UQCRB (ubiquinol-cytochrome c reductase binding protein; also QP-C / cytochrome b-c1 complex subunit 7 / QCR7) is a small (~13.5 kDa, 111 aa) nuclear-encoded, non-catalytic structural subunit of mitochondrial respiratory Complex III (the cytochrome b-c1 complex / ubiquinol-cytochrome c oxidoreductase). It is one of the low-molecular-weight subunits of the 11-subunit complex; the redox catalysis of Complex III is carried out by the catalytic subunits cytochrome b, the Rieske iron-sulfur protein (UQCRFS1) and cytochrome c1, whereas UQCRB contributes to assembly and structural integrity of the complex rather than to catalysis. Complex III is an obligate dimer embedded as a peripheral protein on the matrix side of the mitochondrial inner membrane, and it associates with Complex I and Complex IV to form respiratory supercomplexes and megacomplexes. Within the electron transport chain, Complex III transfers electrons from ubiquinol to cytochrome c, coupling this redox reaction to proton translocation across the inner membrane (the Q cycle) and thereby contributing to oxidative phosphorylation and aerobic respiration. UQCRB was originally proposed to be the ubiquinone-binding protein, but this ubiquinone-binding role is no longer considered established. Loss-of-function variants in UQCRB cause mitochondrial complex III deficiency (nuclear type 3), a mitochondrial disorder that can present with hypoglycemia and lactic acidosis.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
|
GO:0045275
respiratory chain complex III
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: Phylogenetic (IBA) annotation placing UQCRB as part of respiratory chain complex III. This is the defining, well-established localization/membership of this subunit and is supported by cryo-EM structures of human Complex III and by UniProt.
Reason: UQCRB is a bona fide low-molecular-weight subunit of the cytochrome b-c1 complex (Complex III). This is confirmed structurally and by the family definition, and the complex membership is a core aspect of the gene's function.
Supporting Evidence:
file:human/UQCRB/UQCRB-uniprot.txt
Component of the ubiquinol-cytochrome c oxidoreductase, a
|
|
GO:0006122
mitochondrial electron transport, ubiquinol to cytochrome c
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: Phylogenetic (IBA) annotation to the specific Complex III process, transfer of electrons from ubiquinol to cytochrome c. As a structural subunit of Complex III, UQCRB participates in this process.
Reason: This is the core biological process of Complex III and the most appropriate specific BP term for a CIII subunit. Well supported by the complex's catalytic role.
Supporting Evidence:
file:human/UQCRB/UQCRB-uniprot.txt
transfer from ubiquinol to cytochrome c, linking this redox reaction to
|
|
GO:0005743
mitochondrial inner membrane
|
IEA
GO_REF:0000044 |
ACCEPT |
Summary: Electronic annotation from UniProt Subcellular Location mapping placing UQCRB in the mitochondrial inner membrane. Consistent with its role as a peripheral inner-membrane Complex III subunit.
Reason: Complex III, and hence UQCRB, resides in the mitochondrial inner membrane. This is the correct, specific location and matches the UniProt subcellular location.
Supporting Evidence:
file:human/UQCRB/UQCRB-uniprot.txt
SUBCELLULAR LOCATION: Mitochondrion inner membrane
|
|
GO:0006122
mitochondrial electron transport, ubiquinol to cytochrome c
|
IEA
GO_REF:0000002 |
ACCEPT |
Summary: InterPro2GO electronic annotation to the Complex III electron transport process, based on the QCR7 family signatures (IPR003197, IPR036544). Duplicates the IBA/NAS annotations to the same specific BP.
Reason: The InterPro-to-GO mapping is appropriate for this family and points to the correct, specific Complex III process. Consistent with the experimental and phylogenetic evidence.
Supporting Evidence:
file:human/UQCRB/UQCRB-uniprot.txt
transfer from ubiquinol to cytochrome c, linking this redox reaction to
|
|
GO:0016020
membrane
|
IEA
GO_REF:0000117 |
MARK AS OVER ANNOTATED |
Summary: Generic ARBA machine-learning electronic annotation to "membrane". This is correct but far less informative than the specific mitochondrial inner membrane location that is also annotated.
Reason: "membrane" is a high-level parent of the specific and better-supported term mitochondrial inner membrane (GO:0005743). It is not wrong, but it is uninformatively general given more precise annotations exist.
Supporting Evidence:
file:human/UQCRB/UQCRB-uniprot.txt
SUBCELLULAR LOCATION: Mitochondrion inner membrane
|
|
GO:0045275
respiratory chain complex III
|
IEA
GO_REF:0000002 |
ACCEPT |
Summary: InterPro2GO electronic annotation for complex III membership based on the QCR7 family superfamily signature (IPR036544). Duplicates the IBA and experimental (ComplexPortal IPI) annotations to the same term.
Reason: Correct complex membership for a QCR7-family protein; consistent with structural and phylogenetic evidence.
