COX6B1

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0045277 respiratory chain complex IV	IBA GO_REF:0000033	ACCEPT	Summary: COX6B1 is a bona fide subunit of respiratory chain Complex IV, supported by the intact human Complex IV structure and ComplexPortal annotation. The 3.3 Å cryo-EM structure (PDB 5Z62) of the 14-subunit human Complex IV places COX6B1 in the assembled holoenzyme. Reason: Core complex-membership annotation. Supporting Evidence: PMID:30030519 we obtained the entire CIV structure containing 14 subunits, which includes the extra subunit NDUFA4
GO:0005739 mitochondrion	IBA GO_REF:0000033	ACCEPT	Summary: COX6B1 is a mitochondrial protein as part of mitochondrial cytochrome c oxidase. Reason: Correct broad localization.
GO:0005743 mitochondrial inner membrane	IBA GO_REF:0000033	ACCEPT	Summary: COX6B1 associates with Complex IV at the mitochondrial inner membrane on the intermembrane-space side. Reason: Correct localization for a peripheral membrane subunit of Complex IV.
GO:0005739 mitochondrion	IEA GO_REF:0000002	ACCEPT	Summary: COX6B1 is a mitochondrial protein as part of mitochondrial cytochrome c oxidase. Reason: Correct broad localization.
GO:0005743 mitochondrial inner membrane	IEA GO_REF:0000120	ACCEPT	Summary: COX6B1 associates with Complex IV at the mitochondrial inner membrane on the intermembrane-space side. Reason: Correct localization for a peripheral membrane subunit of Complex IV.
GO:0045277 respiratory chain complex IV	IEA GO_REF:0000120	ACCEPT	Summary: COX6B1 is a bona fide subunit of respiratory chain Complex IV, supported by the intact human Complex IV structure and ComplexPortal annotation. The 3.3 Å cryo-EM structure (PDB 5Z62) of the 14-subunit human Complex IV places COX6B1 in the assembled holoenzyme. Reason: Core complex-membership annotation. Supporting Evidence: PMID:30030519 we obtained the entire CIV structure containing 14 subunits, which includes the extra subunit NDUFA4
GO:1902600 proton transmembrane transport	IEA GO_REF:0000108	MARK AS OVER ANNOTATED	Summary: Complex IV pumps protons, but COX6B1 is not itself the proton-translocation path or catalytic core. The automated inference projects a whole-complex process onto a peripheral subunit. Reason: Over-annotated at the individual gene-product level. The appropriate core statement is Complex IV membership and contribution to the complex-level activity. Falcon deep research confirms COX6B1 is a small accessory subunit, not a catalytic/proton-translocation component, and that its loss does not change proton stoichiometry (only enzyme activity and cooperativity). Supporting Evidence: file:human/COX6B1/COX6B1-deep-research-falcon.md Experimental removal/loss of COX6B1 (e.g., during mild solubilization) leads to monomerization of COX and is associated with a ~two-fold increase in enzyme activity without changing proton stoichiometry, interpreted as loss of inter-monomer cooperativity and altered cytochrome c binding kinetics.
GO:0006119 oxidative phosphorylation	IEA GO_REF:0000041	KEEP AS NON CORE	Summary: COX6B1 participates in oxidative phosphorylation through Complex IV, but the term is broader than the gene product's specific role. The 3.3 Å cryo-EM structure (PDB 5Z62) of the 14-subunit human Complex IV places COX6B1 within the assembled terminal oxidase of the electron transport chain. Reason: Keep as a broad pathway-level annotation, not the core function statement. Supporting Evidence: PMID:30030519 CIV is the terminal oxidase of the electron transport chain in mitochondria. file:human/COX6B1/COX6B1-deep-research-falcon.md COX6B1 functions within the oxidative phosphorylation pathway as a complex IV accessory subunit that contributes to quaternary structure (dimerization) and is linked to assembly/biogenesis of the complex.
GO:0006123 mitochondrial electron transport, cytochrome c to oxygen	NAS PMID:30030519 Structure of the intact 14-subunit human cytochrome c oxidas...	ACCEPT	Summary: COX6B1 participates in cytochrome-c-to-oxygen electron transport as part of the intact Complex IV holoenzyme. Reason: Correct complex-level process annotation for a structural Complex IV subunit. Supporting Evidence: PMID:30030519 CIV is the terminal oxidase of the electron transport chain in mitochondria. file:human/COX6B1/COX6B1-deep-research-falcon.md Cytochrome c oxidase (complex IV; COX/CCO) is the terminal enzyme of the mitochondrial electron transport chain. Its catalytic core transfers electrons from cytochrome c to molecular oxygen and contributes to the proton gradient used for ATP synthesis.
GO:0031966 mitochondrial membrane	IDA PMID:30030519 Structure of the intact 14-subunit human cytochrome c oxidas...	ACCEPT	Summary: Mitochondrial membrane is a correct broader localization for a peripheral inner-membrane Complex IV subunit. Reason: Accept as correct but less specific than mitochondrial inner membrane. Supporting Evidence: PMID:30030519 Current opinions point out that CIV exists in two states under physiological conditions, either being assembled into supercomplexes or freely scattered on mitochondrial inner membrane.
GO:0045277 respiratory chain complex IV	IPI PMID:30030519 Structure of the intact 14-subunit human cytochrome c oxidas...	ACCEPT	Summary: COX6B1 is a bona fide subunit of respiratory chain Complex IV, supported by the intact human Complex IV structure and ComplexPortal annotation. Reason: Core complex-membership annotation. Supporting Evidence: PMID:30030519 we obtained the entire CIV structure containing 14 subunits, which includes the extra subunit NDUFA4 file:human/COX6B1/COX6B1-deep-research-falcon.md COX6B1 is not catalytic; it is a small, nuclear-encoded accessory subunit that modulates structure/assembly and function of the complex.
GO:0045333 cellular respiration	NAS PMID:30030519 Structure of the intact 14-subunit human cytochrome c oxidas...	KEEP AS NON CORE	Summary: Cellular respiration is correct at the pathway level but too broad for the specific COX6B1 role. Reason: Keep as non-core.
GO:0005739 mitochondrion	IDA GO_REF:0000052	ACCEPT	Summary: COX6B1 is a mitochondrial protein as part of mitochondrial cytochrome c oxidase. Reason: Correct broad localization.
GO:0005743 mitochondrial inner membrane	EXP PMID:30030519 Structure of the intact 14-subunit human cytochrome c oxidas...	ACCEPT	Summary: COX6B1 associates with Complex IV at the mitochondrial inner membrane on the intermembrane-space side. Reason: Correct localization for a peripheral membrane subunit of Complex IV. Supporting Evidence: PMID:30030519 Current opinions point out that CIV exists in two states under physiological conditions, either being assembled into supercomplexes or freely scattered on mitochondrial inner membrane. file:human/COX6B1/COX6B1-deep-research-falcon.md COX6B1 is positioned on the intermembrane-space (IMS)-facing side of complex IV. Structural placement from reviews and figure evidence shows COX6B1 exposed on the IMS side and situated at/near the dimer interface.
GO:0005739 mitochondrion	HTP PMID:34800366 Quantitative high-confidence human mitochondrial proteome an...	ACCEPT	Summary: COX6B1 is a mitochondrial protein as part of mitochondrial cytochrome c oxidase. Reason: Correct broad localization. Supporting Evidence: file:human/COX6B1/COX6B1-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion
GO:0021762 substantia nigra development	HEP PMID:22926577 Quantitative proteomic analysis of human substantia nigra in...	KEEP AS NON CORE	Summary: The substantia nigra development annotation comes from phenotype/proteomic evidence and does not describe the core molecular role of COX6B1. Reason: Keep as non-core/phenotype-associated rather than a primary gene function.
GO:0005743 mitochondrial inner membrane	TAS Reactome:R-HSA-163214	ACCEPT	Summary: COX6B1 associates with Complex IV at the mitochondrial inner membrane on the intermembrane-space side. Reason: Correct localization for a peripheral membrane subunit of Complex IV.
GO:0005743 mitochondrial inner membrane	TAS Reactome:R-HSA-9709406	ACCEPT	Summary: COX6B1 associates with Complex IV at the mitochondrial inner membrane on the intermembrane-space side. Reason: Correct localization for a peripheral membrane subunit of Complex IV.
GO:0005743 mitochondrial inner membrane	TAS Reactome:R-HSA-9865663	ACCEPT	Summary: COX6B1 associates with Complex IV at the mitochondrial inner membrane on the intermembrane-space side. Reason: Correct localization for a peripheral membrane subunit of Complex IV.
GO:0004129 cytochrome-c oxidase activity	NAS PMID:2172092 Isolation of cDNAs encoding subunit VIb of cytochrome c oxid...	MARK AS OVER ANNOTATED	Summary: Cytochrome-c oxidase activity is the activity of the assembled Complex IV enzyme. COX6B1 contributes to this activity as a subunit but does not independently catalyze electron transfer or oxygen reduction. Reason: Classic example of whole-complex activity being over-attributed to a non-catalytic subunit. Represent this as contributes_to in the synthesized core function, not as independently enabled activity. Falcon deep research corroborates that COX6B1 is "not catalytic" and is instead a nuclear-encoded accessory subunit that modulates complex structure/assembly and function. Supporting Evidence: file:human/COX6B1/COX6B1-deep-research-falcon.md COX6B1 is not catalytic; it is a small, nuclear-encoded accessory subunit that modulates structure/assembly and function of the complex.

Core Functions

COX6B1 is a peripheral intermembrane-side structural/accessory subunit of mitochondrial Complex IV that bridges the two monomers at the dimer interface and supports cooperative cytochrome c binding kinetics. It contributes to the complex-level cytochrome-c oxidase activity and electron-transport process by supporting the assembled holoenzyme, and is also required for an early redox-sensitive step in Complex IV biogenesis (MT-CO2 maturation/metalation). Cytochrome-c oxidase catalytic activity should not be attributed to COX6B1 alone.

Directly Involved In:

mitochondrial electron transport, cytochrome c to oxygen

Cellular Locations:

mitochondrial inner membrane

In Complex:

respiratory chain complex IV

Supporting Evidence:

PMID:30030519
we obtained the entire CIV structure containing 14 subunits, which includes the extra subunit NDUFA4
file:human/COX6B1/COX6B1-uniprot.txt
Component of the cytochrome c oxidase (complex IV, CIV), a multisubunit enzyme composed of 14 subunits. SUBCELLULAR LOCATION: Mitochondrion inner membrane; Peripheral membrane protein; Intermembrane side.
file:human/COX6B1/COX6B1-deep-research-falcon.md
A consistent model is that COX6B1 **bridges the two monomers** in the COX dimer and supports dimer stability and cooperative function.
file:human/COX6B1/COX6B1-deep-research-falcon.md
COX6B1 is **not catalytic**; it is a **small, nuclear-encoded accessory subunit** that modulates structure/assembly and function of the complex.

References

GO_REF:0000002

Gene Ontology annotation through association of InterPro records with GO terms

InterPro2GO mapping (COX6B family domains) propagates mitochondrial and Complex IV-related annotations to COX6B1.

GO_REF:0000033

Annotation inferences using phylogenetic trees

PAINT/IBA phylogenetic propagation supports Complex IV membership, mitochondrial inner-membrane localization, and cytochrome-c-to-O2 electron transport for COX6B1 across COX6B orthologs.

GO_REF:0000041

Gene Ontology annotation based on UniPathway vocabulary mapping

UniPathway UPA00705 (oxidative phosphorylation) propagates participation in the OXPHOS pathway to COX6B1.

GO_REF:0000052

Gene Ontology annotation based on curation of immunofluorescence data

Curated immunofluorescence data (Human Protein Atlas) place COX6B1 in mitochondria.

GO_REF:0000108

Automatic assignment of GO terms using logical inference, based on on inter-ontology links

Logical inference from cytochrome-c oxidase activity (GO:0004129) propagates proton transmembrane transport (GO:1902600) to Complex IV subunits including COX6B1.

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

Combined automated IEA methods propagate inner mitochondrial membrane localization and Complex IV membership to COX6B1.

PMID:2172092

Isolation of cDNAs encoding subunit VIb of cytochrome c oxidase and steady-state levels of coxVIb mRNA in different tissues.

Cloned cDNAs encoding human cytochrome c oxidase subunit VIb (COX6B1) and characterized tissue-specific steady-state mRNA levels, identifying COX6B1 as a subunit of cytochrome c oxidase.

"Isolation of cDNAs encoding subunit VIb of cytochrome c oxidase and steady-state levels of coxVIb mRNA in different tissues."

PMID:22926577

Quantitative proteomic analysis of human substantia nigra in Alzheimer's disease, Huntington's disease and Multiple sclerosis.

Quantitative proteomics of human substantia nigra in neurodegenerative disease detected COX6B1, used to underpin a substantia-nigra-development phenotype association (HEP evidence).

"Quantitative proteomic analysis of human substantia nigra in Alzheimer's disease, Huntington's disease and Multiple sclerosis."

PMID:30030519

Structure of the intact 14-subunit human cytochrome c oxidase.

Cryo-EM structure (3.3 Å, PDB 5Z62) of human Complex IV confirms COX6B1 as a subunit of the intact 14-subunit holoenzyme on the intermembrane-space side and resolves its position at the dimer interface.

"we obtained the entire CIV structure containing 14 subunits, which includes the extra subunit NDUFA4"

PMID:34800366

Quantitative high-confidence human mitochondrial proteome and its dynamics in cellular context.

High-confidence mitochondrial proteome identifies COX6B1 as a mitochondrial protein.

"Quantitative high-confidence human mitochondrial proteome and its dynamics in cellular context."

Reactome:R-HSA-163214

Electron transfer from reduced cytochrome c to molecular oxygen

Reactome pathway describing Complex IV electron transfer from reduced cytochrome c to O2 places COX6B1 in the inner mitochondrial membrane as a CIV subunit.

"Electron transfer from reduced cytochrome c to molecular oxygen"

Reactome:R-HSA-9709406

CO binds to Cytochrome c oxidase

Reactome pathway describing carbon monoxide binding to CIV places COX6B1 in the inner mitochondrial membrane as part of the target enzyme.

"CO binds to Cytochrome c oxidase"

Reactome:R-HSA-9865663

MT-CO3, COX6A,B,7A and NDUFA4 bind to holo-MT-CO1,2 complex

Reactome CIV assembly step in which COX6A, COX6B (including COX6B1), COX7A and NDUFA4 join the holo-MT-CO1,2 complex; places COX6B1 in the inner mitochondrial membrane during late CIV assembly.

"MT-CO3, COX6A,B,7A and NDUFA4 bind to holo-MT-CO1,2 complex"

file:human/COX6B1/COX6B1-deep-research-falcon.md

Falcon deep research for human COX6B1

COX6B1 is a small, nuclear-encoded accessory subunit of mitochondrial Complex IV and is not a catalytic component; it modulates structure, assembly, and function of the complex.

"COX6B1 is **not catalytic**; it is a **small, nuclear-encoded accessory subunit** that modulates structure/assembly and function of the complex. "
COX6B1 is positioned on the intermembrane-space (IMS)-facing side of Complex IV at the dimer interface.

"COX6B1 is positioned on the **intermembrane-space (IMS)-facing side** of complex IV. Structural placement from reviews and figure evidence shows COX6B1 exposed on the IMS side and situated at/near the **dimer interface**. "
COX6B1 bridges the two monomers of the COX dimer and supports dimer stability and cooperative function; loss leads to monomerization and ~2-fold increase in enzyme activity without changing proton stoichiometry.

"Experimental removal/loss of COX6B1 (e.g., during mild solubilization) leads to **monomerization** of COX and is associated with a **~two-fold increase in enzyme activity** without changing proton stoichiometry, interpreted as loss of inter-monomer cooperativity and altered cytochrome c binding kinetics. "
Cytochrome c oxidase is the terminal enzyme of the mitochondrial electron transport chain, transferring electrons from cytochrome c to molecular oxygen and contributing to the proton gradient used for ATP synthesis.

"Cytochrome c oxidase (complex IV; COX/CCO) is the terminal enzyme of the mitochondrial electron transport chain. Its catalytic core transfers electrons from cytochrome c to molecular oxygen and contributes to the proton gradient used for ATP synthesis. "
COX6B1 functions within the oxidative phosphorylation pathway as a Complex IV accessory subunit contributing to quaternary structure (dimerization) and assembly/biogenesis.

"COX6B1 functions within the **oxidative phosphorylation** pathway as a complex IV accessory subunit that contributes to **quaternary structure** (dimerization) and is linked to **assembly/biogenesis** of the complex. "
Recent KO/complementation evidence indicates COX6B1 is essential for an early, redox-sensitive step in Complex IV biogenesis, particularly affecting MT-CO2 maturation/metalation with altered copper-delivery/assembly factors (COA6, SCO1, SCO2).

"More recent mechanistic work (preprint) using COX6B1 knockout/complementation in human cells argues COX6B1 is also essential for an **early, redox-sensitive step** in biogenesis—particularly affecting **MT-CO2 maturation/metalation**, with altered abundance/association of copper-delivery/assembly factors (e.g., COA6/SCO1/SCO2). "
Pathogenic homozygous missense variants in a conserved N-terminal arginine (R19/R20) cause infantile/early-onset encephalomyopathy with isolated Complex IV deficiency; severe cases include hydrocephalus and hypertrophic cardiomyopathy.

"Pathogenic **homozygous missense** variants in a conserved arginine in the N-terminus region are repeatedly highlighted. Depending on numbering conventions these appear as **R19H/R19C** or **R20H/R20C**. Reported phenotypes include **infantile/early-onset encephalomyopathy** with isolated complex IV deficiency; more severe presentations include **hydrocephalus** and **hypertrophic cardiomyopathy** (notably with Arg→Cys). "
Patient fibroblasts and muscle with Arg20His show reduced COX6B1 steady-state levels, decreased incorporation into assembling Complex IV, and accumulation of assembly intermediate S3; wild-type COX6B1 complementation restores Complex IV content and activity.

"A 2020 review summarizes evidence that patient fibroblasts and muscle with **Arg20His** show reduced COX6B1 steady-state levels and decreased incorporation into assembling complex IV, with accumulation of assembly intermediate **S3** and selective reduction in complex IV activity (other OXPHOS complexes relatively unaffected). Importantly, **wild-type COX6B1 complementation restores** complex IV content and activity, supporting causality. "
The somatic COX6B1 isoform is distinct from the testis-enriched paralog COX6B2; identity and isoform context are important for interpreting reproductive/cancer studies.

"COX VIb exists as (at least) a broadly expressed somatic isoform (**COX6B1**) and a testis-enriched isoform (**COX6B2**). This matters for interpretation of studies in reproductive tissues and cancers where COX6B2 may be induced. "

Suggested Experiments

Experiment: Cryo-EM of human Complex IV reconstituted with R19H/R20H/R20C COX6B1 variants alongside an in vitro CIV assembly assay using CRISPR COX6B1-KO HEK293 mitochondria complemented with WT vs. variant COX6B1. Quantify CIV holoenzyme levels by BN-PAGE, assembly-intermediate occupancy (S1/S2/S3), MT-CO2 metalation status (Cu content + SCO1/SCO2 co-IP), and respirometry.

