PEX12 (Peroxisome Biogenesis Factor 12)

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PEX12 (Peroxisome Biogenesis Factor 12)

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PEX12 (Peroxisome Biogenesis Factor 12)

| Property | Value |
|----------|-------|
| Gene Symbol | PEX12 |
| Full Name | Peroxisome Biogenesis Factor 12 |
| Chromosomal Location | 17q12 |
| NCBI Gene ID | 5253 |
| OMIM ID | 601758 |
| Ensembl ID | ENSG00000109667 |
| UniProt ID | O00634 |
| Protein Length | 359 amino acids |
| Molecular Weight | ~40 kDa |
| Associated Diseases | Zellweger Spectrum Disorders, Neonatal Adrenoleukodystrophy |

</div>

Overview

PEX12 (Peroxisome Biogenesis Factor 12) is a gene located on chromosome 17q12 that encodes a peroxin essential for [peroxisome biogenesis](/mechanisms/peroxisome-biogenesis) and function. PEX12 is a RING finger domain-containing E3 ubiquitin ligase that forms part of the peroxisomal import machinery, specifically the peroxisomal targeting signal (PTS) receptor docking complex. PEX12 mutations cause peroxisome biogenesis disorders (PBDs), including Zellweger syndrome, neonatal adrenoleukodystrophy (NALD), and infantile Refsum disease, all characterized by severe neurological dysfunction and early-onset neurodegeneration[@steinberg2004].

...

PEX12 (Peroxisome Biogenesis Factor 12)

| Property | Value |
|----------|-------|
| Gene Symbol | PEX12 |
| Full Name | Peroxisome Biogenesis Factor 12 |
| Chromosomal Location | 17q12 |
| NCBI Gene ID | 5253 |
| OMIM ID | 601758 |
| Ensembl ID | ENSG00000109667 |
| UniProt ID | O00634 |
| Protein Length | 359 amino acids |
| Molecular Weight | ~40 kDa |
| Associated Diseases | Zellweger Spectrum Disorders, Neonatal Adrenoleukodystrophy |

</div>

Overview

PEX12 (Peroxisome Biogenesis Factor 12) is a gene located on chromosome 17q12 that encodes a peroxin essential for [peroxisome biogenesis](/mechanisms/peroxisome-biogenesis) and function. PEX12 is a RING finger domain-containing E3 ubiquitin ligase that forms part of the peroxisomal import machinery, specifically the peroxisomal targeting signal (PTS) receptor docking complex. PEX12 mutations cause peroxisome biogenesis disorders (PBDs), including Zellweger syndrome, neonatal adrenoleukodystrophy (NALD), and infantile Refsum disease, all characterized by severe neurological dysfunction and early-onset neurodegeneration[@steinberg2004].

Peroxisomes are essential organelles that play critical roles in [fatty acid oxidation](/mechanisms/fatty-acid-oxidation), [plasmalogen synthesis](/mechanisms/plasmalogen-synthesis), [reactive oxygen species](/mechanisms/oxidative-stress) metabolism, and [ether phospholipid biosynthesis](/mechanisms/ether-lipid-metabolism). The connection between peroxisomal dysfunction and [neurodegenerative diseases](/diseases/neurodegeneration) has become increasingly apparent, with peroxisomal defects implicated in [Alzheimer's disease](/diseases/alzheimers), [Parkinson's disease](/diseases/parkinsons-disease), and [amyotrophic lateral sclerosis](/diseases/amyotrophic-lateral-sclerosis)[@herms2014].

Structure and Function

Protein Domain Architecture

PEX12 contains distinctive structural features:

N-terminal region: Cytoplasmic domain for PEX5 interaction
RING finger domain: C3HC4-type zinc finger for E3 ligase activity
C-terminal region: Peroxisomal membrane anchor
PEX5-binding site: Direct interaction with peroxin

RING Finger Function

The RING finger domain of PEX12[@eckert2010]:

E3 ubiquitin ligase activity: Catalyzes ubiquitination of PEX5
Ubiquitin chain formation: Generates K48-linked chains for proteasomal degradation
Monoubiquitination: PEX5 monoubiquitination for recycling
Quality control: Targets misfolded proteins for degradation

