COQ3: Coenzyme Q3, Methyltransferase
Essential enzyme in coenzyme Q10 biosynthesis and mitochondrial function
Gene Information Card
| Symbol | COQ3 |
|---|---|
| Full Name | Coenzyme Q3, methyltransferase |
| Gene Type | protein-coding |
| Chromosomal Location | 6q16.2 |
| NCBI Gene ID | 51805 ncbi.nlm.nih.gov/gene/51805 |
| Ensembl ID | ENSG00000112210 |
| UniProt ID | Q9H4N1 |
| OMIM ID | 605196 |
| HGNC ID | 25222 |
| Aliases | DHHB, bA9819.1, CGI-121, COQ3_HUMAN |
Description
COQ3 encodes a methyltransferase required for the biosynthesis of coenzyme Q10 (ubiquinone), a key component of the mitochondrial electron transport chain. The enzyme catalyzes the O-methylation of 3,4-dihydroxy-5-polyprenylbenzoate and 3-demethylubiquinone-9, essential steps in CoQ10 production. Mutations in COQ3 cause primary coenzyme Q10 deficiency, leading to mitochondrial dysfunction and multisystem disorders.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Primary coenzyme Q10 deficiency, type 6 | Loss-of-function mutations impair CoQ10 biosynthesis, reducing mitochondrial ATP production and increasing oxidative stress. | ClinVar, OMIM #614650 |
| Mitochondrial encephalopathy | Deficient CoQ10 disrupts respiratory chain complex I+III and II+III activities, causing neurological symptoms. | NCBI Gene, OMIM |
| Nephrotic syndrome | CoQ10 deficiency in renal cells leads to podocyte injury and proteinuria. | ClinVar, literature |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Heart | 12.5 | Medium |
| Skeletal muscle | 10.8 | Medium |
| Liver | 9.2 | Medium |
| Kidney | 8.7 | Medium |
| Brain | 6.4 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK293 | 14.3 | High expression |
| HeLa | 11.1 | Medium expression |
| HepG2 | 9.8 | Medium expression |
| K562 | 7.5 | Low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.683G>A (p.Arg228His) | Missense | Rare | Impaired methyltransferase activity; associated with CoQ10 deficiency |
| c.424C>T (p.Arg142*) | Nonsense | Rare | Premature truncation; loss of function |
| c.1A>G (p.Met1?) | Start loss | Rare | No protein production; severe deficiency |
Mutation functional classification
Loss of Function (LOF)
Missense and nonsense mutations reduce or abolish methyltransferase activity, leading to CoQ10 deficiency.
Gain of Function (GOF)
No gain-of-function mutations reported.
Dominant Negative (DN)
No dominant-negative mutations reported.
View complete mutation data：
Gene Ontology (GO)
| • 2-polyprenyl-6-methoxyphenol hydroxylase activity (GO:0008425) | • 3-demethylubiquinone-9 3-O-methyltransferase activity (GO:0008686) |
| • mitochondrial inner membrane (GO:0005743) | • ubiquinone biosynthetic process (GO:0006744) |
| • mitochondrion (GO:0005739) |
Pathways
• Ubiquinone biosynthesis (KEGG: hsa00130)
• Metabolic pathways (KEGG: hsa01100)
• Mitochondrial electron transport
• ubiquinol to cytochrome c (Reactome: R-HSA-611105)
Protein Summary
COQ3 is a 369-amino-acid methyltransferase localized to the mitochondrial inner membrane. It catalyzes two O-methylation steps in the CoQ10 biosynthesis pathway. The protein contains a conserved methyltransferase domain and is essential for proper mitochondrial function. Defects in COQ3 lead to primary CoQ10 deficiency, a rare autosomal recessive disorder characterized by encephalopathy, nephropathy, and myopathy.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| COQ3 Knockout HEK293 Cell Line | EDJ-KQ11225 | Human | 51805 | Details Get a Quote |
| COQ3 Knockout A-549 Cell Line | EDJ-KQ39295 | Human | 51805 | Details Get a Quote |
| COQ3 Knockout HCT 116 Cell Line | EDJ-KQ39296 | Human | 51805 | Details Get a Quote |
| COQ3 Knockout HeLa Cell Line | EDJ-KQ39297 | Human | 51805 | Details Get a Quote |
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