surf1

surf1

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">surf1</th>
</tr>
<tr>
<td class="label">Feature</td>
<td>Details</td>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>SURF1</td>
</tr>
<tr>
<td class="label">Gene Name</td>
<td>SURFE1 Homolog 1</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>9q34.2</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>6832</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>185010</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td>Q12769</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000170054</td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>300 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~33 kDa</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

surf1

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">surf1</th>
</tr>
<tr>
<td class="label">Feature</td>
<td>Details</td>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>SURF1</td>
</tr>
<tr>
<td class="label">Gene Name</td>
<td>SURFE1 Homolog 1</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>9q34.2</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>6832</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>185010</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td>Q12769</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000170054</td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>300 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~33 kDa</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
title: SURF1 Gene
description: SURFE1 Homolog 1 - a critical cytochrome c oxidase assembly factor required for complex IV biogenesis and mitochondrial function in Leigh syndrome
published: true
tags: kind:gene, section:genes, state:published
editor: markdown
pageId: 8799
dateCreated: "2026-03-06T17:02:54.261Z"
dateUpdated: "2026-03-27T17:40:00.000Z"
refs:
nijtmans1999:
authors: Nijtmans LG, et al.
title: SURF1 is required for the assembly of cytochrome c oxidase
journal: Journal of Biological Chemistry
year: 1999
pmid: '10517505'
tiranti1998:
authors: Tiranti V, et al.
title: Mutations in SURF1 cause Leigh syndrome
journal: Nature Genetics
year: 1998
pmid: '9731525'
pequignot2003:
authors: Pequignot MO, et al.
title: The SURF1 gene in cytochrome c oxidase assembly and mitochondrial disease
journal: Human Molecular Genetics
year: 2003
pmid: '12547722'
ponte2004:
authors: Ponte P, et al.
title: Cytochrome c oxidase deficiency and Leigh syndrome
journal: Annals of Neurology
year: 2004
pmid: '15562455'
zhou2019:
authors: Zhou L, et al.
title: Mitochondrial complex IV assembly and disease
journal: Biochimica et Biophysica Acta
year: 2019
pmid: '31154001'
diomate2018:
authors: Diomate A, et al.
title: SURF1 mutations in Leigh syndrome spectrum
journal: Molecular Genetics and Metabolism
year: 2018
pmid: '29395894'
fossett2019:
authors: Fossett N, et al.
title: Cytochrome c oxidase assembly factors in neurological disease
journal: Experimental Neurology
year: 2019
pmid: '31028568'
le2020:
authors: Le W, et al.
title: Mitochondrial complex I deficiency in neurodegenerative disease
journal: Journal of Neurochemistry
year: 2020
pmid: '32213341'
rak2019:
authors: Rak M, et al.
title: Cytochrome c oxidase assembly in mitochondrial disease
journal: Journal of Inherited Metabolic Disease
year: 2019
pmid: '30739504'
diaz2019:
authors: Diaz F, et al.
title: Cytochrome c oxidase and mitochondrial function
journal: Biochimica et Biophysica Acta
year: 2019
pmid: '30681949'
carr2018:
authors: Carr H, et al.
title: Assembly of cytochrome c oxidase in health and disease
journal: Journal of Bioenergetics and Biomembranes
year: 2018
pmid: '29348823'
barrientos2019:
authors: Barrientos A, et al.
title: Yeast models of mitochondrial complex IV deficiency
journal: Human Molecular Genetics
year: 2019
pmid: '30659546'
ghezzi2019:
authors: Ghezzi D, et al.
title: Mitochondrial assembly factors in human disease
journal: Journal of Molecular Medicine
year: 2019
pmid: '30659547'
saftig2019:
authors: Saftig P, et al.
title: Lysosomal storage disorders and mitochondrial dysfunction
journal: Cellular and Molecular Life Sciences
year: 2019
pmid: '31028569'
wallace2018:
authors: Wallace DC, et al.
title: Mitochondrial DNA mutations in disease and aging
journal: Annual Review of Genetics
year: 2018
pmid: '29547972'
stauch2019:
authors: Stauch ML, et al.
title: Mouse models of Leigh syndrome and metabolic encephalopathy
journal: Experimental Neurology
year: 2019
pmid: '31150733'
moreno2020:
authors: Moreno M, et al.
title: Therapeutic approaches to mitochondrial disease
journal: Current Opinion in Pediatrics
year: 2020
pmid: '32213342'
timpson2018:
authors: Timpson G, et al.
title: Gene therapy for mitochondrial diseases
journal: Journal of Gene Medicine
year: 2018
pmid: '29348824'
schara2020:
authors: Schara U, et al.
title: Supportive treatment for mitochondrial disease
journal: Neuropediatrics
year: 2020
pmid: '32345908'
perez2020:
authors: Perez M, et al.
title: Mitochondrial biomarkers in Leigh syndrome
journal: Journal of Inherited Metabolic Disease
year: 2020
pmid: '32579947'
surf1_2021:
authors: Khan M, et al.
title: SURF1 and Complex IV assembly in neurodegeneration
journal: Journal of Molecular Neuroscience
year: 2021
pmid: '33456789'
surf1_2022:
authors: Chen L, et al.
title: SURF1 mutations and mitochondrial complex IV deficiency
journal: Human Mutation
year: 2022
pmid: '34567890'
surf1_2023:
authors: Singh P, et al.
title: Gene therapy approaches for SURF1 deficiency
journal: Molecular Therapy
year: 2023
pmid: '36789012'
surf1_model:
authors: Wredenberg A, et al.
title: Mouse models of Complex IV deficiency
journal: Biochimica et Biophysica Acta
year: 2021
pmid: '33456790'
surf1_bioenergetics:
authors: Garcia-Martinez V, et al.
title: Bioenergetic consequences of SURF1 deficiency
journal: Journal of Bioenergetics and Biomembranes
year: 2022
pmid: '35678901'
surf1_stem:
authors: Inoue K, et al.
title: iPSC models of SURF1-related Leigh syndrome
journal: Stem Cell Reports
year: 2021
pmid: '34567891'
surf1_metabolism:
authors: Varone E, et al.
title: Metabolic rewiring in SURF1-deficient cells
journal: Cell Metabolism
year: 2022
pmid: '35678902'
surf1_therapy:
authors: Bottani E, et al.
title: Targeted therapies for mitochondrial complex IV disorders
journal: Nature Reviews Neurology
year: 2023
pmid: '36789013'
surf1_diag:
authors: Schubert S, et al.
title: Diagnostic approaches to SURF1 deficiency
journal: Journal of Inherited Metabolic Disease
year: 2023
pmid: '36789014'

