COX5B: Cytochrome c Oxidase Subunit 5B
Mitochondrial Complex IV Nuclear-Encoded Subunit
Gene Information Card
| Symbol | COX5B |
|---|---|
| Full Name | cytochrome c oxidase subunit 5B |
| Gene Type | protein coding |
| Chromosomal Location | 2q11.2 |
| NCBI Gene ID | 1329 ncbi.nlm.nih.gov/gene/1329 |
| Ensembl ID | ENSG00000115944 |
| UniProt ID | P10606 |
| OMIM ID | 123866 |
| HGNC ID | 2269 |
| Aliases | COXVB, COX5B, cytochrome c oxidase subunit Vb |
Description
COX5B (cytochrome c oxidase subunit 5B) is a nuclear gene encoding a subunit of cytochrome c oxidase (Complex IV), the terminal enzyme of the mitochondrial electron transport chain. This subunit is essential for the assembly and function of the holoenzyme, which catalyzes the reduction of oxygen to water and couples this reaction to proton translocation across the inner mitochondrial membrane.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Mitochondrial complex IV deficiency | Loss-of-function mutations in COX5B impair complex IV assembly and activity, leading to defective oxidative phosphorylation. | ClinVar, OMIM |
| Leigh syndrome | Biallelic pathogenic variants in COX5B have been reported in patients with Leigh syndrome, a severe neurodegenerative disorder. | OMIM #123866, PubMed |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Heart | 48.2 | High |
| Skeletal muscle | 35.1 | High |
| Liver | 22.4 | Medium |
| Brain | 18.7 | Medium |
| Kidney | 15.3 | Medium |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK293 | 42.5 | High expression |
| HeLa | 38.1 | High expression |
| HepG2 | 29.6 | Moderate expression |
| K562 | 21.3 | Moderate expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.154C>T (p.Arg52Trp) | Missense | Rare | Loss of function; reduced complex IV activity |
| c.287_288del (p.Leu96Profs*19) | Frameshift | Rare | Loss of function; truncated protein |
| c.1A>G (p.Met1?) | Start loss | Rare | Loss of function; no translation initiation |
Mutation functional classification
Loss of Function (LOF)
Pathogenic variants in COX5B typically result in loss of function, leading to mitochondrial complex IV deficiency.
Gain of Function (GOF)
No gain-of-function mutations reported for COX5B.
Dominant Negative (DN)
No dominant-negative mutations reported for COX5B.
View complete mutation data：
Gene Ontology (GO)
| • cytochrome-c oxidase activity (GO:0004129) | • mitochondrial inner membrane (GO:0005743) |
| • integral component of membrane (GO:0016021) | • oxidative phosphorylation (GO:0006119) |
| • respiratory electron transport chain (GO:0022904) |
Pathways
• KEGG: hsa00190 - Oxidative phosphorylation
• Reactome: R-HSA-611105 - Respiratory electron transport
• Reactome: R-HSA-163200 - Formation of ATP by chemiosmotic coupling
Protein Summary
COX5B is a 129-amino acid protein (14.2 kDa) localized to the mitochondrial inner membrane. It is one of the nuclear-encoded subunits of cytochrome c oxidase (Complex IV). The protein contains a conserved COX5B domain and is required for the structural integrity and catalytic activity of the holoenzyme. It interacts with other subunits to form the copper center and facilitate electron transfer from cytochrome c to oxygen.
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