PEX14 (Peroxisome Biogenesis Factor 14)
Overview
PEX14 (Peroxisome Biogenesis Factor 14), also known as peroxin-14, encodes a critical component of the peroxisomal import machinery—the docking receptor for matrix proteins entering the peroxisome lumen. PEX14 serves as the primary interaction point for the peroxisomal targeting signal receptors PEX5 and PEX7, facilitating the translocation of over 100 matrix proteins essential for peroxisome function[@stehlik2005]. Without functional PEX14, peroxisomes cannot import their catalytic enzymes, leading to severe metabolic dysfunction.
Peroxisomes are essential organelles for cellular metabolism, and PEX14 dysfunction has significant implications for neurodegenerative diseases including Alzheimer's disease and Parkinson's disease[@ibayashi2019]. The receptor's central role in importing proteins necessary for fatty acid oxidation, plasmalogen synthesis, and reactive oxygen species metabolism makes it critical for neuronal health.
<div class="infobox infobox-gene">
| Property | Value |
|----------|-------|
| Gene Symbol | PEX14 |
| Full Name | Peroxisome Biogenesis Factor 14 |
| Chromosomal Location | 1p36.22 |
| NCBI Gene ID | 5195 |
| OMIM ID | 603714 |
| Ensembl ID | ENSG00000134001 |
| UniProt ID | Q15818 |
| Encoded Protein | Peroxin-14 |
| Protein Family | PEX proteins, peroxisomal import machinery |
| Protein Length | 377 amino acids |
| Subcellular Location | Peroxisomal membrane |
</div>
Peroxisomal Import Machinery
Overview of Protein Import
...PEX14 (Peroxisome Biogenesis Factor 14)
Overview
PEX14 (Peroxisome Biogenesis Factor 14), also known as peroxin-14, encodes a critical component of the peroxisomal import machinery—the docking receptor for matrix proteins entering the peroxisome lumen. PEX14 serves as the primary interaction point for the peroxisomal targeting signal receptors PEX5 and PEX7, facilitating the translocation of over 100 matrix proteins essential for peroxisome function[@stehlik2005]. Without functional PEX14, peroxisomes cannot import their catalytic enzymes, leading to severe metabolic dysfunction.
Peroxisomes are essential organelles for cellular metabolism, and PEX14 dysfunction has significant implications for neurodegenerative diseases including Alzheimer's disease and Parkinson's disease[@ibayashi2019]. The receptor's central role in importing proteins necessary for fatty acid oxidation, plasmalogen synthesis, and reactive oxygen species metabolism makes it critical for neuronal health.
<div class="infobox infobox-gene">
| Property | Value |
|----------|-------|
| Gene Symbol | PEX14 |
| Full Name | Peroxisome Biogenesis Factor 14 |
| Chromosomal Location | 1p36.22 |
| NCBI Gene ID | 5195 |
| OMIM ID | 603714 |
| Ensembl ID | ENSG00000134001 |
| UniProt ID | Q15818 |
| Encoded Protein | Peroxin-14 |
| Protein Family | PEX proteins, peroxisomal import machinery |
| Protein Length | 377 amino acids |
| Subcellular Location | Peroxisomal membrane |
</div>
Peroxisomal Import Machinery
Overview of Protein Import
Peroxisomes import matrix proteins post-translationally, requiring a sophisticated import machinery[@emory2014]:
Cytosolic receptors: PEX5 (for PTS1), PEX7 (for PTS2)
Docking complex: PEX14 as the primary receptor
Translocation channel: PEX13/PEX14 complex
Recycling machinery: PEX1/PEX6 for receptor exportImport Receptors
PEX5 (PTS1 receptor):
- Recognizes C-terminal SKL motif (PTS1)
- Binds PEX14 after import initiation
- Recycled after cargo delivery
PEX7 (PTS2 receptor):
- Recognizes N-terminal nonapeptide (PTS2)
- Requires PEX5L for function
- Imports specific subset of matrix proteins
Translocation Process
The import process proceeds through[@hu2015]:
Receptor-cargo complex formation in cytosol
Docking at PEX14 on peroxisomal membrane
Translocation through the import channel
Cargo release into peroxisomal matrix
Receptor recycling back to cytosolPEX14 Structure and Function
Protein Architecture
PEX14 is an integral peroxisomal membrane protein:
N-terminal cytosolic domain: Receptor docking site
Membrane-spanning region: Anchors in peroxisomal membrane
C-terminal intraperoxisomal domain: Protein interactionsDocking Function
PEX14 serves as the central docking receptor[@agrawal2011]:
Receptor Binding:
- Binds PEX5-cargo and PEX7-cargo complexes
- Multiple binding sites for different receptors
- Regulated by receptor phosphorylation
Import Initiation:
- Triggers translocation of bound cargo
- Coordinates with PEX2/PEX10/PEX12 translocon
- Ensures proper cargo release
PEX14 interacts with multiple peroxins:
| Protein | Interaction Type | Function |
|---------|-----------------|----------|
| PEX5 | Direct binding | Primary docking receptor |
| PEX7 | Direct binding | PTS2 receptor docking |
| PEX13 | Complex partner | Import channel formation |
| PEX2 | Functional | Ubiquitin ligase complex |
| PEX10 | Functional | Ubiquitin ligase complex |
| PEX12 | Functional | Ubiquitin ligase complex |
Role in Neurodegeneration
Alzheimer's Disease
PEX14 and peroxisomal import are relevant to AD pathogenesis[@kim2019]:
Matrix Protein Import:
- Imported enzymes include catalase, oxidases
- Catalase detoxifies hydrogen peroxide
- Import deficits increase oxidative stress
Lipid Metabolism:
- Peroxisomal β-oxidation handles very long-chain fatty acids
- Defective import reduces metabolic capacity
- Lipid accumulation in neurons
Plasmalogens:
- Import machinery essential for plasmalogen synthesis enzymes
- Plasmalogens critical for synaptic membranes
- Deficits contribute to synaptic dysfunction
Parkinson's Disease
Peroxisomal function connects to PD:
Fatty Acid Metabolism:
- Peroxisomes oxidize long-chain fatty acids
- Altered lipid metabolism in PD
- PEX14 dysfunction compounds deficits
Oxidative Stress:
- Reduced catalase import increases ROS
- Neuronal vulnerability to oxidative damage
- Contributes to dopaminergic neuron loss
Common Mechanisms
Reactive Oxygen Species:
- Catalase deficiency from import failure
- Elevated hydrogen peroxide
- Lipid peroxidation and damage
Energy Metabolism:
- Reduced β-oxidation capacity
- ATP production deficits
- Synaptic dysfunction
Expression Patterns
Tissue Distribution
PEX14 is expressed in most tissues:
| Tissue | Expression Level |
|--------|-----------------|
| Liver | High |
| Kidney | High |
| Brain | High |
| Muscle | Moderate |
| Heart | Moderate |
Brain Regional Distribution
In the brain, PEX14 shows region-specific expression:
| Brain Region | Expression Level | Relevance |
|--------------|-----------------|-----------|
| Cerebral Cortex | High | Cognitive function |
| Hippocampus | High | Memory formation |
| Cerebellum | Moderate | Motor function |
| Substantia Nigra | Moderate | PD relevance |
Cellular Expression
- Neurons: High peroxisome content
- Astrocytes: Peroxisomes for metabolic support
- Oligodendrocytes: Plasmalogen synthesis
- Microglia: ROS metabolism
Clinical Significance
Peroxisome Biogenesis Disorders
PEX14 mutations cause severe PBDs[@goto2011]:
Phenotypes:
- Zellweger syndrome spectrum
- Neonatal adrenoleukodystrophy (NALD)
- Refsum disease (mildest form)
Features:
- Severe neurological impairment
- Developmental delay
- Hepatic dysfunction
- Dysmorphic features
Genetic Considerations
Inheritance: Autosomal recessive
Mechanism: Loss of import function
Diagnosis: Enzymatic testing, genetic analysis
Therapeutic Implications
Targeting Strategies
Gene Therapy:
- Restoration of functional PEX14
- Viral vector delivery approaches
Small Molecules:
- Enhance peroxisome function
- Bypass import deficits
Combination:
- Gene therapy with metabolic support
- Antioxidant therapy
Challenges
BBB penetration: CNS delivery needed
Early intervention: Critical before damage
Mutation-specific: Different variants, different approachesPeroxisomal Matrix Proteins
Imported Enzymes
PEX14-dependent import delivers:
| Enzyme | Function | Relevance |
|--------|----------|-----------|
| Catalase | H2O2 detoxification | Antioxidant |
| Acyl-CoA oxidase | β-oxidation | Lipid metabolism |
| Bifunctional enzyme | β-oxidation | Lipid metabolism |
| D-amino acid oxidase | Amino acid metabolism | Neurotransmission |
| Urate oxidase | Purine metabolism | Oxidative stress |
Health Implications
Loss of any imported enzyme causes specific metabolic diseases and contributes to neurodegeneration.
Research Directions
Unanswered Questions
How is PEX14 expression regulated in neurons?
Can targeting PEX14 benefit neurodegenerative disease?
What determines regional vulnerability in the brain?Emerging Research
- Peroxisome-targeted therapeutics
- Gene therapy development
- Biomarker identification
See Also
- [Peroxisomal Import Machinery](/mechanisms/peroxisomal-import-machinery)
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
- [PEX Gene Family](/genes/pex-gene-family)
- [Peroxisome Biogenesis](/mechanisms/peroxisome-biogenesis)
- [Oxidative Stress](/mechanisms/oxidative-stress-neurodegeneration)
External Links
- [Ensembl: ENSG00000134001](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000134001)
- [NCBI Gene: PEX14](https://www.ncbi.nlm.nih.gov/gene/5195)
- [GeneCards: PEX14](https://www.genecards.org/cgi-bin/carddisp.pl?gene=PEX14)
- [OMIM: 603714](https://www.omim.org/entry/603714)
- [UniProt: Q15818](https://www.uniprot.org/uniprotkb/Q15818/)
References
[Stehlik et al., The peroxin PEX14 (2005)](https://pubmed.ncbi.nlm.nih.gov/16126221/)
[Agrawal et al., PEX14 is a matrix protein import receptor (2011)](https://pubmed.ncbi.nlm.nih.gov/21555562/)
[Itsumi et al., PEX14 and peroxisomal matrix protein import (2012)](https://pubmed.ncbi.nlm.nih.gov/22431279/)
[Emory et al., Peroxisomal matrix protein import (2014)](https://pubmed.ncbi.nlm.nih.gov/24739576/)
[Hu et al., Import of peroxisomal matrix proteins (2015)](https://pubmed.ncbi.nlm.nih.gov/25447656/)
[Wiese et al., PEX14: docking platform for matrix protein import (2007)](https://pubmed.ncbi.nlm.nih.gov/17606993/)
[Sakakura et al., PEX14 deficiency leads to peroxisome deficiency (2017)](https://pubmed.ncbi.nlm.nih.gov/29084718/)
[Goto et al., PEX14 and human disease (2011)](https://pubmed.ncbi.nlm.nih.gov/21247952/)
[Iba et al., Peroxisomes in neurodegenerative disease (2019)](https://pubmed.ncbi.nlm.nih.gov/30778852/)
[Terlecky et al., Peroxisomes and oxidative stress (2012)](https://pubmed.ncbi.nlm.nih.gov/22305953/)Pathway Diagram
The following diagram shows the key molecular relationships involving pex14 discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)
Pathway Diagram
The following diagram shows the key molecular relationships involving PEX14 (Peroxisome Biogenesis Factor 14) discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)