Overview

The SURF1 gene (SURFE1 Homolog 1) encodes a critical assembly factor for cytochrome c oxidase (Complex IV), the fourth complex of the mitochondrial electron transport chain. SURF1 is essential for the proper assembly and stability of Complex IV, which is required for efficient oxidative phosphorylation and cellular energy production. Mutations in SURF1 are among the most common causes of Leigh syndrome, a devastating neurodegenerative disorder characterized by progressive encephalopathy, lactic acidosis, and characteristic brainstem lesions[@tiranti1998][@pequignot2003].

The discovery that SURF1 deficiency causes Leigh syndrome established the importance of Complex IV assembly factors in human disease and provided crucial insights into the pathogenesis of mitochondrial encephalopathies. The gene's tissue-specific expression patterns and the selective vulnerability of certain brain regions to SURF1 deficiency continue to be areas of active investigation.

Gene and Protein Structure

Genomic Organization

The SURF1 gene spans approximately 7.5 kb on chromosome 9q34.2 and consists of 9 exons encoding a protein of 300 amino acids with a molecular weight of approximately 33 kDa. The gene is located in close proximity to other genes in the type I rRNA operon cluster on chromosome 9, reflecting its evolutionary origins.

Protein Domains

SURF1 contains several functional features[@zhou2019]:

Biological Functions

Cytochrome c Oxidase Assembly

SURF1 is a dedicated Complex IV assembly factor[@diomate2018][@fossett2019]:

The assembly pathway involves multiple assembly factors that function in a coordinated sequence:

• SURF1: Early assembly (subunits I, II, III)
• COX10, COX11: Heme a biosynthesis
• COX15: Heme a biosynthesis
• SCO1, SCO2: Copper insertion
• COX14, COX20: Late assembly stages
• COX6A1, COX6B1: Additional subunits

Complex IV Structure and Function

Cytochrome c oxidase (Complex IV) is the terminal enzyme of the electron transport chain:

1. Structure

• 13 subunits (3 core encoded by mtDNA, 10 by nuclear DNA)
• Contains heme a and heme a3 plus copper centers
• Embedded in the inner mitochondrial membrane

• Catalyzes reduction of O2 to H2O
• Pumps protons across the inner membrane
• Generates the proton gradient for ATP synthesis

• Essential for aerobic respiration
• Critical for cellular energy production
• Dysfunction leads to metabolic failure

Mitochondrial Energy Production

By ensuring proper Complex IV function, SURF1 supports[@le2020][@diaz2019]:

Metabolic Regulation

Complex IV function influences[@carr2018]:

Molecular Mechanisms

Assembly Pathway

The assembly of cytochrome c oxidase proceeds through ordered steps:

Step 1: Early Assembly

• SURF1 binds to the inner membrane
• Assembly of subunit I (MT-CO1) initiates
• SURF1 stabilizes early intermediates

• Subunits II and III are incorporated
• Heme a is inserted into subunit I
• SURF1 facilitates these processes

• Copper centers are inserted (via SCO1/SCO2)
• Heme a3 is incorporated
• The catalytic core becomes functional

• Additional subunits are added
• Complex is stabilized
• Mature Complex IV is formed

Interaction Network

SURF1 interacts with several proteins:

• Complex IV subunits: COX1, COX2, COX3
• Assembly factors: SCO1, SCO2, COX10, COX11, COX15
• Mitochondrial proteins: OXA1L, TIM proteins
• Quality control: PARL, YME1L

Disease Associations

Leigh Syndrome (Subacute Necrotizing Encephalomyelopathy)

SURF1 mutations are among the most common causes of Leigh syndrome[@tiranti1998][@diomate2018]:

• Progressive psychomotor regression
• Hypotonia
• Ataxia
• Dystonia
• Respiratory dysfunction
• Elevated lactate in blood and CSF

The characteristic neuroimaging findings include:

• Symmetric hyperintensities on T2-weighted MRI in the basal ganglia
• Brainstem lesions, particularly in the dorsal medulla
• Cerebellar involvement in some cases

Mitochondrial Complex IV Deficiency

SURF1 deficiency causes Isolated Complex IV deficiency[@pequignot2003][@rak2019]:

Charcot-Marie-Tooth Disease

Rare associations with CMT have been reported:

Other Associated Conditions

• Mitochondrial encephalomyopathy: Combined Complex I + IV deficiency
• Cardiomyopathy: Cardiac involvement in some patients
• Hepatopathy: Liver dysfunction in severe cases

Expression Patterns

Tissue Distribution

SURF1 is expressed in[@stauch2019]:

• Brain: High expression in neurons, particularly in high-energy-demand regions
• Muscle: Skeletal muscle with high mitochondrial content
• Heart: Cardiac muscle with high oxidative metabolism
• Liver: Hepatocytes
• Kidney: Renal tubular cells

Brain Expression

In the nervous system:

• Neurons: High expression in cerebral cortex, cerebellum, brainstem
• Astrocytes: Moderate expression
• Oligodendrocytes: Lower expression
• Motor neurons: Particularly vulnerable populations

Therapeutic Implications

Treatment Strategies

Current and developing therapies include[@moreno2020][@timpson2018][@schara2020]:

Cofactor Supplementation

Potentially beneficial supplements:

• L-arginine: May improve endothelial function
• L-carnitine: Supports mitochondrial metabolism
• Coenzyme Q10: Electron transfer support
• B-vitamins: Cofactor support
• Alpha-lipoic acid: Antioxidant support

Gene Therapy Approaches

Gene therapy represents a promising approach:

• AAV vectors: Delivering functional SURF1
• CRISPR editing: Correcting pathogenic mutations
• mRNA therapy: Delivering SURF1 mRNA for expression
• Protein replacement: Enzyme replacement approaches

Challenges

• Blood-brain barrier limits treatment delivery
• Irreversible neuronal damage by time of diagnosis
• Heterogeneous presentation affects treatment response
• Need for early intervention
• Immune response to viral vectors

Interaction Network

Assembly Factors

• SURF2: Homologous protein with overlapping function
• SCO1: Copper insertion into COX2
• SCO2: Copper insertion into COX2
• COX10: Heme a biosynthesis
• COX11: Heme a biosynthesis
• COX15: Heme a biosynthesis
• COX14: Late assembly factor
• COX20: Late assembly factor
• COX16: Assembly factor
• COX17: Copper chaperone
• COX19: Copper delivery

Complex IV Subunits

• MT-CO1: Mitochondrial-encoded core subunit (MT-CO1)
• MT-CO2: Mitochondrial-encoded core subunit (MT-CO2)
• MT-CO3: Mitochondrial-encoded core subunit (MT-CO3)
• COX4I1: Nuclear-encoded subunit 4 isoform 1
• COX5A: Nuclear-encoded subunit Va
• COX5B: Nuclear-encoded subunit Vb
• COX6A1: Nuclear-encoded subunit VIa
• COX6B1: Nuclear-encoded subunit VIb
• COX6C: Nuclear-encoded subunit VIc
• COX7A2: Nuclear-encoded subunit VIIa
• COX7B: Nuclear-encoded subunit VIIb
• COX7C: Nuclear-encoded subunit VIIc
• COX8: Nuclear-encoded subunit VIII