Supporting Evidence:
file:human/UQCRB/UQCRB-uniprot.txt
Component of the ubiquinol-cytochrome c oxidoreductase, a
|
|
GO:0005515
protein binding
|
IPI
PMID:16189514 Towards a proteome-scale map of the human protein-protein in... |
MARK AS OVER ANNOTATED |
Summary: Large-scale protein-protein interaction (IntAct/IPI) annotation to the uninformative term "protein binding". From a high-throughput human interactome screen.
Reason: "protein binding" (GO:0005515) is an uninformative molecular function term that does not capture the actual, specific function of UQCRB. This is an experimental IntAct record, so it is retained rather than removed, but flagged as over-annotated per curation policy that discourages bare "protein binding".
|
|
GO:0005515
protein binding
|
IPI
PMID:25416956 A proteome-scale map of the human interactome network. |
MARK AS OVER ANNOTATED |
Summary: Large-scale interactome (HuRI / IPI) annotation to the uninformative term "protein binding".
Reason: Uninformative "protein binding" from a high-throughput interactome map. Retained as an experimental IntAct record but flagged as over-annotated; it does not describe UQCRB's specific structural function within Complex III.
|
|
GO:0005515
protein binding
|
IPI
PMID:28514442 Architecture of the human interactome defines protein commun... |
MARK AS OVER ANNOTATED |
Summary: Large-scale interactome (BioPlex / IPI) annotation to the uninformative term "protein binding".
Reason: Uninformative "protein binding" from a high-throughput interactome study. Retained as an experimental IntAct record but flagged as over-annotated.
|
|
GO:0005515
protein binding
|
IPI
PMID:32296183 A reference map of the human binary protein interactome. |
MARK AS OVER ANNOTATED |
Summary: Large-scale binary interactome (HuRI reference map / IPI) annotation to the uninformative term "protein binding".
Reason: Uninformative "protein binding" from a high-throughput binary interactome map. Retained as an experimental IntAct record but flagged as over-annotated.
|
|
GO:0005515
protein binding
|
IPI
PMID:32814053 Interactome Mapping Provides a Network of Neurodegenerative ... |
MARK AS OVER ANNOTATED |
Summary: Large-scale interactome (neurodegenerative-disease interactome / IPI) annotation to the uninformative term "protein binding".
Reason: Uninformative "protein binding" from a high-throughput interactome study. Retained as an experimental IntAct record but flagged as over-annotated.
|
|
GO:0005515
protein binding
|
IPI
PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling... |
MARK AS OVER ANNOTATED |
Summary: Large-scale interactome (BioPlex 3.0 dual-cell networks / IPI) annotation to the uninformative term "protein binding".
Reason: Uninformative "protein binding" from a high-throughput interactome study. Retained as an experimental IntAct record but flagged as over-annotated.
|
|
GO:0005515
protein binding
|
IPI
PMID:40205054 Multimodal cell maps as a foundation for structural and func... |
MARK AS OVER ANNOTATED |
Summary: Large-scale multimodal cell-map interactome (IPI) annotation to the uninformative term "protein binding".
Reason: Uninformative "protein binding" from a high-throughput interactome/cell-map study. Retained as an experimental IntAct record but flagged as over-annotated.
|
|
GO:0005743
mitochondrial inner membrane
|
ISS
GO_REF:0000024 |
ACCEPT |
Summary: Curator-judged sequence-similarity (ISS) transfer of the mitochondrial inner membrane location from the bovine ortholog (UniProtKB:P00128). Consistent with all other location evidence.
Reason: The inner-membrane localization is well established for Complex III subunits across species; the ISS transfer from the bovine QCR7 ortholog is appropriate and matches the specific, correct location.
Supporting Evidence:
file:human/UQCRB/UQCRB-uniprot.txt
SUBCELLULAR LOCATION: Mitochondrion inner membrane
|
|
GO:0005743
mitochondrial inner membrane
|
IDA
PMID:28844695 Architecture of Human Mitochondrial Respiratory Megacomplex ... |
ACCEPT |
Summary: Direct experimental (IDA, ComplexPortal) assignment of UQCRB to the mitochondrial inner membrane, based on the cryo-EM structure of the human respiratory megacomplex in which Complex III is resolved in the inner membrane.
Reason: Strong experimental support: the cryo-EM structure of the human MCI2III2IV2 megacomplex places the dimeric Complex III (and thus its UQCRB subunit) in the mitochondrial inner membrane. This is the core, specific location.
Supporting Evidence:
PMID:28844695
The MCI2III2IV2 forms a circular structure with the dimeric CIII located in the center, where it is surrounded by two copies each of CI and CIV.
|
|
GO:0006122
mitochondrial electron transport, ubiquinol to cytochrome c
|
NAS
PMID:28844695 Architecture of Human Mitochondrial Respiratory Megacomplex ... |
ACCEPT |
Summary: Non-traceable author statement (NAS, ComplexPortal) that UQCRB, as a Complex III subunit, is involved in mitochondrial electron transport from ubiquinol to cytochrome c.
