COQ2: Coenzyme Q2, Polyprenyltransferase
Key enzyme in coenzyme Q10 biosynthesis; associated with primary coenzyme Q10 deficiency and multiple system atrophy.
Gene Information Card
| Symbol | COQ2 |
|---|---|
| Full Name | Coenzyme Q2, polyprenyltransferase |
| Gene Type | Protein coding |
| Chromosomal Location | 4q21.23 |
| NCBI Gene ID | 27235 ncbi.nlm.nih.gov/gene/27235 |
| Ensembl ID | ENSG00000138684 |
| UniProt ID | Q96H96 |
| OMIM ID | 609825 |
| HGNC ID | 25223 |
| Aliases | CL640, PHB, COQ10D1, MSA1 |
Description
The COQ2 gene encodes polyprenyltransferase, an enzyme essential for the biosynthesis of coenzyme Q10 (ubiquinone), a critical component of the mitochondrial electron transport chain and a lipid-soluble antioxidant. Mutations in COQ2 cause primary coenzyme Q10 deficiency, a mitochondrial disorder with variable clinical manifestations including encephalopathy, nephropathy, and myopathy. Additionally, specific variants have been associated with increased risk for multiple system atrophy (MSA).
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Primary coenzyme Q10 deficiency 1 | Loss-of-function mutations impair CoQ10 biosynthesis, disrupting mitochondrial respiration and antioxidant defense. | OMIM #607426; ClinVar pathogenic variants |
| Multiple system atrophy (MSA) | Homozygous or compound heterozygous COQ2 variants (e.g., V393A) reduce CoQ10 levels, contributing to neurodegeneration. | PMID: 23314052; ClinVar risk allele |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Kidney | 12.3 | High |
| Liver | 8.7 | Medium |
| Heart | 7.1 | Medium |
| Brain | 5.4 | Low |
| Skeletal muscle | 4.2 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK 293 | 9.8 | Embryonic kidney cells |
| HepG2 | 8.1 | Liver carcinoma cells |
| K562 | 6.5 | Leukemia cells |
| SH-SY5Y | 5.0 | Neuroblastoma cells |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1178C>T (p.V393A) | Missense | 0.5% in East Asian populations | Reduced enzyme activity; risk factor for MSA |
| c.483G>A (p.W161*) | Nonsense | Rare | Loss of function; causes CoQ10 deficiency |
| c.890A>G (p.Y297C) | Missense | Rare | Impaired polyprenyltransferase activity |
Mutation functional classification
Loss of Function (LOF)
Nonsense and missense variants (e.g., p.W161*, p.Y297C) that reduce or abolish polyprenyltransferase activity, leading to CoQ10 deficiency.
Gain of Function (GOF)
No gain-of-function mutations reported for COQ2.
Dominant Negative (DN)
No dominant-negative mutations reported; COQ2 deficiency is typically autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
| • polyprenyltransferase activity (GO:0004659) | • ubiquinone biosynthetic process (GO:0006744) |
| • mitochondrion (GO:0005739) | • mitochondrial inner membrane (GO:0005743) |
Pathways
• Ubiquinone biosynthesis (KEGG: hsa00130)
• Mitochondrial electron transport chain (Reactome: R-HSA-611105)
Protein Summary
COQ2 encodes a 421-amino acid polyprenyltransferase localized to the mitochondrial inner membrane. The enzyme catalyzes the prenylation of 4-hydroxybenzoate, a key step in coenzyme Q10 biosynthesis. CoQ10 shuttles electrons from complexes I and II to complex III in the respiratory chain and acts as a membrane antioxidant. Structural studies indicate a transmembrane domain and a conserved active site. Defects in COQ2 lead to reduced CoQ10 levels, mitochondrial dysfunction, and oxidative stress.
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