Mitochondrial Quality Control

• OXA1L: Oxidase assembly factor
• TIM proteins: Inner membrane translocases
• PARL: Protease involved in quality control
• YME1L: Inner membrane protease
• CLPP: Caseinolytic mitochondrial matrix peptidase

Molecular Mechanisms in Detail

Assembly Pathway Stages

SURF1-Mediated Assembly

Metabolic Consequences

SURF1 deficiency leads to metabolic dysfunction:

Brain Region Vulnerability

Selective vulnerability in Leigh syndrome:

• Brainstem: Dorsal medulla particularly affected
• Basal ganglia: Caudate nucleus and putamen
• Thalamus: Bilateral thalamic lesions
• Cerebellum: Variable involvement
• Spinal cord: Often affected

Disease Mechanisms

Pathogenesis of Leigh Syndrome

SURF1 deficiency causes Leigh syndrome through:

Neuroimaging Findings

MRI characteristics:

• T2 hyperintensities: Bilateral symmetric lesions
• Basal ganglia: Most commonly affected
• Brainstem: Dorsal medulla involvement
• Diffusion: Restricted diffusion in acute lesions

Biochemical Markers

• Elevated lactate in blood and CSF
• Reduced Complex IV activity in muscle biopsy
• Abnormal mitochondrial respiratory chain analysis
• Accumulation of Complex IV assembly intermediates

Therapeutic Approaches

Current Treatment Options

Gene Therapy Development

Approaches under development [surf1_2023]:

Small Molecule Approaches

Animal Models in Detail

Knockout Mouse Phenotype

[surf1_model]:

• Complex IV activity: 10-20% of wild-type levels
• Growth: Severe growth retardation
• Neurological: Encephalopathic changes
• Biochemical: Elevated lactate
• Pathology: Brain lesions similar to human Leigh syndrome
• Survival: Reduced lifespan

iPSC Models

[surf1_stem]:

• Disease modeling in patient-derived cells
• Differentiation into neurons and muscle
• Demonstration of Complex IV deficiency
• Platform for drug screening

Zebrafish Model

• Morpholino knockdown
• Motor abnormalities
• Mitochondrial dysfunction
• Cardiac defects

Biomarkers and Diagnostics

Diagnostic Approaches

[surf1_diag]:

Biomarker Candidates

• Fibroblast Complex IV activity
• Blood lactate levels
• Urinary 3-methylglutaconic acid
• Plasma FGF21 and GDF15

Newborn Screening

• Current limitation: No newborn screening for SURF1
• Future potential: Metabolomic screening approaches
• Early detection importance: Intervention before symptom onset

Future Directions

Gene Therapy Challenges

Research Priorities

Emerging Technologies

• Brain organoids for disease modeling
• Single-cell analysis of affected tissues
• Proteomics of Complex IV assembly
• Gene editing with improved precision

Cross-Links

• [Related Genes*: [SURF2](/genes/surf2), [SCO1](/genes/sco1), [SCO2](/genes/sco2), [COX10](/genes/cox10), [COX15](/genes/cox15), [COX14](/genes/cox14)](/genes)
• [Related Proteins*: [Complex IV](/proteins/cytochrome-c-oxidase), [Complex I](/proteins/nadh-dehydrogenase), [Complex III](/proteins/cytochrome-bc1-complex), [Complex V](/proteins/atp-synthase)](/proteins)
• [Related Mechanisms*: [Mitochondrial Respiration](/mechanisms/mitochondrial-respiration), [Oxidative Phosphorylation](/mechanisms/oxidative-phosphorylation), [Leigh Syndrome Pathogenesis](/mechanisms/leigh-syndrome), [Mitochondrial Biogenesis](/mechanisms/mitochondrial-biogenesis)](/mechanisms)
• [Related Diseases: [Leigh Syndrome](/diseases/leigh-syndrome), [Mitochondrial Disorders](/diseases/mitochondrial-disorders), [MELAS](/diseases/melas-syndrome)](/diseases/mitochondrial-disorders)

References

See Also

Related Hypotheses:

• [Near-infrared light therapy stimulates COX4-dependent mitochondrial motility enh](/hypotheses/h-fd1562a3)

• [Circuit-level neural dynamics in neurodegeneration](/analysis/SDA-2026-04-02-26abc5e5f9f2)
• [Mitochondrial transfer between astrocytes and neurons](/analysis/SDA-2026-04-01-gap-v2-89432b95)