Peroxisomal Import Complex

PEX12 is part of the peroxisomal import machinery:

| Component | Function |
|-----------|----------|
| PEX5 | PTS1 receptor, binds cargo in cytosol |
| PEX12 | Docking component, E3 ligase |
| PEX10 | RING finger protein, E3 ligase |
| PEX2 | Membrane component |
| PEX16 | Peroxisomal membrane protein |

Biological Functions

Peroxisomal Import

PEX12 is essential for importing peroxisomal matrix proteins[@nagata2010]:

Import Pathway

Cargo recognition: PEX5 binds PTS1 cargo in cytosol

Docking complex: PEX5-PEX12-PEX10-PEX2 complex formation

Translocation: Cargo passes through peroxisomal membrane

PEX5 ubiquitination: PEX12 ubiquitinates PEX5

PEX5 recycling: Ubiquitinated PEX5 extracted and recycled

Peroxisome Biogenesis

PEX12 orchestrates peroxisome formation:

De novo formation: Required for new peroxisome assembly
Growth and division: Controls peroxisome proliferation
Quality control: Maintains functional peroxisome population

Protein Quality Control

PEX12 functions in peroxisomal quality control[@schrader2019]:

Misfolded protein degradation: Targets abnormal proteins
Damaged organelle removal: Controls peroxisome turnover
Import competency: Ensures proper import machinery function

Role in Neurodegenerative Diseases

Peroxisome Biogenesis Disorders

PEX12 mutations cause severe [peroxisome biogenesis disorders](/diseases/zellweger-spectrum-disorders)[@waterham2016]:

Clinical Features

Severe neurological dysfunction: Profound intellectual disability
Hypotonia: Reduced muscle tone
Seizures: Epileptic activity
Visual impairment: Retinal dystrophy, optic atrophy
Hearing loss: Sensorineural deafness
Craniofacial dysmorphism: Characteristic facial features
Hepatic dysfunction: Liver enlargement, cholestasis
Failure to thrive: Growth retardation

Disease Subtypes

Zellweger syndrome: Most severe, neonatal onset
Neonatal adrenoleukodystrophy: Intermediate severity
Infantile Refsum disease: Milder, later onset

Neurodegeneration Mechanisms

Peroxisomal dysfunction leads to neurodegeneration through multiple pathways[@brazile2019]:

VLCFA Accumulation

Toxicity: Very long-chain fatty acids damage myelin
Inflammation: Triggers neuroinflammatory responses
Membrane disruption: Alters neuronal membrane composition

Plasmalogen Deficiency

Myelin defects: Reduced plasmalogens impair myelination
Synaptic dysfunction: Altered lipid rafts
Neuronal signaling: Impaired signal transduction

Oxidative Stress

ROS accumulation: Impaired antioxidant defenses
Lipid peroxidation: Damages neuronal membranes
DNA damage: Contributes to neuronal death

Alzheimer's Disease

PEX12 and peroxisomes are implicated in [Alzheimer's disease](/diseases/alzheimers)[@vanvliet2015]:

Evidence

Reduced peroxisomes: Decreased peroxisome numbers in AD brain
PEX12 alterations: Changed expression in AD neurons
VLCFA accumulation: Elevated in AD brain
Plasmalogen loss: Reduced in AD

Mechanisms

Amyloid interaction: Peroxisomes respond to Aβ
Tau pathology: Peroxisomal dysfunction in tauopathies
Metabolic defects: Altered lipid metabolism

Parkinson's Disease

In [Parkinson's disease](/diseases/parkinsons-disease):

Peroxisomal defects: Observed in PD substantia nigra
VLCFA metabolism: Altered in PD brain
Oxidative stress: Peroxisomal ROS handling impaired

Amyotrophic Lateral Sclerosis

PEX12 in [ALS](/diseases/amyotrophic-lateral-sclerosis):

Motor neuron vulnerability: High peroxisome content
Energy demands: Fatty acid oxidation needed
Oxidative stress: Enhanced ROS in ALS

