HCCS: Holocytochrome c Synthase
Mitochondrial heme lyase essential for cytochrome c maturation and X-linked disease
Gene Information Card
| Symbol | HCCS |
|---|---|
| Full Name | Holocytochrome c synthase |
| Gene Type | Protein coding |
| Chromosomal Location | Xp22.2 |
| NCBI Gene ID | 3052 ncbi.nlm.nih.gov/gene/3052 |
| Ensembl ID | ENSG00000147133 |
| UniProt ID | P53701 |
| OMIM ID | 300056 |
| HGNC ID | 4837 |
| Aliases | CCHL, HCS, MLS, MCOPS7 |
Description
HCCS encodes holocytochrome c synthase, a mitochondrial enzyme that catalyzes the covalent attachment of heme to apocytochrome c and c1, essential for electron transport chain function. Mutations cause X-linked microphthalmia with linear skin defects syndrome (MLS).
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Microphthalmia, syndromic 7 (MCOPS7) | Loss of function leads to defective cytochrome c maturation, impaired mitochondrial respiration, and developmental defects | OMIM #309801 |
| Linear skin defects with multiple congenital anomalies 1 (LSDMCA1) | HCCS haploinsufficiency disrupts mitochondrial function in ectodermal tissues | OMIM #309801 |
| X-linked microphthalmia with linear skin defects (MLS) | Hypomorphic or null mutations cause variable microphthalmia, sclerocornea, and linear erythematous skin lesions | ClinVar, OMIM |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Heart | 28.5 | High |
| Skeletal muscle | 18.2 | Medium |
| Liver | 12.1 | Medium |
| Brain | 8.4 | Low |
| Kidney | 7.9 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 15.3 | Cervical cancer line |
| HEK293 | 12.7 | Embryonic kidney |
| K562 | 10.1 | Leukemia line |
| HepG2 | 9.8 | Hepatocellular carcinoma |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G (p.Met1?) | Missense/start loss | Rare | Loss of translation initiation |
| c.254_255delAG (p.Glu85Valfs*2) | Frameshift | Rare | Premature truncation, loss of function |
| c.427C>T (p.Arg143*) | Nonsense | Rare | Nonsense-mediated decay, loss of function |
| Whole gene deletion | Copy number loss | Rare | Haploinsufficiency, MLS phenotype |
Mutation functional classification
Loss of Function (LOF)
Most reported mutations (nonsense, frameshift, deletions) cause loss of heme lyase activity, leading to mitochondrial dysfunction and MLS.
Gain of Function (GOF)
Not described.
Dominant Negative (DN)
Not described; disease mechanism is haploinsufficiency.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Mitochondrial cytochrome c maturation (R-HSA-8964539)
• Electron transport chain (Complex III-IV)
Protein Summary
Holocytochrome c synthase (HCCS) is a 30.5 kDa mitochondrial inner membrane protein that attaches heme to apocytochrome c and c1 via thioether bonds. It is essential for functional cytochrome c and mitochondrial respiration. Deficiency leads to X-linked microphthalmia with linear skin defects (MLS).
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| HCCS Knockout HEK293 Cell Line | EDJ-KQ4855 | Human | 3052 | Details Get a Quote |
| HCCS Knockout A-549 Cell Line | EDJ-KQ27631 | Human | 3052 | Details Get a Quote |
| HCCS Knockout HCT 116 Cell Line | EDJ-KQ27632 | Human | 3052 | Details Get a Quote |
| HCCS Knockout HeLa Cell Line | EDJ-KQ27633 | Human | 3052 | Details Get a Quote |
Displaying Records 1 To 4 Of 4 Records
