CYC1: Cytochrome c1, Heme Protein, Mitochondrial
A critical component of mitochondrial Complex III in the electron transport chain, linked to nuclear-encoded mitochondrial complex III deficiency.
Gene Information Card
| Symbol | CYC1 |
|---|---|
| Full Name | Cytochrome c1, heme protein, mitochondrial |
| Gene Type | Protein coding |
| Chromosomal Location | 8q24.3 |
| NCBI Gene ID | 1537 ncbi.nlm.nih.gov/gene/1537 |
| Ensembl ID | ENSG00000158571 |
| UniProt ID | P08574 |
| OMIM ID | 123980 |
| HGNC ID | 2579 |
| Aliases | MC3DN6, UQCR4, cytochrome c-1 |
Description
CYC1 encodes cytochrome c1, a heme-containing subunit of mitochondrial respiratory chain Complex III (ubiquinol-cytochrome c reductase). This protein transfers electrons from the Rieske iron-sulfur protein to cytochrome c. Mutations in CYC1 cause nuclear-encoded mitochondrial complex III deficiency (MC3DN6), leading to multisystem disorders including lactic acidosis, hypotonia, and encephalopathy.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Mitochondrial complex III deficiency, nuclear type 6 (MC3DN6) | Loss-of-function mutations impair electron transfer, reducing ATP production and increasing reactive oxygen species. | ClinVar, OMIM |
| Leigh syndrome | Disruption of Complex III leads to energy failure in the brainstem and basal ganglia. | ClinVar, OMIM |
| Cardiomyopathy | Impaired mitochondrial respiration in cardiac muscle due to Complex III dysfunction. | ClinVar |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Heart | 28.5 | High |
| Skeletal muscle | 22.1 | High |
| Liver | 15.3 | Medium |
| Brain | 12.8 | Medium |
| Kidney | 11.4 | Medium |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK 293 | 32.0 | High expression in embryonic kidney cells |
| HeLa | 25.6 | High expression in cervical cancer cells |
| HepG2 | 18.9 | Medium expression in liver cancer cells |
| SH-SY5Y | 14.2 | Medium expression in neuroblastoma cells |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.289C>T (p.Arg97Trp) | Missense | Rare | Loss of heme binding, reduced Complex III activity |
| c.424G>A (p.Glu142Lys) | Missense | Rare | Impaired electron transfer, associated with MC3DN6 |
| c.1A>G (p.Met1Val) | Start loss | Rare | Complete loss of protein expression |
Mutation functional classification
Loss of Function (LOF)
Missense and start-loss mutations reduce or abolish cytochrome c1 activity, leading to Complex III deficiency.
Gain of Function (GOF)
No gain-of-function mutations reported.
Dominant Negative (DN)
No dominant-negative mutations reported; all pathogenic variants are recessive.
View complete mutation data：
Gene Ontology (GO)
| • mitochondrial electron transport (GO:0006122) | • mitochondrial respiratory chain complex III (GO:0005750) |
| • heme binding (GO:0020037) | • electron transfer activity (GO:0009055) |
| • mitochondrion (GO:0005739) |
Pathways
• Electron Transport Chain (Complex III) - KEGG: hsa00190
• Oxidative phosphorylation - Reactome: R-HSA-611105
• Respiratory electron transport - WikiPathways: WP111
Protein Summary
Cytochrome c1 (CYC1) is a 325-amino acid heme-containing protein localized to the inner mitochondrial membrane. It is an essential subunit of Complex III (ubiquinol-cytochrome c reductase), accepting electrons from the Rieske iron-sulfur protein and transferring them to cytochrome c. The protein contains a heme b-binding domain and a C-terminal transmembrane anchor. Pathogenic variants disrupt electron flow, causing mitochondrial complex III deficiency.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| CYC1 Knockout HEK293 Cell Line | EDJ-KQ4391 | Human | 1537 | Details Get a Quote |
| CYC1 Knockout A-549 Cell Line | EDJ-KQ26918 | Human | 1537 | Details Get a Quote |
| CYC1 Knockout HCT 116 Cell Line | EDJ-KQ26919 | Human | 1537 | Details Get a Quote |
| CYC1 Knockout HeLa Cell Line | EDJ-KQ26920 | Human | 1537 | Details Get a Quote |
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