PEX12 (Peroxin-12) is a RING finger peroxisomal membrane protein that functions as an E3 ubiquitin ligase essential for peroxisome biogenesis. It plays a critical role in peroxisomal matrix protein import and receptor recycling.
| Property | Value |
|----------|-------|
| UniProt ID | O00312 |
| Gene | PEX12 |
| Alternative Names | Peroxin-12, PEX12L |
| Molecular Weight | ~39 kDa |
| Subcellular Localization | Peroxisomal membrane |
| Protein Family | RING finger protein family |
| PDB Structures | Not determined |
PEX12 contains:
- RING finger domain: C3HC4-type zinc finger at C-terminus for E3 ubiquitin ligase activity
- Transmembrane domains: Three predicted TMDs for peroxisomal membrane anchoring
- N-terminal regulatory region: Interacts with PEX5 and PEX10
The RING domain faces the cytoplasm and functions in ubiquitination of peroxisomal targeting receptors.
PEX12 is essential for:
- Peroxisomal matrix protein import via PTS1 pathway
- PEX5 receptor ubiquitination and recycling
- Quality control of peroxisomal proteins
- Formation of peroxisomal ghosts (membrane structures without matrix proteins)
- E3 ubiquitin ligase activity
- Targets PEX5 for monoubiquitination (recycling) and polyubiquitination (degradation)
- Cooperates with PEX10 and PEX2 in the peroxisomal ubiquitination complex
- Peroxisome proliferation and maintenance
- Regulation of peroxisome number and size
- Response to cellular metabolic demands
PEX12 mutations cause:
- Zellweger syndrome (severe)
- Neonatal adrenoleukodystrophy (NALD)
- Infantile Refsum disease
Neurological manifestations include:
- Severe developmental delay
- Characteristic facial dysmorphism
- Hypotonia and areflexia
- Visual impairment (cataracts, optic atrophy)
- Hearing loss
- Adult Refsum disease (ARD)
- ZSS-like phenotypes with later onset
- Peroxisomal dysfunction contributes to AD pathogenesis
- Impaired peroxisome biogenesis in AD neurons
- Accumulation of VLCFAs and phytanic acid
- Reduced plasmalogens (myelin lipids)
- Peroxisomal function in dopaminergic neuron survival
- PEX12 variants associated with PD risk in some populations
- Pexophagy defects in PD models
- Gene therapy approaches (AAV-PEX12)
- Pharmacological activation of peroxisome proliferation
- Substrate reduction therapy for VLCFAs
- Antioxidant therapy
- Correcting membrane protein function
- Achieving proper peroxisomal targeting
- Managing immune response to foreign proteins
| Variant |
Effect |
Disease Association |
| Y404X |
Truncated protein |
Severe ZSD |
| R120Q |
Missense |
Moderate ZSD |
| C300G |
Missense |
Variable |