG (5 experiments)

PRNP (5 experiments)

Pkm (5 experiments)

AGO2 (4 experiments)

AZGP1 (4 experiments)

HOXA1 (4 experiments)

MPG (4 experiments)

PLK3 (4 experiments)

Gene Ontology

cell surface GO:0009986 cytoplasm GO:0005737 cytosol GO:0005829 dendrite GO:0030425 endoplasmic reticulum GO:0005783 external side of plasma membrane GO:0009897 extracellular exosome GO:0070062 extrinsic component of membrane GO:0019898 Golgi apparatus GO:0005794 inclusion body GO:0016234 membrane raft GO:0045121 nuclear membrane GO:0031965 plasma membrane GO:0005886 postsynapse GO:0098794 postsynaptic density GO:0014069 +57 more

06/Structural Caption

Structured caption not yet generated. Check back after the next fold analysis.

07/Peptide Therapeutics

Aggregation Analysis

Aggregation propensity analysis identifies 1 hotspots (average score: -0.01) using Pawar+KyteDoolittle+charge algorithm.

Residues 248–252 (0.83)

08/Known Inhibitors

Known Binders from ChEMBL

CHEMBL7568 EC50: 300.0 nM (pChEMBL 6.52)

QUINACRINE

CHEMBL1538068 IC50: 320.71 nM (pChEMBL 6.49)

CHEMBL1538068

CHEMBL1368980 IC50: 412.1 nM (pChEMBL 6.38)

CHEMBL1368980

CHEMBL1587670 IC50: 759.13 nM (pChEMBL 6.12)

CHEMBL1587670

CHEMBL1327902 IC50: 908.0 nM (pChEMBL 6.04)

CHEMBL1327902

CHEMBL1362814 IC50: 1005.0 nM (pChEMBL 6.0)

CHEMBL1362814

CHEMBL1382616 IC50: 1048.0 nM (pChEMBL 5.98)

CHEMBL1382616

CHEMBL1305990 IC50: 1078.0 nM (pChEMBL 5.97)

CHEMBL1305990

CHEMBL1399507 IC50: 1245.0 nM (pChEMBL 5.91)

CHEMBL1399507

CHEMBL1341267 IC50: 1312.0 nM (pChEMBL 5.88)

CHEMBL1341267

09/Candidate Peptides

De Novo Peptide Design Pipeline

Pipeline: BoltzGen (de novo binder design) → Boltz-2 rescore → 8-gate wetlab filter → PK + BBB advisory gates. Target site selected from UniProt curated annotations, P2Rank pocket prediction, and aggregation propensity (in that priority order). Advisory gates annotate each candidate with estimated serum half-life, renal/immunogenicity risk, and (for CNS targets) a recommended blood-brain-barrier shuttle conjugation — without silently dropping designs.

Loading candidate statistics...

Sequences are withheld pending IP review. Full candidate data (sequences, scores, CIF files) is available to authorized reviewers via the /api/private/candidates/{fold_id} endpoint with X-Private-Key.

Legacy candidates (charge-complementary)

Target Region

Residues 248–252 (0.83 aggregation score)

Candidate ID

CP-PRNP-001 (7 residues · computational design)

⚠ Drug-likeness concerns Stability: medium | Toxicity: low

t½ ≈ 4 min renal high ⚙ mods suggested peripheral target

10/Agent Findings

Literature: 1 Clinical: 1 Structural: 1 Synthesis: 1 Supplements: 1 Peptides: 1

Literature Agent (1)

Only one paper directly addresses Fatal Familial Insomnia, which is specifically associated with the PRNP D178N mutation. The other papers discuss different PRNP mutations (V180I/M232R, G114V, T107I) or general prion research in animal models, making them less relevant to the specific D178N variant and its associated phenotypes.

Clinical Agent (1)

The PRNP D178N variant causes fatal familial insomnia (FFI) or familial Creutzfeldt-Jakob disease (fCJD) depending on the methionine/valine polymorphism at codon 129, making this baseline data collection critical for establishing pre-symptomatic biomarkers and disease progression patterns. This initial data will enable clinicians to identify the earliest detectable changes in carriers before symptom onset, potentially allowing for future therapeutic intervention windows and more precise prognostic counseling for affected families. The baseline measurements are essential for developing monitoring protocols since these prion diseases have rapid progression once symptoms appear, making early detection strategies crucial for patient management.

Structural Agent (1)

AlphaFold structure update: Baseline check: 1 structure(s) found

Supplements Agent (1)

The therapeutic landscape for PRNP D178N shows limited development of supplement or peptide-based interventions. Current research focuses primarily on small molecule screens to reduce PrP expression and siRNA gene therapy approaches. No active clinical trials are specifically evaluating dietary supplements, nutritional interventions, or therapeutic peptides for this protein variant.

Synthesis Agent (1)

Synthesis of 1 findings (literature): The PRNP D178N variant continues to be primarily associated with Fatal Familial Insomnia (FFI), a de...

Peptide Agent (1)

PRNP D178N: 10 known binders (top: 300.0 nM); 1 candidate peptides designed