Hypothesis: R19/R20 variants act primarily by blocking incorporation of COX6B1 into the S3 assembly intermediate and impair MT-CO2 copper delivery, rather than by destabilizing the assembled dimer interface.

Type: structural biology / mitochondrial biochemistry

Experiment: Native single-particle cytochrome c kinetic analyses of isolated dimeric versus monomeric COX from WT and COX6B1-KO human cells, pairing this with high-resolution respirometry under physiological cytochrome c concentrations and at varying ATP/ADP ratios.

Hypothesis: The 2-fold activity gain of monomeric CIV in vitro reflects loss of negative cooperativity that is essential in vivo for matching CIV turnover to upstream electron supply; under physiological cytochrome c and energy-charge constraints, monomeric CIV under-performs.

Type: enzyme kinetics / respirometry

Experiment: Patient-derived iPSC differentiation to cardiomyocytes and cortical/spinal neurons from R19H/R20C COX6B1 patients vs. isogenic CRISPR-corrected controls. Assess CIV assembly (BN-PAGE), MT-CO2 maturation, supercomplex content, respirometry, ROS, and Ca2+ handling; pair with proteomic interactome mapping of COA6/SCO1/SCO2 around COX6B1.

Hypothesis: Patient cardiomyocytes show selective Complex IV assembly failure and MT-CO2 hypo-metalation that is rescued by wild-type COX6B1, with a steeper bioenergetic penalty than fibroblasts owing to higher CIV turnover demand.

Type: stem-cell biology / clinical model

Deep Research

Falcon

(COX6B1-deep-research-falcon.md)

this with annotations you find in gene/protein databases, but these can be outdated or inaccurate. Falcon Edison Scientific Literature 25 citations 2 artifacts 2026-05-30T03:51:44.166868

Edison artifact artifact-00 (text/markdown)

## Context ID: pqac-00000009 The requested information about the location and role of COX6B1 (subunit VIb1) is illustrated in Figures 2 and 3 of the document. F (image/png)

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Research report: Human COX6B1 (UniProt P14854) — functional annotation and recent literature

0. Target verification (mandatory)

The literature assembled here consistently matches the UniProt target P14854: COX6B1, the nuclear-encoded cytochrome c oxidase subunit VIb isoform 1 (COX VIb-1) in Homo sapiens, an accessory subunit of mitochondrial complex IV (cytochrome c oxidase, COX). Reviews distinguish it from the paralog COX6B2 (testis-enriched; sometimes expressed in cancers), confirming the correct gene/protein identity and organism context. (gladyck2021regulationofcox pages 12-13, cunatova2020roleofcytochrome pages 7-8, sinkler2017tissueandconditionspecific pages 8-9)

1. Key concepts, definitions, and current understanding

1.1 Cytochrome c oxidase (complex IV) and what COX6B1 is (and is not)

Cytochrome c oxidase (complex IV; COX/CCO) is the terminal enzyme of the mitochondrial electron transport chain. Its catalytic core transfers electrons from cytochrome c to molecular oxygen and contributes to the proton gradient used for ATP synthesis. COX6B1 is not catalytic; it is a small, nuclear-encoded accessory subunit that modulates structure/assembly and function of the complex. (sinkler2017tissueandconditionspecific pages 1-2, gladyck2021regulationofcox pages 12-13)

1.2 Subcellular localization and topology

COX6B1 is positioned on the intermembrane-space (IMS)-facing side of complex IV. Structural placement from reviews and figure evidence shows COX6B1 exposed on the IMS side and situated at/near the dimer interface. (cunatova2020roleofcytochrome pages 7-8, gladyck2021regulationofcox pages 12-13, cunatova2020roleofcytochrome media a8606d54)

1.3 COX dimerization, cooperativity, and cytochrome c interaction kinetics

A consistent model is that COX6B1 bridges the two monomers in the COX dimer and supports dimer stability and cooperative function. Experimental removal/loss of COX6B1 (e.g., during mild solubilization) leads to monomerization of COX and is associated with a ~two-fold increase in enzyme activity without changing proton stoichiometry, interpreted as loss of inter-monomer cooperativity and altered cytochrome c binding kinetics. (cunatova2020roleofcytochrome pages 7-8, sinkler2017tissueandconditionspecific pages 8-9)

1.4 Isoforms and paralogs

COX VIb exists as (at least) a broadly expressed somatic isoform (COX6B1) and a testis-enriched isoform (COX6B2). This matters for interpretation of studies in reproductive tissues and cancers where COX6B2 may be induced. (cunatova2020roleofcytochrome pages 7-8, sinkler2017tissueandconditionspecific pages 8-9)

2. Recent developments and latest research (prioritizing 2023–2024)

2.1 2024: COX6B1 as part of OXPHOS-based prognostic models (uveal melanoma)

A 2024 study built an oxidative phosphorylation (OXPHOS)-gene prognostic risk score model for uveal melanoma using 80 TCGA-UVM samples and external validation sets. COX6B1 was one of 9 OXPHOS-related genes in the final model. Reported performance included AUC > 0.88 for predicting 1–5 year survival, and an external-dataset median risk-score cutoff of 16.213 for stratifying high- vs low-risk groups. This is a real-world example of COX6B1 being operationalized as a feature in transcriptomic prognostic modeling (though not validated as a standalone biomarker in this paper). (zhan2024constructionofoxidative pages 1-2, zhan2024constructionofoxidative pages 2-4)

2.2 2024: Isoform context from mouse genetics (COX6B2) and implications for interpreting COX6B1

A 2024 CRISPR study knocked out Cox6b2 (testis-enriched paralog) in mice. The abstract reports male subfertility with low sperm motility, while sperm mitochondrial respiration appeared normal by oxygen consumption rate. This reinforces that VIb biology is isoform-dependent and that COX6B1 (somatic) may compensate in testis contexts. The paper reports CRISPR production statistics (e.g., electroporated eggs and mutant pups), highlighting feasibility of isoform-specific functional dissection in vivo. (shimada2024disruptionoftestisenriched pages 1-2)

2.3 2023: Conceptual linkage of Cox6b1 to supercomplex biology during dietary restriction

A 2023 review on dietary energy restriction discussed respiratory-chain supercomplex (SC) formation and notes Cox6b1 as involved in respiratory function and potentially complex IV regulation, in the context of dietary restriction–associated SC formation in mouse liver mitochondria. This source is conceptually relevant but does not provide COX6B1-specific quantitative measurements. (shimokawa2023mechanismsunderlyingretardation pages 5-8)

2.4 Important caveat about “latest mechanistic” COX6B1 literature

Within the retrieved corpus, most COX6B1-specific mechanistic and disease-variant work is concentrated in authoritative reviews (2017–2021) plus a newer mechanistic preprint (2025) rather than 2023–2024 primary mechanistic papers. This does not imply the field is inactive; it reflects the accessible set in this tool-assisted retrieval. (cunatova2025cox6b1securesa pages 6-8, cunatova2020roleofcytochrome pages 7-8, sinkler2017tissueandconditionspecific pages 8-9)

3. Primary function, biological processes, and pathways

3.1 Pathway context: oxidative phosphorylation and complex IV biogenesis

COX6B1 functions within the oxidative phosphorylation pathway as a complex IV accessory subunit that contributes to quaternary structure (dimerization) and is linked to assembly/biogenesis of the complex. Complex IV is embedded in the inner mitochondrial membrane, with domains projecting into IMS and matrix; COX6B1 is among the small nuclear-encoded subunits imported into mitochondria. (weraarpachai2012identificationandcharacterization pages 41-45, cunatova2020roleofcytochrome pages 7-8)

3.2 Assembly biology: late incorporation model vs essential early checkpoint

Earlier patient-cell–based interpretations suggested COX6B1 is added late in assembly (consistent with mutant COX6B1 showing reduced incorporation and accumulation of an assembly intermediate designated S3). (cunatova2020roleofcytochrome pages 10-11)

More recent mechanistic work (preprint) using COX6B1 knockout/complementation in human cells argues COX6B1 is also essential for an early, redox-sensitive step in biogenesis—particularly affecting MT-CO2 maturation/metalation, with altered abundance/association of copper-delivery/assembly factors (e.g., COA6/SCO1/SCO2). The authors report that an AOX-based redox rescue permits partial accumulation of assembly intermediates, but the rescued CIV subassembly has ~5% of wild-type CIV activity. (cunatova2025cox6b1securesa pages 6-8)

These two views can be reconciled as COX6B1 being: (i) structurally important at the mature/dimer stage and (ii) functionally required to stabilize or enable specific early assembly transitions that become especially evident under knockout perturbations. (cunatova2020roleofcytochrome pages 10-11, cunatova2025cox6b1securesa pages 6-8)

3.3 Structural placement and interfaces (expert synthesis)

Structural/functional reviews place COX6B1 atop the dimer on the IMS side, bridging monomers and contacting core subunits (notably II/III) in ways that can affect cytochrome c docking kinetics and/or local assembly of COX2-related modules. (gladyck2021regulationofcox pages 12-13, cunatova2020roleofcytochrome pages 7-8)

4. Disease relevance (clinical genetics and mechanisms)

4.1 Pathogenic variants and clinical phenotypes

Pathogenic homozygous missense variants in a conserved arginine in the N-terminus region are repeatedly highlighted. Depending on numbering conventions these appear as R19H/R19C or R20H/R20C. Reported phenotypes include infantile/early-onset encephalomyopathy with isolated complex IV deficiency; more severe presentations include hydrocephalus and hypertrophic cardiomyopathy (notably with Arg→Cys). (sinkler2017tissueandconditionspecific pages 8-9, cunatova2020roleofcytochrome pages 10-11, sinkler2017tissueandconditionspecific pages 3-5)

4.2 Molecular mechanism in patient-derived material

A 2020 review summarizes evidence that patient fibroblasts and muscle with Arg20His show reduced COX6B1 steady-state levels and decreased incorporation into assembling complex IV, with accumulation of assembly intermediate S3 and selective reduction in complex IV activity (other OXPHOS complexes relatively unaffected). Importantly, wild-type COX6B1 complementation restores complex IV content and activity, supporting causality. (cunatova2020roleofcytochrome pages 10-11)

5. Current applications and real-world implementations

5.1 Clinical testing / diagnostics

COX6B1 is clinically relevant as a bona fide nuclear gene for isolated complex IV deficiency. Practical implementation is typically through genomic testing (e.g., exome/genome sequencing panels for mitochondrial disease) followed by functional validation (complex IV activity assays, BN-PAGE assembly profiling, and complementation in patient cells as summarized). (cunatova2020roleofcytochrome pages 10-11, sinkler2017tissueandconditionspecific pages 3-5)

5.2 Cancer and systems-biology applications

COX6B1 is frequently used as an OXPHOS/mitochondrial respiration gene in transcriptomic signatures. In uveal melanoma, it contributed to a multigene OXPHOS risk model with strong ROC performance (AUC > 0.88 for 1–5 year survival prediction). These applications are real-world in the sense of computational prognostics, but remain translational until prospectively validated and clinically deployed. (zhan2024constructionofoxidative pages 1-2)

5.3 Model systems for functional dissection

Functional studies referenced in the assembled evidence include: (i) patient-cell rescue by wild-type COX6B1, (ii) KO/complementation approaches in human cell lines for assembly dissection, and (iii) paralog-specific KO mice (Cox6b2) for isoform physiology. (cunatova2020roleofcytochrome pages 10-11, cunatova2025cox6b1securesa pages 6-8, shimada2024disruptionoftestisenriched pages 1-2)

6. Relevant statistics and quantitative findings (from the retrieved sources)

~Two-fold activity increase of complex IV upon COX6B1/VIb loss/removal during solubilization, with no change in proton translocation stoichiometry (supports a regulatory/cooperative role). (cunatova2020roleofcytochrome pages 7-8)
In a COX6B1 KO context with AOX-based redox rescue, a complex IV subassembly (“IVsub”) retains ~5% of wild-type CIV activity (quantifies severity of functional deficit despite partial assembly). (cunatova2025cox6b1securesa pages 6-8)
Uveal melanoma prognostic model (2024) incorporating COX6B1 reports AUC > 0.88 for predicting 1–5 year survival; external dataset median cutoff 16.213 for risk stratification. (zhan2024constructionofoxidative pages 1-2, zhan2024constructionofoxidative pages 2-4)
Mouse Cox6b2 KO production statistics (2024) illustrate feasibility of isoform KO generation: for Cox6b2, 100 electroporated eggs, 94 transplanted, 21 mice born, 4 with Cox6b2 mutations (and analogous reported numbers for Cox8c). (shimada2024disruptionoftestisenriched pages 1-2)

7. Visual evidence (figures/tables)

Two key schematics from a 2020 review provide visual support:
- A figure showing COX6B1 labeled on the IMS side of complex IV among nuclear-encoded subunits (supports localization/topology). (cunatova2020roleofcytochrome media a8606d54)
- A figure summarizing alternative assembly models where COX6B appears either as a late-added component (sequential model) or preassembled within a module (modular model), relevant to reconciling late-incorporation views with newer early-checkpoint findings. (cunatova2020roleofcytochrome media 5dad9122)

8. Evidence map (summary table)

The following table consolidates core annotation claims and their supporting evidence.

Annotation area	Key claim	Supporting evidence (brief)	Citation IDs
Identity / isoforms	COX6B1 (UniProt P14854) is the human, nuclear-encoded somatic/ubiquitous cytochrome c oxidase subunit VIb1; it is distinct from the testis-enriched paralog COX6B2.	Reviews identify COX6B1 as COX VIb1/Cox12p, broadly expressed across tissues, while COX6B2 is testes-specific; COX6B1 is the relevant human somatic isoform for complex IV.	(gladyck2021regulationofcox pages 12-13, cunatova2020roleofcytochrome pages 7-8, sinkler2017tissueandconditionspecific pages 8-9)
Subcellular localization / topology	COX6B1 is an intermembrane-space-facing subunit of mitochondrial complex IV, positioned on the outer/IMS side of the holoenzyme.	Structural and review sources place VIb1 on the IMS side of cytochrome c oxidase, where it is exposed at the dimer interface; figure evidence also shows COX6B1 on the IMS side.	(gladyck2021regulationofcox pages 12-13, cunatova2020roleofcytochrome pages 7-8, cunatova2020roleofcytochrome media a8606d54)
Primary molecular function within complex IV	COX6B1 is an accessory structural/regulatory subunit of complex IV rather than a catalytic center; it supports cytochrome c oxidase function and is positioned near the cytochrome c interaction region.	COX catalyzes electron transfer from cytochrome c to O2 in the core subunits, while COX6B1 is a small nuclear-encoded subunit modeled near the cytochrome c binding site and required for proper complex IV activity.	(gladyck2021regulationofcox pages 12-13, sinkler2017tissueandconditionspecific pages 1-2)
Role in dimerization / cooperativity	COX6B1 helps bridge the two complex IV monomers, stabilizing the dimer and modulating inter-monomer cooperativity; removal/absence can monomerize COX and increase activity about twofold.	Reviews report that VIb connects monomers on the IMS side; mild solubilization causing COX6B1 loss leads to monomerization and ~2-fold higher activity without changing proton stoichiometry, consistent with altered cytochrome c binding cooperativity.	(cunatova2020roleofcytochrome pages 7-8, sinkler2017tissueandconditionspecific pages 8-9)
Role in assembly (early vs late)	Earlier models placed COX6B1 as a late-added subunit, but recent mechanistic work indicates it is also essential for an early redox-sensitive assembly step involving MT-CO2 maturation/metalation.	Patient-cell and review data linked mutant COX6B1 to reduced incorporation and accumulation of late intermediate S3; newer KO/complementation data show total loss of complex IV, block at MT-CO2 maturation, altered COA6/SCO factors, and support an indispensable early assembly role.	(cunatova2020roleofcytochrome pages 10-11, cunatova2025cox6b1securesa pages 6-8, cunatova2025cox6b1securesa pages 1-3, cunatova2020roleofcytochrome media 5dad9122)
Disease-causing variants / phenotypes	Pathogenic homozygous missense variants in conserved Arg20/Arg19 region (reported as R20H/R20C or R19H/R19C depending on numbering) cause isolated complex IV deficiency with severe infantile mitochondrial disease.	Reported phenotypes include infantile encephalomyopathy; hydrocephalus and hypertrophic cardiomyopathy with the more severe Arg20Cys variant; mutant cells show reduced COX6B1 steady-state levels, poor incorporation into holoenzyme, and reduced complex IV activity, rescued by WT COX6B1 expression.	(sinkler2017tissueandconditionspecific pages 8-9, cunatova2020roleofcytochrome pages 10-11, sinkler2017tissueandconditionspecific pages 3-5)
Recent applications (biomarker / prognostic)	Recent studies use COX6B1 in translational contexts mainly as a biomarker/prognostic-gene component rather than a validated standalone clinical marker.	In 2024 uveal melanoma, COX6B1 was one of 9 OXPHOS-related genes in a prognostic model built from 80 TCGA-UVM cases, with 1–5 year AUC values all >0.88 and external validation in GSE22138/GSE39717; a 2023 dietary-restriction review also discusses Cox6b1 conceptually in complex IV/supercomplex regulation, but without COX6B1-specific quantitative biomarker metrics.	(zhan2024constructionofoxidative pages 1-2, zhan2024constructionofoxidative pages 2-4, shimokawa2023mechanismsunderlyingretardation pages 5-8)

Table: This table summarizes the main functional annotation points for human COX6B1, including identity, localization, molecular role, assembly biology, disease relevance, and recent translational uses. It is useful as a compact evidence map tied directly to the available context sources.

Key references (URLs and publication dates)

Čunátová K et al. Role of cytochrome c oxidase nuclear-encoded subunits in health and disease. Physiological Research. Nov 2020. https://doi.org/10.33549/physiolres.934446 (cunatova2020roleofcytochrome pages 7-8, cunatova2020roleofcytochrome pages 10-11)
Gladyck S et al. Regulation of COX assembly and function by twin CX9C proteins—implications for human disease. Cells. Jan 2021. https://doi.org/10.3390/cells10020197 (gladyck2021regulationofcox pages 12-13)
Sinkler CA et al. Tissue- and condition-specific isoforms of mammalian cytochrome c oxidase subunits: from function to human disease. Oxidative Medicine and Cellular Longevity. May 2017. https://doi.org/10.1155/2017/1534056 (sinkler2017tissueandconditionspecific pages 8-9, sinkler2017tissueandconditionspecific pages 1-2, sinkler2017tissueandconditionspecific pages 3-5)
Zhan Z et al. Construction of oxidative phosphorylation-related prognostic risk score model in uveal melanoma. BMC Ophthalmology. May 2024. https://doi.org/10.1186/s12886-024-03441-6 (zhan2024constructionofoxidative pages 1-2, zhan2024constructionofoxidative pages 2-4)
Shimada K et al. Disruption of testis-enriched cytochrome c oxidase subunit COX6B2 but not COX8C leads to subfertility. Experimental Animals. Jan 2024 (published online 10 Jul 2023). https://doi.org/10.1538/expanim.23-0055 (shimada2024disruptionoftestisenriched pages 1-2)
Shimokawa I. Mechanisms underlying retardation of aging by dietary energy restriction. Pathology International. Nov 2023. https://doi.org/10.1111/pin.13387 (shimokawa2023mechanismsunderlyingretardation pages 5-8)

Note: A mechanistic COX6B1 assembly preprint (bioRxiv, Jun 2025) provides detailed knockout/variant/rescue quantitation but is outside the requested 2023–2024 priority window; it is included only to contextualize the most explicit recent mechanistic model in the retrieved evidence. https://doi.org/10.1101/2025.03.25.645161 (cunatova2025cox6b1securesa pages 6-8)

References

(gladyck2021regulationofcox pages 12-13): Stephanie Gladyck, Siddhesh Aras, Maik Hüttemann, and Lawrence I. Grossman. Regulation of cox assembly and function by twin cx9c proteins—implications for human disease. Cells, 10:197, Jan 2021. URL: https://doi.org/10.3390/cells10020197, doi:10.3390/cells10020197. This article has 31 citations.
(cunatova2020roleofcytochrome pages 7-8): K Čunátová, D Pajuelo Reguera, J Houštěk, T Mráček, and P Pecina. Role of cytochrome c oxidase nuclear-encoded subunits in health and disease. Physiological Research, pages 947-965, Nov 2020. URL: https://doi.org/10.33549/physiolres.934446, doi:10.33549/physiolres.934446. This article has 52 citations and is from a peer-reviewed journal.
(sinkler2017tissueandconditionspecific pages 8-9): Christopher A. Sinkler, Hasini Kalpage, Joseph Shay, Icksoo Lee, Moh H. Malek, Lawrence I. Grossman, and Maik Hüttemann. Tissue- and condition-specific isoforms of mammalian cytochrome c oxidase subunits: from function to human disease. Oxidative Medicine and Cellular Longevity, May 2017. URL: https://doi.org/10.1155/2017/1534056, doi:10.1155/2017/1534056. This article has 153 citations.
(sinkler2017tissueandconditionspecific pages 1-2): Christopher A. Sinkler, Hasini Kalpage, Joseph Shay, Icksoo Lee, Moh H. Malek, Lawrence I. Grossman, and Maik Hüttemann. Tissue- and condition-specific isoforms of mammalian cytochrome c oxidase subunits: from function to human disease. Oxidative Medicine and Cellular Longevity, May 2017. URL: https://doi.org/10.1155/2017/1534056, doi:10.1155/2017/1534056. This article has 153 citations.
(cunatova2020roleofcytochrome media a8606d54): K Čunátová, D Pajuelo Reguera, J Houštěk, T Mráček, and P Pecina. Role of cytochrome c oxidase nuclear-encoded subunits in health and disease. Physiological Research, pages 947-965, Nov 2020. URL: https://doi.org/10.33549/physiolres.934446, doi:10.33549/physiolres.934446. This article has 52 citations and is from a peer-reviewed journal.
(zhan2024constructionofoxidative pages 1-2): Zhiyun Zhan, Kun Lin, and Tingting Wang. Construction of oxidative phosphorylation-related prognostic risk score model in uveal melanoma. BMC Ophthalmology, May 2024. URL: https://doi.org/10.1186/s12886-024-03441-6, doi:10.1186/s12886-024-03441-6. This article has 7 citations and is from a peer-reviewed journal.
(zhan2024constructionofoxidative pages 2-4): Zhiyun Zhan, Kun Lin, and Tingting Wang. Construction of oxidative phosphorylation-related prognostic risk score model in uveal melanoma. BMC Ophthalmology, May 2024. URL: https://doi.org/10.1186/s12886-024-03441-6, doi:10.1186/s12886-024-03441-6. This article has 7 citations and is from a peer-reviewed journal.
(shimada2024disruptionoftestisenriched pages 1-2): Keisuke Shimada, Yonggang Lu, and Masahito Ikawa. Disruption of testis-enriched cytochrome c oxidase subunit cox6b2 but not cox8c leads to subfertility. Experimental Animals, 73:1-10, Jan 2024. URL: https://doi.org/10.1538/expanim.23-0055, doi:10.1538/expanim.23-0055. This article has 10 citations and is from a peer-reviewed journal.
(shimokawa2023mechanismsunderlyingretardation pages 5-8): Isao Shimokawa. Mechanisms underlying retardation of aging by dietary energy restriction. Pathology International, 73:579-592, Nov 2023. URL: https://doi.org/10.1111/pin.13387, doi:10.1111/pin.13387. This article has 4 citations and is from a peer-reviewed journal.
(cunatova2025cox6b1securesa pages 6-8): Kristýna Čunátová, Marek Vrbacký, Michal Knězů, Alena Pecinová, Lukáš Alán, Josef Houštěk, Erika Fernández-Vizarra, Tomáš Mráček, and Petr Pecina. Cox6b1 secures a redox-sensitive step in early cytochrome c oxidase assembly. bioRxiv, Jun 2025. URL: https://doi.org/10.1101/2025.03.25.645161, doi:10.1101/2025.03.25.645161. This article has 0 citations.
(weraarpachai2012identificationandcharacterization pages 41-45): W Weraarpachai. Identification and characterization of novel genes involved in cytochrome c oxidase deficiencies. Unknown journal, 2012.
(cunatova2020roleofcytochrome pages 10-11): K Čunátová, D Pajuelo Reguera, J Houštěk, T Mráček, and P Pecina. Role of cytochrome c oxidase nuclear-encoded subunits in health and disease. Physiological Research, pages 947-965, Nov 2020. URL: https://doi.org/10.33549/physiolres.934446, doi:10.33549/physiolres.934446. This article has 52 citations and is from a peer-reviewed journal.
(sinkler2017tissueandconditionspecific pages 3-5): Christopher A. Sinkler, Hasini Kalpage, Joseph Shay, Icksoo Lee, Moh H. Malek, Lawrence I. Grossman, and Maik Hüttemann. Tissue- and condition-specific isoforms of mammalian cytochrome c oxidase subunits: from function to human disease. Oxidative Medicine and Cellular Longevity, May 2017. URL: https://doi.org/10.1155/2017/1534056, doi:10.1155/2017/1534056. This article has 153 citations.
(cunatova2020roleofcytochrome media 5dad9122): K Čunátová, D Pajuelo Reguera, J Houštěk, T Mráček, and P Pecina. Role of cytochrome c oxidase nuclear-encoded subunits in health and disease. Physiological Research, pages 947-965, Nov 2020. URL: https://doi.org/10.33549/physiolres.934446, doi:10.33549/physiolres.934446. This article has 52 citations and is from a peer-reviewed journal.
(cunatova2025cox6b1securesa pages 1-3): Kristýna Čunátová, Marek Vrbacký, Michal Knězů, Alena Pecinová, Lukáš Alán, Josef Houštěk, Erika Fernández-Vizarra, Tomáš Mráček, and Petr Pecina. Cox6b1 secures a redox-sensitive step in early cytochrome c oxidase assembly. bioRxiv, Jun 2025. URL: https://doi.org/10.1101/2025.03.25.645161, doi:10.1101/2025.03.25.645161. This article has 0 citations.

Artifacts

Edison artifact artifact-00

Citations

shimada2024disruptionoftestisenriched pages 1-2
shimokawa2023mechanismsunderlyingretardation pages 5-8
cunatova2020roleofcytochrome pages 10-11
zhan2024constructionofoxidative pages 1-2
cunatova2020roleofcytochrome pages 7-8
gladyck2021regulationofcox pages 12-13
sinkler2017tissueandconditionspecific pages 8-9
sinkler2017tissueandconditionspecific pages 1-2
zhan2024constructionofoxidative pages 2-4
weraarpachai2012identificationandcharacterization pages 41-45
sinkler2017tissueandconditionspecific pages 3-5
https://doi.org/10.33549/physiolres.934446
https://doi.org/10.3390/cells10020197
https://doi.org/10.1155/2017/1534056
https://doi.org/10.1186/s12886-024-03441-6
https://doi.org/10.1538/expanim.23-0055
https://doi.org/10.1111/pin.13387
https://doi.org/10.1101/2025.03.25.645161
https://doi.org/10.3390/cells10020197,
https://doi.org/10.33549/physiolres.934446,
https://doi.org/10.1155/2017/1534056,
https://doi.org/10.1186/s12886-024-03441-6,
https://doi.org/10.1538/expanim.23-0055,
https://doi.org/10.1111/pin.13387,
https://doi.org/10.1101/2025.03.25.645161,

📄 View Raw YAML

id: P14854
gene_symbol: COX6B1
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: >-
  Cytochrome c oxidase subunit 6B1 (COX6B1) is a nuclear-encoded, peripheral intermembrane-side subunit
  of mitochondrial Complex IV. It is part of the mature 14-subunit cytochrome c oxidase complex and
  contributes structurally to normal Complex IV assembly/stability and activity, but it is not one
  of the mtDNA-encoded catalytic redox subunits. Existing annotations should therefore keep Complex
  IV membership and electron-transport participation while avoiding assignment of independent cytochrome-c
  oxidase catalytic activity to COX6B1 alone. Pathogenic variants cause mitochondrial Complex IV deficiency,
  nuclear type 7.
existing_annotations:
  - term:
      id: GO:0045277
      label: respiratory chain complex IV
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    qualifier: part_of
    review:
      summary: >-
        COX6B1 is a bona fide subunit of respiratory chain Complex IV, supported by the intact human
        Complex IV structure and ComplexPortal annotation. The 3.3 Å cryo-EM structure (PDB 5Z62) of
        the 14-subunit human Complex IV places COX6B1 in the assembled holoenzyme.
      action: ACCEPT
      reason: >-
        Core complex-membership annotation.
      supported_by:
        - reference_id: PMID:30030519
          supporting_text: >-
            we obtained the entire CIV structure containing 14 subunits, which includes the extra
            subunit NDUFA4
  - term:
      id: GO:0005739
      label: mitochondrion
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    qualifier: is_active_in
    review:
      summary: >-
        COX6B1 is a mitochondrial protein as part of mitochondrial cytochrome c oxidase.
      action: ACCEPT
      reason: >-
        Correct broad localization.
  - term:
      id: GO:0005743
      label: mitochondrial inner membrane
    evidence_type: IBA
    original_reference_id: GO_REF:0000033
    qualifier: is_active_in
    review:
      summary: >-
        COX6B1 associates with Complex IV at the mitochondrial inner membrane on the intermembrane-space
        side.
      action: ACCEPT
      reason: >-
        Correct localization for a peripheral membrane subunit of Complex IV.
  - term:
      id: GO:0005739
      label: mitochondrion
    evidence_type: IEA
    original_reference_id: GO_REF:0000002
    qualifier: located_in
    review:
      summary: >-
        COX6B1 is a mitochondrial protein as part of mitochondrial cytochrome c oxidase.
      action: ACCEPT
      reason: >-
        Correct broad localization.
  - term:
      id: GO:0005743
      label: mitochondrial inner membrane
    evidence_type: IEA
    original_reference_id: GO_REF:0000120
    qualifier: located_in
    review:
      summary: >-
        COX6B1 associates with Complex IV at the mitochondrial inner membrane on the intermembrane-space
        side.
      action: ACCEPT
      reason: >-
        Correct localization for a peripheral membrane subunit of Complex IV.
  - term:
      id: GO:0045277
      label: respiratory chain complex IV
    evidence_type: IEA
    original_reference_id: GO_REF:0000120
    qualifier: part_of
    review:
      summary: >-
        COX6B1 is a bona fide subunit of respiratory chain Complex IV, supported by the intact human
        Complex IV structure and ComplexPortal annotation. The 3.3 Å cryo-EM structure (PDB 5Z62) of
        the 14-subunit human Complex IV places COX6B1 in the assembled holoenzyme.
      action: ACCEPT
      reason: >-
        Core complex-membership annotation.
      supported_by:
        - reference_id: PMID:30030519
          supporting_text: >-
            we obtained the entire CIV structure containing 14 subunits, which includes the extra
            subunit NDUFA4
  - term:
      id: GO:1902600
      label: proton transmembrane transport
    evidence_type: IEA
    original_reference_id: GO_REF:0000108
    qualifier: involved_in
    review:
      summary: >-
        Complex IV pumps protons, but COX6B1 is not itself the proton-translocation path or catalytic
        core. The automated inference projects a whole-complex process onto a peripheral subunit.
      action: MARK_AS_OVER_ANNOTATED
      reason: |
        Over-annotated at the individual gene-product level. The appropriate core statement is Complex
        IV membership and contribution to the complex-level activity. Falcon deep research confirms
        COX6B1 is a small accessory subunit, not a catalytic/proton-translocation component, and that
        its loss does not change proton stoichiometry (only enzyme activity and cooperativity).
      supported_by:
        - reference_id: file:human/COX6B1/COX6B1-deep-research-falcon.md
          supporting_text: |
            Experimental removal/loss of COX6B1 (e.g., during mild solubilization) leads to **monomerization** of COX and is associated with a **~two-fold increase in enzyme activity** without changing proton stoichiometry, interpreted as loss of inter-monomer cooperativity and altered cytochrome c binding kinetics.
  - term:
      id: GO:0006119
      label: oxidative phosphorylation
    evidence_type: IEA
    original_reference_id: GO_REF:0000041
    qualifier: involved_in
    review:
      summary: >-
        COX6B1 participates in oxidative phosphorylation through Complex IV, but the term is broader
        than the gene product's specific role. The 3.3 Å cryo-EM structure (PDB 5Z62) of the
        14-subunit human Complex IV places COX6B1 within the assembled terminal oxidase of the
        electron transport chain.
      action: KEEP_AS_NON_CORE
      reason: >-
        Keep as a broad pathway-level annotation, not the core function statement.
      supported_by:
        - reference_id: PMID:30030519
          supporting_text: >-
            CIV is the terminal oxidase of the electron transport chain in mitochondria.
        - reference_id: file:human/COX6B1/COX6B1-deep-research-falcon.md
          supporting_text: |
            COX6B1 functions within the **oxidative phosphorylation** pathway as a complex IV accessory subunit that contributes to **quaternary structure** (dimerization) and is linked to **assembly/biogenesis** of the complex.
  - term:
      id: GO:0006123
      label: mitochondrial electron transport, cytochrome c to oxygen
    evidence_type: NAS
    original_reference_id: PMID:30030519
    qualifier: involved_in
    review:
      summary: >-
        COX6B1 participates in cytochrome-c-to-oxygen electron transport as part of the intact Complex
        IV holoenzyme.
      action: ACCEPT
      reason: >-
        Correct complex-level process annotation for a structural Complex IV subunit.
      supported_by:
        - reference_id: PMID:30030519
          supporting_text: >-
            CIV is the terminal oxidase of the electron transport chain in mitochondria.
        - reference_id: file:human/COX6B1/COX6B1-deep-research-falcon.md
          supporting_text: |
            Cytochrome c oxidase (complex IV; COX/CCO) is the terminal enzyme of the mitochondrial electron transport chain. Its catalytic core transfers electrons from cytochrome c to molecular oxygen and contributes to the proton gradient used for ATP synthesis.
  - term:
      id: GO:0031966
      label: mitochondrial membrane
    evidence_type: IDA
    original_reference_id: PMID:30030519
    qualifier: located_in
    review:
      summary: >-
        Mitochondrial membrane is a correct broader localization for a peripheral inner-membrane Complex
        IV subunit.
      action: ACCEPT
      reason: >-
        Accept as correct but less specific than mitochondrial inner membrane.
      supported_by:
        - reference_id: PMID:30030519
          supporting_text: >-
            Current opinions point out that CIV exists in two states under physiological conditions,
            either being assembled into supercomplexes or freely scattered on mitochondrial inner
            membrane.
  - term:
      id: GO:0045277
      label: respiratory chain complex IV
    evidence_type: IPI
    original_reference_id: PMID:30030519
    qualifier: part_of
    review:
      summary: >-
        COX6B1 is a bona fide subunit of respiratory chain Complex IV, supported by the intact human
        Complex IV structure and ComplexPortal annotation.
      action: ACCEPT
      reason: >-
        Core complex-membership annotation.
      supported_by:
        - reference_id: PMID:30030519
          supporting_text: >-
            we obtained the entire CIV structure containing 14 subunits, which includes the extra
            subunit NDUFA4
        - reference_id: file:human/COX6B1/COX6B1-deep-research-falcon.md
          supporting_text: |
            COX6B1 is **not catalytic**; it is a **small, nuclear-encoded accessory subunit** that modulates structure/assembly and function of the complex.
  - term:
      id: GO:0045333
      label: cellular respiration
    evidence_type: NAS
    original_reference_id: PMID:30030519
    qualifier: involved_in
    review:
      summary: >-
        Cellular respiration is correct at the pathway level but too broad for the specific COX6B1
        role.
      action: KEEP_AS_NON_CORE
      reason: >-
        Keep as non-core.
  - term:
      id: GO:0005739
      label: mitochondrion
    evidence_type: IDA
    original_reference_id: GO_REF:0000052
    qualifier: located_in
    review:
      summary: >-
        COX6B1 is a mitochondrial protein as part of mitochondrial cytochrome c oxidase.
      action: ACCEPT
      reason: >-
        Correct broad localization.
  - term:
      id: GO:0005743
      label: mitochondrial inner membrane
    evidence_type: EXP
    original_reference_id: PMID:30030519
    qualifier: located_in
    review:
      summary: >-
        COX6B1 associates with Complex IV at the mitochondrial inner membrane on the intermembrane-space
        side.
      action: ACCEPT
      reason: >-
        Correct localization for a peripheral membrane subunit of Complex IV.
      supported_by:
        - reference_id: PMID:30030519
          supporting_text: >-
            Current opinions point out that CIV exists in two states under physiological conditions,
            either being assembled into supercomplexes or freely scattered on mitochondrial inner
            membrane.
        - reference_id: file:human/COX6B1/COX6B1-deep-research-falcon.md
          supporting_text: |
            COX6B1 is positioned on the **intermembrane-space (IMS)-facing side** of complex IV. Structural placement from reviews and figure evidence shows COX6B1 exposed on the IMS side and situated at/near the **dimer interface**.
  - term:
      id: GO:0005739
      label: mitochondrion
    evidence_type: HTP
    original_reference_id: PMID:34800366
    qualifier: located_in
    review:
      summary: >-
        COX6B1 is a mitochondrial protein as part of mitochondrial cytochrome c oxidase.
      action: ACCEPT
      reason: >-
        Correct broad localization.
      supported_by:
        - reference_id: file:human/COX6B1/COX6B1-uniprot.txt
          supporting_text: >-
            SUBCELLULAR LOCATION: Mitochondrion
  - term:
      id: GO:0021762
      label: substantia nigra development
    evidence_type: HEP
    original_reference_id: PMID:22926577
    qualifier: involved_in
    review:
      summary: >-
        The substantia nigra development annotation comes from phenotype/proteomic evidence and does
        not describe the core molecular role of COX6B1.
      action: KEEP_AS_NON_CORE
      reason: >-
        Keep as non-core/phenotype-associated rather than a primary gene function.
  - term:
      id: GO:0005743
      label: mitochondrial inner membrane
    evidence_type: TAS
    original_reference_id: Reactome:R-HSA-163214
    qualifier: located_in
    review:
      summary: >-
        COX6B1 associates with Complex IV at the mitochondrial inner membrane on the intermembrane-space
        side.
      action: ACCEPT
      reason: >-
        Correct localization for a peripheral membrane subunit of Complex IV.
  - term:
      id: GO:0005743
      label: mitochondrial inner membrane
    evidence_type: TAS
    original_reference_id: Reactome:R-HSA-9709406
    qualifier: located_in
    review:
      summary: >-
        COX6B1 associates with Complex IV at the mitochondrial inner membrane on the intermembrane-space
        side.
      action: ACCEPT
      reason: >-
        Correct localization for a peripheral membrane subunit of Complex IV.
  - term:
      id: GO:0005743
      label: mitochondrial inner membrane
    evidence_type: TAS
    original_reference_id: Reactome:R-HSA-9865663
    qualifier: located_in
    review:
      summary: >-
        COX6B1 associates with Complex IV at the mitochondrial inner membrane on the intermembrane-space
        side.
      action: ACCEPT
      reason: >-
        Correct localization for a peripheral membrane subunit of Complex IV.
  - term:
      id: GO:0004129
      label: cytochrome-c oxidase activity
    evidence_type: NAS
    original_reference_id: PMID:2172092
    qualifier: enables
    review:
      summary: >-
        Cytochrome-c oxidase activity is the activity of the assembled Complex IV enzyme. COX6B1 contributes
        to this activity as a subunit but does not independently catalyze electron transfer or oxygen
        reduction.
      action: MARK_AS_OVER_ANNOTATED
      reason: |
        Classic example of whole-complex activity being over-attributed to a non-catalytic subunit.
        Represent this as contributes_to in the synthesized core function, not as independently enabled
        activity. Falcon deep research corroborates that COX6B1 is "not catalytic" and is instead a
        nuclear-encoded accessory subunit that modulates complex structure/assembly and function.
      supported_by:
        - reference_id: file:human/COX6B1/COX6B1-deep-research-falcon.md
          supporting_text: |
            COX6B1 is **not catalytic**; it is a **small, nuclear-encoded accessory subunit** that modulates structure/assembly and function of the complex.
core_functions:
  - description: >-
      COX6B1 is a peripheral intermembrane-side structural/accessory subunit of mitochondrial Complex
      IV that bridges the two monomers at the dimer interface and supports cooperative cytochrome c
      binding kinetics. It contributes to the complex-level cytochrome-c oxidase activity and
      electron-transport process by supporting the assembled holoenzyme, and is also required for an
      early redox-sensitive step in Complex IV biogenesis (MT-CO2 maturation/metalation). Cytochrome-c
      oxidase catalytic activity should not be attributed to COX6B1 alone.
    contributes_to_molecular_function:
      id: GO:0004129
      label: cytochrome-c oxidase activity
    directly_involved_in:
      - id: GO:0006123
        label: mitochondrial electron transport, cytochrome c to oxygen
    locations:
      - id: GO:0005743
        label: mitochondrial inner membrane
    in_complex:
      id: GO:0045277
      label: respiratory chain complex IV
    supported_by:
      - reference_id: PMID:30030519
        supporting_text: >-
          we obtained the entire CIV structure containing 14 subunits, which includes the extra subunit
          NDUFA4
      - reference_id: file:human/COX6B1/COX6B1-uniprot.txt
        supporting_text: >-
          Component of the cytochrome c oxidase (complex IV, CIV), a multisubunit enzyme composed
          of 14 subunits. SUBCELLULAR LOCATION: Mitochondrion inner membrane; Peripheral membrane
          protein; Intermembrane side.
      - reference_id: file:human/COX6B1/COX6B1-deep-research-falcon.md
        supporting_text: |
          A consistent model is that COX6B1 **bridges the two monomers** in the COX dimer and supports dimer stability and cooperative function.
      - reference_id: file:human/COX6B1/COX6B1-deep-research-falcon.md
        supporting_text: |
          COX6B1 is **not catalytic**; it is a **small, nuclear-encoded accessory subunit** that modulates structure/assembly and function of the complex.
references:
  - id: GO_REF:0000002
    title: Gene Ontology annotation through association of InterPro records with GO terms
    findings:
      - statement: InterPro2GO mapping (COX6B family domains) propagates mitochondrial and
          Complex IV-related annotations to COX6B1.
  - id: GO_REF:0000033
    title: Annotation inferences using phylogenetic trees
    findings:
      - statement: PAINT/IBA phylogenetic propagation supports Complex IV membership,
          mitochondrial inner-membrane localization, and cytochrome-c-to-O2 electron
          transport for COX6B1 across COX6B orthologs.
  - id: GO_REF:0000041
    title: Gene Ontology annotation based on UniPathway vocabulary mapping
    findings:
      - statement: UniPathway UPA00705 (oxidative phosphorylation) propagates participation
          in the OXPHOS pathway to COX6B1.
  - id: GO_REF:0000052
    title: Gene Ontology annotation based on curation of immunofluorescence data
    findings:
      - statement: Curated immunofluorescence data (Human Protein Atlas) place COX6B1
          in mitochondria.
  - id: GO_REF:0000108
    title: Automatic assignment of GO terms using logical inference, based on on inter-ontology
      links
    findings:
      - statement: Logical inference from cytochrome-c oxidase activity (GO:0004129)
          propagates proton transmembrane transport (GO:1902600) to Complex IV
          subunits including COX6B1.
  - id: GO_REF:0000120
    title: Combined Automated Annotation using Multiple IEA Methods
    findings:
      - statement: Combined automated IEA methods propagate inner mitochondrial
          membrane localization and Complex IV membership to COX6B1.
  - id: PMID:2172092
    title: Isolation of cDNAs encoding subunit VIb of cytochrome c oxidase and steady-state
      levels of coxVIb mRNA in different tissues.
    findings:
      - statement: Cloned cDNAs encoding human cytochrome c oxidase subunit VIb (COX6B1) and
          characterized tissue-specific steady-state mRNA levels, identifying COX6B1 as a
          subunit of cytochrome c oxidase.
        supporting_text: Isolation of cDNAs encoding subunit VIb of cytochrome c oxidase
          and steady-state levels of coxVIb mRNA in different tissues.
  - id: PMID:22926577
    title: Quantitative proteomic analysis of human substantia nigra in Alzheimer's disease,
      Huntington's disease and Multiple sclerosis.
    findings:
      - statement: Quantitative proteomics of human substantia nigra in neurodegenerative
          disease detected COX6B1, used to underpin a substantia-nigra-development
          phenotype association (HEP evidence).
        supporting_text: Quantitative proteomic analysis of human substantia nigra in
          Alzheimer's disease, Huntington's disease and Multiple sclerosis.
  - id: PMID:30030519
    title: Structure of the intact 14-subunit human cytochrome c oxidase.
    findings:
      - statement: >-
          Cryo-EM structure (3.3 Å, PDB 5Z62) of human Complex IV confirms COX6B1 as a
          subunit of the intact 14-subunit holoenzyme on the intermembrane-space side
          and resolves its position at the dimer interface.
        supporting_text: we obtained the entire CIV structure containing 14 subunits, which
          includes the extra subunit NDUFA4
    reference_review:
      relevance: HIGH
      correctness: VERIFIED
      review_notes: >-
        PubMed-verified 3.3 Å cryo-EM structure of intact human Complex IV (PDB 5Z62) confirming
        COX6B1 membership in the assembled 14-subunit holoenzyme.
  - id: PMID:34800366
    title: Quantitative high-confidence human mitochondrial proteome and its dynamics in
      cellular context.
    findings:
      - statement: High-confidence mitochondrial proteome identifies COX6B1 as a mitochondrial
          protein.
        supporting_text: Quantitative high-confidence human mitochondrial proteome
          and its dynamics in cellular context.
  - id: Reactome:R-HSA-163214
    title: Electron transfer from reduced cytochrome c to molecular oxygen
    findings:
      - statement: Reactome pathway describing Complex IV electron transfer from reduced
          cytochrome c to O2 places COX6B1 in the inner mitochondrial membrane as a CIV
          subunit.
        supporting_text: Electron transfer from reduced cytochrome c to molecular oxygen
  - id: Reactome:R-HSA-9709406
    title: CO binds to Cytochrome c oxidase
    findings:
      - statement: Reactome pathway describing carbon monoxide binding to CIV places
          COX6B1 in the inner mitochondrial membrane as part of the target enzyme.
        supporting_text: CO binds to Cytochrome c oxidase
  - id: Reactome:R-HSA-9865663
    title: MT-CO3, COX6A,B,7A and NDUFA4 bind to holo-MT-CO1,2 complex
    findings:
      - statement: Reactome CIV assembly step in which COX6A, COX6B (including COX6B1), COX7A
          and NDUFA4 join the holo-MT-CO1,2 complex; places COX6B1 in the inner
          mitochondrial membrane during late CIV assembly.
        supporting_text: MT-CO3, COX6A,B,7A and NDUFA4 bind to holo-MT-CO1,2 complex
  - id: file:human/COX6B1/COX6B1-deep-research-falcon.md
    title: Falcon deep research for human COX6B1
    findings:
      - statement: |
          COX6B1 is a small, nuclear-encoded accessory subunit of mitochondrial Complex IV and is not a
          catalytic component; it modulates structure, assembly, and function of the complex.
        supporting_text: |
          COX6B1 is **not catalytic**; it is a **small, nuclear-encoded accessory subunit** that modulates structure/assembly and function of the complex.
        reference_section_type: OTHER
      - statement: |
          COX6B1 is positioned on the intermembrane-space (IMS)-facing side of Complex IV at the dimer
          interface.
        supporting_text: |
          COX6B1 is positioned on the **intermembrane-space (IMS)-facing side** of complex IV. Structural placement from reviews and figure evidence shows COX6B1 exposed on the IMS side and situated at/near the **dimer interface**.
        reference_section_type: OTHER
      - statement: |
          COX6B1 bridges the two monomers of the COX dimer and supports dimer stability and cooperative
          function; loss leads to monomerization and ~2-fold increase in enzyme activity without
          changing proton stoichiometry.
        supporting_text: |
          Experimental removal/loss of COX6B1 (e.g., during mild solubilization) leads to **monomerization** of COX and is associated with a **~two-fold increase in enzyme activity** without changing proton stoichiometry, interpreted as loss of inter-monomer cooperativity and altered cytochrome c binding kinetics.
        reference_section_type: OTHER
      - statement: |
          Cytochrome c oxidase is the terminal enzyme of the mitochondrial electron transport chain,
          transferring electrons from cytochrome c to molecular oxygen and contributing to the proton
          gradient used for ATP synthesis.
        supporting_text: |
          Cytochrome c oxidase (complex IV; COX/CCO) is the terminal enzyme of the mitochondrial electron transport chain. Its catalytic core transfers electrons from cytochrome c to molecular oxygen and contributes to the proton gradient used for ATP synthesis.
        reference_section_type: OTHER
      - statement: |
          COX6B1 functions within the oxidative phosphorylation pathway as a Complex IV accessory
          subunit contributing to quaternary structure (dimerization) and assembly/biogenesis.
        supporting_text: |
          COX6B1 functions within the **oxidative phosphorylation** pathway as a complex IV accessory subunit that contributes to **quaternary structure** (dimerization) and is linked to **assembly/biogenesis** of the complex.
        reference_section_type: OTHER
      - statement: |
          Recent KO/complementation evidence indicates COX6B1 is essential for an early, redox-sensitive
          step in Complex IV biogenesis, particularly affecting MT-CO2 maturation/metalation with
          altered copper-delivery/assembly factors (COA6, SCO1, SCO2).
        supporting_text: |
          More recent mechanistic work (preprint) using COX6B1 knockout/complementation in human cells argues COX6B1 is also essential for an **early, redox-sensitive step** in biogenesis—particularly affecting **MT-CO2 maturation/metalation**, with altered abundance/association of copper-delivery/assembly factors (e.g., COA6/SCO1/SCO2).
        reference_section_type: OTHER
      - statement: |
          Pathogenic homozygous missense variants in a conserved N-terminal arginine (R19/R20)
          cause infantile/early-onset encephalomyopathy with isolated Complex IV deficiency; severe
          cases include hydrocephalus and hypertrophic cardiomyopathy.
        supporting_text: |
          Pathogenic **homozygous missense** variants in a conserved arginine in the N-terminus region are repeatedly highlighted. Depending on numbering conventions these appear as **R19H/R19C** or **R20H/R20C**. Reported phenotypes include **infantile/early-onset encephalomyopathy** with isolated complex IV deficiency; more severe presentations include **hydrocephalus** and **hypertrophic cardiomyopathy** (notably with Arg→Cys).
        reference_section_type: OTHER
      - statement: |
          Patient fibroblasts and muscle with Arg20His show reduced COX6B1 steady-state levels,
          decreased incorporation into assembling Complex IV, and accumulation of assembly intermediate
          S3; wild-type COX6B1 complementation restores Complex IV content and activity.
        supporting_text: |
          A 2020 review summarizes evidence that patient fibroblasts and muscle with **Arg20His** show reduced COX6B1 steady-state levels and decreased incorporation into assembling complex IV, with accumulation of assembly intermediate **S3** and selective reduction in complex IV activity (other OXPHOS complexes relatively unaffected). Importantly, **wild-type COX6B1 complementation restores** complex IV content and activity, supporting causality.
        reference_section_type: OTHER
      - statement: |
          The somatic COX6B1 isoform is distinct from the testis-enriched paralog COX6B2; identity and
          isoform context are important for interpreting reproductive/cancer studies.
        supporting_text: |
          COX VIb exists as (at least) a broadly expressed somatic isoform (**COX6B1**) and a testis-enriched isoform (**COX6B2**). This matters for interpretation of studies in reproductive tissues and cancers where COX6B2 may be induced.
        reference_section_type: OTHER
suggested_questions:
  - question: >-
      Beyond the dimer-bridging structural role captured by current GO terms, does
      COX6B1 enable a specific, early redox-sensitive step in MT-CO2 maturation /
      copper-delivery (via COA6 / SCO1 / SCO2)? Confirming this would justify a more
      specific "mitochondrial respiratory chain complex IV assembly" annotation and
      ideally an MT-CO2-metalation-related BP child term.
  - question: >-
      Are the R19/R20 N-terminal arginine variants (R19H/R19C or R20H/R20C) causing
      pathology because they destabilize the COX6B1 fold, prevent incorporation into
      assembly intermediate S3, or specifically disrupt CIV dimerization at the
      intermembrane-space face? Distinguishing among these would refine the
      functional consequence (assembly vs. dimerization vs. catalytic cooperativity).
  - question: >-
      Why does loss of COX6B1 lead to a ~2-fold rise in monomeric CIV enzyme activity
      in vitro yet manifest as isolated Complex IV deficiency in patients? Is the in
      vivo bottleneck CIV assembly failure (low steady-state holoenzyme), loss of
      supercomplex stabilization, or loss of negative-cooperative regulation needed to
      match O2 reduction to electron supply?
suggested_experiments:
  - description: >-
      Cryo-EM of human Complex IV reconstituted with R19H/R20H/R20C COX6B1 variants
      alongside an in vitro CIV assembly assay using CRISPR COX6B1-KO HEK293 mitochondria
      complemented with WT vs. variant COX6B1. Quantify CIV holoenzyme levels by BN-PAGE,
      assembly-intermediate occupancy (S1/S2/S3), MT-CO2 metalation status (Cu content +
      SCO1/SCO2 co-IP), and respirometry.
    hypothesis: >-
      R19/R20 variants act primarily by blocking incorporation of COX6B1 into the S3
      assembly intermediate and impair MT-CO2 copper delivery, rather than by destabilizing
      the assembled dimer interface.
    experiment_type: structural biology / mitochondrial biochemistry
  - description: >-
      Native single-particle cytochrome c kinetic analyses of isolated dimeric versus
      monomeric COX from WT and COX6B1-KO human cells, pairing this with high-resolution
      respirometry under physiological cytochrome c concentrations and at varying
      ATP/ADP ratios.
    hypothesis: >-
      The 2-fold activity gain of monomeric CIV in vitro reflects loss of negative
      cooperativity that is essential in vivo for matching CIV turnover to upstream
      electron supply; under physiological cytochrome c and energy-charge constraints,
      monomeric CIV under-performs.
    experiment_type: enzyme kinetics / respirometry
  - description: >-
      Patient-derived iPSC differentiation to cardiomyocytes and cortical/spinal neurons
      from R19H/R20C COX6B1 patients vs. isogenic CRISPR-corrected controls. Assess
      CIV assembly (BN-PAGE), MT-CO2 maturation, supercomplex content, respirometry,
      ROS, and Ca2+ handling; pair with proteomic interactome mapping of COA6/SCO1/SCO2
      around COX6B1.
    hypothesis: >-
      Patient cardiomyocytes show selective Complex IV assembly failure and MT-CO2
      hypo-metalation that is rescued by wild-type COX6B1, with a steeper bioenergetic
      penalty than fibroblasts owing to higher CIV turnover demand.
    experiment_type: stem-cell biology / clinical model

Gene Description

Existing Annotations Review

Core Functions

References

Suggested Questions for Experts

Suggested Experiments

Deep Research

Falcon

Research report: Human COX6B1 (UniProt P14854) — functional annotation and recent literature

0. Target verification (mandatory)

1. Key concepts, definitions, and current understanding

1.1 Cytochrome c oxidase (complex IV) and what COX6B1 is (and is not)

1.2 Subcellular localization and topology

1.3 COX dimerization, cooperativity, and cytochrome c interaction kinetics

1.4 Isoforms and paralogs

2. Recent developments and latest research (prioritizing 2023–2024)

2.1 2024: COX6B1 as part of OXPHOS-based prognostic models (uveal melanoma)

2.2 2024: Isoform context from mouse genetics (COX6B2) and implications for interpreting COX6B1

2.3 2023: Conceptual linkage of Cox6b1 to supercomplex biology during dietary restriction

2.4 Important caveat about “latest mechanistic” COX6B1 literature

3. Primary function, biological processes, and pathways

3.1 Pathway context: oxidative phosphorylation and complex IV biogenesis

3.2 Assembly biology: late incorporation model vs essential early checkpoint

3.3 Structural placement and interfaces (expert synthesis)

4. Disease relevance (clinical genetics and mechanisms)

4.1 Pathogenic variants and clinical phenotypes

4.2 Molecular mechanism in patient-derived material

5. Current applications and real-world implementations

5.1 Clinical testing / diagnostics

5.2 Cancer and systems-biology applications

5.3 Model systems for functional dissection

6. Relevant statistics and quantitative findings (from the retrieved sources)

7. Visual evidence (figures/tables)

8. Evidence map (summary table)

Key references (URLs and publication dates)

Artifacts

Citations

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