PEX3 Protein - Peroxisome Biogenesis Factor 3

PEX3 Protein — Peroxisome Biogenesis Factor 3

Pathway Diagram

```mermaid
flowchart TD
PEX3["PEX3<br/>Peroxisome Biogenesis<br/>Factor 3"]

SQSTM1["SQSTM1/p62<br/>Autophagy Receptor"]
LC3["LC3<br/>Autophagy Marker"]
RB1CC1["RB1CC1/FIP200<br/>Autophagy Initiation"]

PARKIN["PARKIN<br/>E3 Ubiquitin Ligase"]
SNCA["SNCA<br/>alpha-Synuclein"]
SNCAIP["SNCAIP<br/>Synphilin-1"]

MFN1["MFN1<br/>Mitofusin 1<br/>Mitochondrial Fusion"]
BCL2["BCL2<br/>Anti-apoptotic<br/>Protein"]

ERN1["ERN1/IRE1alpha<br/>ER Stress<br/>Sensor"]
FAM134B["FAM134B<br/>ER-phagy<br/>Receptor"]

ATM["ATM<br/>DNA Damage<br/>Response"]
STING1["STING1<br/>Innate Immunity<br/>Signaling"]

PD["Parkinson's<br/>Disease"]
AD["Alzheimer's<br/>Disease"]
ALS["Amyotrophic<br/>Lateral Sclerosis"]
FTD["Frontotemporal<br/>Dementia"]

PEX3 -->|"regulates"| SQSTM1
SQSTM1 -->|"binds"| LC3
PEX3 -->|"interacts"| RB1CC1

PEX3 -->|"interacts"| PARKIN
PARKIN -->|"ubiquitinates"| SNCA
PEX3 -->|"interacts"| SNCAIP
SNCA -->|"aggregates"| PD

PEX3 -->|"regulates"| MFN1
PEX3 -->|"interacts"| BCL2
MFN1 -->|"maintains"| BCL2

PEX3 -->|"responds_to"| ERN1
PEX3 -->|"interacts"| FAM134B
ERN1 -->|"activates"| FAM134B

PEX3 -->|"interacts"| ATM
PEX3 -->|"modulates"| STING1
ATM -->|"triggers"| STING1

SQSTM1 -->|"dysfunction"| AD
PARKIN -->|"mutations"| PD
ERN1 -->|"stress_response"| ALS
ATM -->|"damage_response"| FTD

style PEX3 fill:#00

PEX3 Protein — Peroxisome Biogenesis Factor 3

Pathway Diagram

Introduction

PEX3 (Peroxisome Biogenesis Factor 3) is an essential integral membrane protein required for peroxisome biogenesis, proliferation, and inheritance. Peroxisomes are critical organelles involved in fatty acid oxidation, plasmalogen synthesis, and [reactive oxygen species](/entities/reactive-oxygen-species) metabolism. Dysfunction of PEX3 and consequent peroxisome deficiency has been increasingly linked to neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, and hereditary spastic paraplegia. This page provides comprehensive coverage of PEX3's structure, function, and role in neuronal health and disease.

<div class="infobox infobox-protein">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">PEX3 Protein</th></tr>
<tr><td><strong>Protein Name</strong></td><td>Peroxisome Biogenesis Factor 3 (Peroxin-3)</td></tr>
<tr><td><strong>Gene</strong></td><td>[PEX3](/genes/pex3)</td></tr>
<tr><td><strong>UniProt ID</strong></td><td><a href="https://www.uniprot.org/uniprot/Q9Y5Y8" target="_blank">Q9Y5Y8</a></td></tr>
<tr><td><strong>PDB ID</strong></td><td>4AWU, 5U7D</td></tr>
<tr><td><strong>Molecular Weight</strong></td><td>52 kDa (424 amino acids)</td></tr>
<tr><td><strong>Subcellular Localization</strong></td><td>Peroxisomal membrane</td></tr>
<tr><td><strong>Protein Family</strong></td><td>PEX3 family</td></tr>
<tr><td><strong>Expression</strong></td><td>Ubiquitous, high in brain, liver, kidney</td></tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/ad" style="color:#ef9a9a">AD</a>, <a href="/wiki/ali" style="color:#ef9a9a">ALI</a>, <a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/alzheimer" style="color:#ef9a9a">Alzheimer</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">242 edges</a></td>
</tr>
</table>
</div>

Overview

PEX3 is an integral peroxisomal membrane protein that serves as the master organizer of peroxisome biogenesis. It is essential for peroxisomal membrane assembly (PMP) formation, protein targeting to peroxisomes, and peroxisome division and inheritance. In [neurons](/entities/neurons), peroxisomes play critical roles in lipid metabolism, antioxidant defense, and inflammatory response regulation—all processes relevant to neurodegeneration.

