CYB5A
Cytochrome b5 type A (microsomal)
Gene Information Card
| Symbol | CYB5A |
|---|---|
| Full Name | Cytochrome b5 type A (microsomal) |
| Gene Type | protein-coding |
| Chromosomal Location | 18q22.3 |
| NCBI Gene ID | 1528 ncbi.nlm.nih.gov/gene/1528 |
| Ensembl ID | ENSG00000166347 |
| UniProt ID | P00167 |
| OMIM ID | 250790 |
| HGNC ID | 2573 |
| Aliases | CYB5, MCB5, MGC119984, MGC119985 |
Description
CYB5A encodes cytochrome b5, a membrane-bound hemoprotein that functions as an electron carrier for several membrane-bound oxygenases. It is involved in fatty acid desaturation, cholesterol biosynthesis, and methemoglobin reduction. Mutations in CYB5A cause type IV hereditary methemoglobinemia.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Methemoglobinemia, type IV | Loss-of-function mutations in CYB5A impair reduction of methemoglobin to hemoglobin, leading to elevated methemoglobin levels and cyanosis. | ClinVar, OMIM #250790 |
| Apparent aldosterone deficiency | Defective cytochrome b5 reduces 18-hydroxylase activity in adrenal steroidogenesis, causing salt-wasting and hypotension. | OMIM #250790 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 27.4 | High |
| Adrenal gland | 18.2 | Medium |
| Kidney | 12.1 | Medium |
| Heart | 8.5 | Medium |
| Brain | 5.3 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HepG2 | 32.1 | Hepatocellular carcinoma cell line |
| HEK293 | 15.6 | Embryonic kidney cells |
| K562 | 9.8 | Chronic myelogenous leukemia |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.98C>T (p.Thr33Met) | Missense | Rare | Reduced heme binding; associated with methemoglobinemia |
| c.200G>A (p.Arg67His) | Missense | Rare | Impaired electron transfer; pathogenic in ClinVar |
| c.1A>G (p.Met1Val) | Start loss | Very rare | Loss of translation initiation; likely pathogenic |
Mutation functional classification
Loss of Function (LOF)
Missense and start-loss mutations reduce or abolish cytochrome b5 electron transfer activity, leading to methemoglobinemia.
Gain of Function (GOF)
Not reported.
Dominant Negative (DN)
Not reported.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Fatty acid desaturation (Reactome: R-HSA-8978868)
• Methemoglobin reduction (Reactome: R-HSA-2161200)
• Cytochrome b5 electron transfer (KEGG: map00190)
Protein Summary
Cytochrome b5 type A is a 134-amino acid hemoprotein anchored to the endoplasmic reticulum membrane via a C-terminal transmembrane domain. It contains a heme-binding domain that transfers electrons to cytochrome P450 enzymes, stearoyl-CoA desaturase, and methemoglobin reductase. The protein is essential for lipid metabolism, drug detoxification, and red blood cell homeostasis.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| CYB5A Knockout HEK293 Cell Line | EDJ-KQ4389 | Human | 1528 | Details Get a Quote |
| CYB5A Knockout HeLa Cell Line | EDJ-KQ25636 | Human | 1528 | Details Get a Quote |
| CYB5A Knockout A-549 Cell Line | EDJ-KQ26912 | Human | 1528 | Details Get a Quote |
| CYB5A Knockout HCT 116 Cell Line | EDJ-KQ26913 | Human | 1528 | Details Get a Quote |
Displaying Records 1 To 4 Of 4 Records
