PEX5
Domain
The TPR repeats mediate interaction with proteins containing a C-terminal PTS1-type tripeptide peroxisomal targeting signal (SKL-type).
The WxxxF/Y motifs mediate interaction with PEX14, promoting association with the PEX13-PEX14 docking complex.
The amphipathic helix 1 and 2 (AH1 and AH2, respectively) are required for PEX5 retrotranslocation and recycling (By similarity). AH2 mediates interaction with lumenal side of the PEX2-PEX10-PEX12 ligase complex, while AH1 is required for extraction from peroxisomal membrane by the PEX1-PEX6 AAA ATPase complex (By similarity).
Function
Receptor that mediates peroxisomal import of proteins containing a C-terminal PTS1-type tripeptide peroxisomal targeting signal (SKL-type) (PubMed:11101887, PubMed:11336669, PubMed:12456682, PubMed:16314507, PubMed:17157249, PubMed:17428317, PubMed:21976670, PubMed:26344566, PubMed:7706321, PubMed:7719337, PubMed:7790377). Binds to cargo proteins containing a PTS1 peroxisomal targeting signal in the cytosol, and translocates them into the peroxisome matrix by passing through the PEX13-PEX14 docking complex along with cargo proteins (PubMed:12456682, PubMed:17157249, PubMed:21976670, PubMed:26344566). PEX5 receptor is then retrotranslocated into the cytosol, leading to release of bound cargo in the peroxisome matrix, and reset for a subsequent peroxisome import cycle (PubMed:11336669, PubMed:24662292).
Isoform 1
In addition to promoting peroxisomal translocation of proteins containing a PTS1 peroxisomal targeting signal, mediates peroxisomal import of proteins containing a C-terminal PTS2-type peroxisomal targeting signal via its interaction with PEX7 (PubMed:11336669, PubMed:11546814, PubMed:25538232, PubMed:33389129, PubMed:9668159). Interaction with PEX7 only takes place when PEX7 is associated with cargo proteins containing a PTS2 peroxisomal targeting signal (PubMed:25538232). PEX7 along with PTS2-containing cargo proteins are then translocated through the PEX13-PEX14 docking complex together with PEX5 (PubMed:25538232).
Isoform 2
Does not mediate translocation of peroxisomal import of proteins containing a C-terminal PTS2-type peroxisomal targeting signal.
Involvement in disease
Peroxisome biogenesis disorder 2A
PBD2A
A fatal peroxisome biogenesis disorder belonging to the Zellweger disease spectrum and characterized clinically by severe neurologic dysfunction with profound psychomotor retardation, severe hypotonia and neonatal seizures, craniofacial abnormalities, liver dysfunction, and biochemically by the absence of peroxisomes. Additional features include cardiovascular and skeletal defects, renal cysts, ocular abnormalities, and hearing impairment. Most severely affected individuals with the classic form of the disease (classic Zellweger syndrome) die within the first year of life.
None
The disease is caused by variants affecting the gene represented in this entry.
Peroxisome biogenesis disorder 2B
PBD2B
A peroxisome biogenesis disorder that includes neonatal adrenoleukodystrophy (NALD) and infantile Refsum disease (IRD), two milder manifestations of the Zellweger disease spectrum. The clinical course of patients with the NALD and IRD presentation is variable and may include developmental delay, hypotonia, liver dysfunction, sensorineural hearing loss, retinal dystrophy and vision impairment. Children with the NALD presentation may reach their teens, while patients with the IRD presentation may reach adulthood. The clinical conditions are often slowly progressive in particular with respect to loss of hearing and vision. The biochemical abnormalities include accumulation of phytanic acid, very long chain fatty acids (VLCFA), di- and trihydroxycholestanoic acid and pipecolic acid.
None
The disease is caused by variants affecting the gene represented in this entry.
Rhizomelic chondrodysplasia punctata 5
RCDP5
A form of rhizomelic chondrodysplasia punctata, a disease characterized by severely disturbed endochondral bone formation, rhizomelic shortening of femur and humerus, vertebral disorders, dwarfism, cataract, cutaneous lesions, facial dysmorphism, and severe intellectual disability with spasticity.
None
The disease is caused by variants affecting the gene represented in this entry.
Post-translational modifications
Monoubiquitinated at Cys-11 by PEX2 during PEX5 passage through the retrotranslocation channel (By similarity). Cys-11 monoubiquitination acts as a recognition signal for the PEX1-PEX6 complex and is required for PEX5 extraction and export from peroxisomes (PubMed:29884772). Monoubiquitination at Cys-11 is removed by USP9X in the cytosol, resetting PEX5 for a subsequent import cycle (PubMed:22371489). When PEX5 recycling is compromised, polyubiquitinated by PEX10 during its passage through the retrotranslocation channel, leading to its degradation (By similarity). Monoubiquitination at Lys-472 by TRIM37 promotes its stability by preventing its polyubiquitination and degradation by the proteasome (PubMed:28724525). Ubiquitination at Lys-527 is not mediated by the PEX2-PEX10-PEX12 ligase complex and is not related to PEX5 recycling (PubMed:24662292). Monoubiquitinated at Lys-209 by PEX2 following phosphorylation by ATM in response to starvation or reactive oxygen species (ROS), leading to PEX5 recognition by p62/SQSTM1 and induction of pexophagy (PubMed:26344566, PubMed:27597759).
Phosphorylated at Ser-141 by ATM in response to reactive oxygen species (ROS), promoting monoubiquitination at Lys-209 and induction of pexophagy.
Sequence Similarities
Belongs to the peroxisomal targeting signal receptor family.
Tissue Specificity
Detected in heart, brain, placenta, lung, liver, skeletal muscle, kidney and pancreas.
Cellular localization
- Cytoplasm
- Cytosol
- Peroxisome matrix
- Cycles between the cytosol and the peroxisome matrix (PubMed:11336669, PubMed:16314507). Following binding to cargo proteins containing a PTS1 peroxisomal targeting signal in the cytosol, recruited to the docking complex, composed of PEX13 and PEX14, leading to translocation into the peroxisome matrix along with cargo proteins (By similarity). Export and recycling to the cytosol is initiated by binding to the PEX2-PEX10-PEX12 ligase complex via its unstructured N-terminus that inserts into the ligase pore and emerges in the cytosol (By similarity). Cys-11 of PEX5 is then monoubiquitinated, promoting its extraction from peroxisomal membrane by the PEX1-PEX6 AAA ATPase complex (PubMed:16314507, PubMed:19208625, PubMed:24118911, PubMed:29884772). Extraction is accompanied by unfolding of the TPR repeats and release of bound cargo in the peroxisome matrix (By similarity). The TPR repeats refold in the cytosol and ubiquitination is removed by deubiquitinating enzymes, resetting PEX5 for a subsequent import cycle (By similarity).
Alternative names
PXR1, PEX5, Peroxisomal targeting signal 1 receptor, PTS1 receptor, PTS1R, PTS1-BP, Peroxin-5, Peroxisomal C-terminal targeting signal import receptor, Peroxisome receptor 1