Structure

PEX3 has a distinctive domain architecture:

Membrane Topology

• N-terminal domain: Cytosolic-facing, involved in protein interactions
• Transmembrane domains: 3-4 predicted TMDs anchoring PEX3 to peroxisomal membrane
• Pex19-binding domain: Site for interaction with PEX19, the PMP targeting factor

Key Interactions

• PEX19: Chaperone and targeting factor for PMPs
• PEX16: Forms heterodimer for membrane insertion
• PEX3-PEX19 complex: Mediates import of all PMPs

Normal Physiological Functions

Peroxisome Biogenesis

PEX3 is central to peroxisome assembly:

Lipid Metabolism

Peroxisomes via PEX3 function:

• β-oxidation: Short and medium-chain fatty acids
• Plasmalogen synthesis: Myelin phospholipids
• Bile acid synthesis: Cholesterol metabolism
• Docosahexaenoic acid (DHA): Important for brain function

Antioxidant Defense

• Catalase: Peroxisomal antioxidant enzyme
• ROS scavenging: Hydrogen peroxide metabolism
• Oxidative stress response: Protects neurons from damage

Neuronal Functions

In the brain, peroxisomes are essential for:

• Myelin maintenance: Plasmalogen synthesis
• Synaptic function: Lipid raft composition
• Neuronal survival: Metabolic and antioxidant support

Role in Neurodegenerative Diseases

Alzheimer's Disease

PEX3 dysfunction contributes to [Alzheimer's disease](/diseases/alzheimers-disease):

Evidence

• Reduced peroxisomes in AD brain
• Altered PEX3 expression in AD
• Impaired peroxisomal function in AD models

Mechanisms

• [Amyloid-beta](/proteins/amyloid-beta): Aβ affects peroxisome function
• Oxidative stress: Peroxisomal antioxidant decline
• Lipid metabolism: Altered plasmalogens in AD brain
• Neuroinflammation: Peroxisome-[microglia](/cell-types/microglia-neuroinflammation) connection

Therapeutic Implications

• Enhancing peroxisome function
• Plasmalogen supplementation
• Antioxidant strategies

Parkinson's Disease

PEX3 is implicated in [Parkinson's disease](/diseases/parkinsons-disease):

• Dopaminergic neurons: Peroxisome function critical
• Mitochondrial function: Peroxisome-mitochondria crosstalk
• Oxidative stress: ROS handling in substantia nigra
• [Alpha-synuclein](/proteins/alpha-synuclein): Peroxisomal dysfunction in Lewy bodies

Hereditary Spastic Paraplegia (HSP)

PEX3 mutations cause peroxisome-related HSP:

• PEX3 deficiency: Severe peroxisome dysfunction
• Spasticity: Upper motor neuron phenotype
• White matter: Myelin abnormalities
• Dementia: In some cases

Zellweger Spectrum

PEX3 mutations cause severe peroxisome biogenesis disorders:

• Zellweger syndrome: Most severe
• Neonatal adrenoleukodystrophy: Intermediate
• Refsum disease: Mildest form

Other Neurodegenerative Conditions

• Huntington's disease: Peroxisomal dysfunction
• Multiple sclerosis: Demyelination connection
• Aging: Declining peroxisome function

Peroxisome-Neuronal Interactions

Peroxisome-Mitochondria Axis

• Metabolic cooperation: Shared fatty acid oxidation
• ROS handling: Combined antioxidant systems
• [Apoptosis](/entities/apoptosis): Cross-talk in cell death pathways

Peroxisome-Microglia Connection

• Inflammatory signaling: Peroxisomes in inflammation
• Phagocytosis: Microglial peroxisomes
• Neuroinflammation: Peroxisomal modulation

Therapeutic Implications

Strategies

• Gene therapy: PEX3 expression restoration
• Small molecules: Peroxisome proliferators
• Plasmalogens: Membrane lipid supplementation
• Antioxidants: Boost peroxisomal antioxidants

Biomarkers

• Blood plasmalogens: Diagnostic potential
• Imaging: Peroxisome-specific PET tracers
• CSF markers: Disease progression markers

Background

The study of Pex3 Protein Peroxisome Biogenesis Factor 3 has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

References

See Also

• [PEX3 Gene](/genes/pex3)
• [Peroxisome](/entities/peroxisome)
• [PEX19 Protein](/proteins/pex19-protein)
• [PEX10 Protein](/proteins/pex10-protein)
• [Zellweger Syndrome](/diseases/zellweger-syndrome)
• [Alzheimer's Disease](/diseases/alzheimers)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Peroxisome Biogenesis](/mechanisms/peroxisome-biogenesis)

External Links

• [<a href="https://www.uniprot.org/uniprot/Q9Y5Y8" target="_blank">UniProt: PEX3</a>](/mechanisms/dopaminergic-neuron-vulnerability)
• [<a href="https://www.ncbi.nlm.nih.gov/gene/8504" target="_blank">NCBI Gene: PEX3</a>](/mechanisms/dopaminergic-neuron-vulnerability)
• [<a href="https://www.hmdb.ca/proteins/Q9Y5Y8" target="_blank">Human Metabolome Database</a>](/proteins)