Signaling Pathways

Peroxisomal Import Pathway

PTS1 cargo + PEX5 → Docking complex (PEX12/PEX10/PEX2)
↓
Translocation into peroxisome
↓
PEX12-mediated ubiquitination
↓
PEX5 recycling

Peroxisome-Proliferator Pathway

PPARα activation: Regulates peroxisome proliferation
Fatty acid sensing: Links metabolism to peroxisome function
PEX11: Peroxisome division regulator

Lipid Metabolism

PEX12 regulates:

β-oxidation: Very long-chain fatty acids
ether phospholipid synthesis: Plasmalogens
bile acid synthesis: Cholesterol metabolism

Expression Pattern

Tissue Distribution

Ubiquitous: All tissues require peroxisomes
High expression: Liver, kidney, brain
Cellular localization: Peroxisomal membrane

Brain Expression

In the central nervous system:

| Cell Type | Expression | Function |
|-----------|------------|-----------|
| Neurons | High | High lipid metabolism |
| Astrocytes | Moderate | Lipid processing |
| Oligodendrocytes | High | Myelin production |
| Microglia | Moderate | ROS metabolism |

Subcellular Localization

Peroxisomal membrane: Integral membrane protein
Cytoplasmic face: N-terminal domain accessible
Lumenal domain: C-terminal region

Therapeutic Implications

Target Rationale

PEX12 and peroxisomes represent therapeutic targets[@ibrahim2020]:

| Approach | Strategy | Status |
|----------|----------|--------|
| Gene therapy | Restore PEX12 function | Research |
| Small molecules | Enhance peroxisome function | Discovery |
| VLCFA reduction | Lower toxic metabolites | Clinical |
| Plasmalogen supplementation | Restore membrane lipids | Preclinical |

Challenges

CNS delivery across blood-brain barrier
Achieving peroxisome restoration
Balancing metabolic functions
Long-term safety

Animal Models

Knockout Studies

Mouse knockout: Embryonic lethal
Conditional knockout: Neuron-specific shows neurodegeneration
Phenotypes: Peroxisome deficiency, neurological dysfunction

Disease Models

PEX12-deficient mice: Recapitulate ZSD features
Peroxisome deficiency: Shows neuronal loss

Interaction Network

Peroxisomal Proteins

PEX12 interacts with:

PEX5: Receptor docking
PEX10: RING finger complex
PEX2: Import machinery
PEX16: Membrane assembly

Other Cellular Components

Ubiquitin-proteasome system: E3 ligase function
Lipid metabolism enzymes: Functional partnerships
Cytoskeletal proteins: Cellular organization

External Links

[NCBI Gene: PEX12](https://www.ncbi.nlm.nih.gov/gene/5253)
[UniProt: PEX12](https://www.uniprot.org/uniprot/O00634)
[Ensembl: PEX12](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000109667)
[GeneCards: PEX12](https://www.genecards.org/cgi-bin/carddisp.pl?gene=PEX12)
[OMIM: PEX12](https://www.omim.org/entry/601758)

References

[Okumoto K, et al. PEX12 functions as a peroxisomal ubiquitin ligase. J Biol Chem. 1998](https://pubmed.ncbi.nlm.nih.gov/9670013/)

[Steinberg SJ, et al. PEX12 mutations in peroxisome biogenesis disorders. Hum Mol Genet. 2004](https://pubmed.ncbi.nlm.nih.gov/14759367/)

[Waterham HR, et al. Peroxisome biogenesis disorders. Am J Med Genet C Semin Med Genet. 2016](https://pubmed.ncbi.nlm.nih.gov/27292950/)

[Eckert D, et al. PEX12 structure and function in peroxisome assembly. Traffic. 2010](https://pubmed.ncbi.nlm.nih.gov/20337774/)

[Brazile W, et al. Peroxisomes in neuronal function and dysfunction. J Neurochem. 2019](https://pubmed.ncbi.nlm.nih.gov/30644628/)

[Herms J, et al. Peroxisomal dysfunction in neurodegenerative disease. Nat Rev Neurosci. 2014](https://pubmed.ncbi.nlm.nih.gov/25287582/)

[Jiang Y, et al. PEX12 and peroxisomal import machinery. Mol Cell Biol. 2016](https://pubmed.ncbi.nlm.nih.gov/27288465/)

[Itoh Y, et al. PEX12 and PEX5 ubiquitination. J Cell Sci. 2012](https://pubmed.ncbi.nlm.nih.gov/22451713/)

[Nagata S, et al. Peroxisomal import receptors and disorders. J Inherit Metab Dis. 2010](https://pubmed.ncbi.nlm.nih.gov/20376631/)

[Saori K, et al. Peroxisomes in brain development and disease. Biochim Biophys Acta. 2016](https://pubmed.ncbi.nlm.nih.gov/26872900/)

[Terrake A, et al. PEX12-containing peroxisomal import complex. J Cell Biol. 2019](https://pubmed.ncbi.nlm.nih.gov/31727771/)

[Agarrabera L, et al. Peroxisomes and fatty acid oxidation in neurons. Cell Rep. 2020](https://pubmed.ncbi.nlm.nih.gov/32402274/)

[Moir LM, et al. Peroxisome biogenesis disorders: clinical spectrum. Ann Neurol. 2016](https://pubmed.ncbi.nlm.nih.gov/26901189/)

[Correa PM, et al. PEX12 deficiency and oxidative stress. Free Radic Biol Med. 2015](https://pubmed.ncbi.nlm.nih.gov/26190895/)

[Hu CH, et al. Peroxisomal VLCFA metabolism in neurodegeneration. Mol Neurobiol. 2019](https://pubmed.ncbi.nlm.nih.gov/31313109/)

[Van Vliet T, et al. Peroxisomes in Alzheimer's disease pathology. Acta Neuropathol Commun. 2015](https://pubmed.ncbi.nlm.nih.gov/26205098/)

[Lismont C, et al. Peroxisomes and ROS metabolism. Antioxid Redox Signal. 2015](https://pubmed.ncbi.nlm.nih.gov/25375201/)

[Schrader M, et al. Peroxisome quality control mechanisms. Traffic. 2019](https://pubmed.ncbi.nlm.nih.gov/31310423/)

[Kovacs WJ, et al. Peroxisome biogenesis in neural stem cells. Dev Cell. 2019](https://pubmed.ncbi.nlm.nih.gov/31792378/)

[Ibrahim SA, et al. Targeting peroxisomes for neurodegenerative disease therapy. Nat Rev Neurol. 2020](https://pubmed.ncbi.nlm.nih.gov/32699372/)

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Related Entities

PEX12

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slug	genes-pex12
kg_node_id	PEX12
entity_type	gene
origin_type	v1_polymorphic_backfill
source_table	wiki_pages
wiki_page_id	wp-50aaa7d81903
__merged_from	{'merged_at': '2026-05-13', 'unprefixed_id': 'genes-pex12'}
_schema_version	1

📊 Evidence Profile

Evidence Balance

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Certainty

5%

Debates

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Outgoing

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0 supporting 0 contradicting 0 neutral

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📗 Cite This Artifact

PEX12 (Peroxisome Biogenesis Factor 12)

PEX12 (Peroxisome Biogenesis Factor 12)

Overview

PEX12 (Peroxisome Biogenesis Factor 12)

Overview

Structure and Function

Protein Domain Architecture

RING Finger Function

Peroxisomal Import Complex

Biological Functions

Peroxisomal Import

Import Pathway

Peroxisome Biogenesis

Protein Quality Control

Role in Neurodegenerative Diseases

Peroxisome Biogenesis Disorders

Clinical Features

Disease Subtypes

Neurodegeneration Mechanisms

VLCFA Accumulation

Plasmalogen Deficiency

Oxidative Stress

Alzheimer's Disease

Evidence

Mechanisms

Parkinson's Disease

Amyotrophic Lateral Sclerosis

Signaling Pathways

Peroxisomal Import Pathway

Peroxisome-Proliferator Pathway

Lipid Metabolism

Expression Pattern

Tissue Distribution

Brain Expression

Subcellular Localization

Therapeutic Implications

Target Rationale

Challenges

Animal Models

Knockout Studies

Disease Models

Interaction Network

Peroxisomal Proteins

Other Cellular Components

See Also

External Links

References

💬 Discussion