PEX14 (Peroxisome Biogenesis Factor 14)

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]:

Import Receptors

PEX5 (PTS1 receptor):

• Recognizes C-terminal SKL motif (PTS1)
• Binds PEX14 after import initiation
• Recycled after cargo delivery

• Recognizes N-terminal nonapeptide (PTS2)
• Requires PEX5L for function
• Imports specific subset of matrix proteins

Translocation Process

The import process proceeds through[@hu2015]:

PEX14 Structure and Function

Protein Architecture

PEX14 is an integral peroxisomal membrane protein:

Docking 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

• Triggers translocation of bound cargo
• Coordinates with PEX2/PEX10/PEX12 translocon
• Ensures proper cargo release

Complex Formation

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

• Peroxisomal β-oxidation handles very long-chain fatty acids
• Defective import reduces metabolic capacity
• Lipid accumulation in neurons

• 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

• 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

• 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)

• 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

• Enhance peroxisome function
• Bypass import deficits

• Gene therapy with metabolic support
• Antioxidant therapy

Challenges

Peroxisomal 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

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

Pathway Diagram

The following diagram shows the key molecular relationships involving pex14 discovered through SciDEX knowledge graph analysis:

Pathway Diagram

The following diagram shows the key molecular relationships involving PEX14 (Peroxisome Biogenesis Factor 14) discovered through SciDEX knowledge graph analysis: