CYB5R4
Cytochrome b5 reductase 4
Gene Information Card
| Symbol | CYB5R4 |
|---|---|
| Full Name | Cytochrome b5 reductase 4 |
| Gene Type | Protein coding |
| Chromosomal Location | 6q14.1 |
| NCBI Gene ID | 51167 ncbi.nlm.nih.gov/gene/51167 |
| Ensembl ID | ENSG00000112294 |
| UniProt ID | Q7L1T6 |
| OMIM ID | 613204 |
| HGNC ID | 25098 |
| Aliases | NCB5OR, b5R.4, DJ149A16.6 |
Description
CYB5R4 encodes a member of the cytochrome b5 reductase family, a flavoprotein that uses NADH as an electron donor to reduce cytochrome b5. This enzyme is involved in electron transport, fatty acid desaturation, cholesterol biosynthesis, and drug metabolism. It is localized to the endoplasmic reticulum and mitochondria.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Methemoglobinemia, type IV (suspected) | Deficiency in CYB5R4 may impair NADH-dependent reduction of methemoglobin, leading to accumulation of oxidized hemoglobin. | Limited; inferred from functional homology with CYB5R3 (OMIM #250800) and case reports. |
| Cancer (various) | Altered expression of CYB5R4 may affect oxidative stress response and drug metabolism in tumor cells. | COSMIC database reports somatic mutations in colorectal, lung, and breast cancers. |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 12.5 | Medium |
| Kidney | 8.3 | Medium |
| Heart | 6.1 | Low |
| Brain | 4.2 | Low |
| Testis | 3.8 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HepG2 | 10.2 | Hepatocellular carcinoma cell line |
| A549 | 7.5 | Lung adenocarcinoma cell line |
| MCF7 | 5.9 | Breast cancer cell line |
| HEK293 | 4.8 | Embryonic kidney cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G (p.Met1?) | Missense | <0.01% | Likely loss of start codon; predicted loss of function |
| c.287C>T (p.Thr96Ile) | Missense | 0.02% | Reduced enzymatic activity in vitro |
| c.512G>A (p.Arg171His) | Missense | 0.01% | Unknown functional effect |
Mutation functional classification
Loss of Function (LOF)
Mutations affecting the NADH-binding domain or catalytic residues (e.g., p.Met1?) are predicted to abolish reductase activity.
Gain of Function (GOF)
No gain-of-function mutations reported in CYB5R4.
Dominant Negative (DN)
No dominant-negative mutations documented.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Electron transport chain (mitochondrial)
• Fatty acid desaturation (REACT_111217)
• Cholesterol biosynthesis (REACT_602)
Protein Summary
CYB5R4 is a 34.5 kDa flavoprotein containing an FAD-binding domain and a NADH-binding domain. It localizes to the endoplasmic reticulum and mitochondria, where it transfers electrons from NADH to cytochrome b5. This activity supports fatty acid desaturation, cholesterol synthesis, and detoxification reactions. The protein is ubiquitously expressed with highest levels in liver and kidney.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| CYB5R4 Knockout HEK293 Cell Line | EDJ-KQ10958 | Human | 51167 | Details Get a Quote |
| CYB5R4 Knockout A-549 Cell Line | EDJ-KQ38763 | Human | 51167 | Details Get a Quote |
| CYB5R4 Knockout HCT 116 Cell Line | EDJ-KQ38764 | Human | 51167 | Details Get a Quote |
| CYB5R4 Knockout HeLa Cell Line | EDJ-KQ38765 | Human | 51167 | Details Get a Quote |
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