Reason: This is the core, specific process of Complex III and is consistent with the IBA/InterPro annotations to the same term and with the structural characterization of the electron transport chain in this study.
Supporting Evidence:
PMID:28844695
Two cytochrome c (Cyt.c) molecules are positioned to accept electrons on the surface of the c1 state CIII dimer.
|
|
GO:0045275
respiratory chain complex III
|
IPI
PMID:28844695 Architecture of Human Mitochondrial Respiratory Megacomplex ... |
ACCEPT |
Summary: Experimental (IPI, ComplexPortal) assignment of UQCRB as part of respiratory chain complex III, based on the cryo-EM structure that resolves the individual subunits of human Complex III.
Reason: Direct structural evidence for UQCRB being a component of Complex III. Core complex membership annotation.
Supporting Evidence:
PMID:28844695
The structure not only reveals the precise assignment of individual subunits of human CI and CIII
|
|
GO:0045333
cellular respiration
|
NAS
PMID:28844695 Architecture of Human Mitochondrial Respiratory Megacomplex ... |
KEEP AS NON CORE |
Summary: Non-traceable author statement (NAS, ComplexPortal) annotating UQCRB to the broad process "cellular respiration".
Reason: Correct but general: cellular respiration is a broad parent process. The more specific and informative BP is mitochondrial electron transport, ubiquinol to cytochrome c (GO:0006122), which is separately annotated and represents the core function. Retained as valid but non-core.
Supporting Evidence:
file:human/UQCRB/UQCRB-uniprot.txt
electron transport chain which drives oxidative phosphorylation
|
|
GO:0005739
mitochondrion
|
HTP
PMID:34800366 Quantitative high-confidence human mitochondrial proteome an... |
ACCEPT |
Summary: High-throughput (HTP) proteomic identification of UQCRB in the mitochondrion, from a quantitative high-confidence human mitochondrial proteome (MitoCoP). Correct but less specific than the mitochondrial inner membrane location.
Reason: Reliable high-throughput evidence for mitochondrial localization. It is a general parent of the more specific inner-membrane location, but it is correct and independently corroborates the organellar assignment.
Supporting Evidence:
PMID:34800366
mitochondrial high-confidence proteome of >1,100 proteins (MitoCoP)
|
|
GO:0005743
mitochondrial inner membrane
|
TAS
Reactome:R-HSA-164651 |
ACCEPT |
Summary: Traceable author statement (Reactome) placing UQCRB in the mitochondrial inner membrane, associated with the reaction "Electron transfer from ubiquinol to cytochrome c of complex III".
Reason: Correct, specific location consistent with all other evidence. Reactome pathway context matches the Complex III role.
Supporting Evidence:
Reactome:R-HSA-164651
The protonmotive Q cycle is the mechanism by which complex III transfers electrons from ubiquinol to cytochrome c, linking this process to translocation of protons across the membrane.
|
|
GO:0005743
mitochondrial inner membrane
|
TAS
Reactome:R-HSA-9906017 |
ACCEPT |
Summary: Traceable author statement (Reactome) placing UQCRB in the mitochondrial inner membrane, in the context of Complex III assembly (proteolytic processing of the UQCRFS1 subunit).
Reason: Correct, specific location. The Reactome reaction concerns Complex III assembly in the inner membrane, consistent with UQCRB's structural/assembly role.
Supporting Evidence:
Reactome:R-HSA-9906017
Proteolytic processing is necessary for the correct insertion of UQCRFS1 in the complex III dimer.
|
|
GO:0005743
mitochondrial inner membrane
|
TAS
Reactome:R-HSA-9906042 |
ACCEPT |
Summary: Traceable author statement (Reactome) placing UQCRB in the mitochondrial inner membrane, in the context of Complex III maturation (TTC19 clearance of UQCRFS1 fragments).
Reason: Correct, specific location consistent with the Complex III assembly/maturation pathway context.
Supporting Evidence:
Reactome:R-HSA-9906042
N-terminal cleavage fragments of UQCRFS1 are cleared by TTC19, stabilizing the final complex.
|
|
GO:0006119
oxidative phosphorylation
|
TAS
PMID:3056408 Cloning and sequencing of a cDNA for human mitochondrial ubi... |
ACCEPT |
Summary: Traceable author statement (from the original human QP-C/UQCRB cDNA cloning paper) annotating involvement in oxidative phosphorylation, reflecting Complex III's role in driving OXPHOS via the electron transport chain.
Reason: Complex III is a core component of the electron transport chain that drives oxidative phosphorylation, so this is a valid process annotation for UQCRB. It is broader than the specific electron-transport step (GO:0006122) but correctly captures the downstream energetic role.
Supporting Evidence:
file:human/UQCRB/UQCRB-uniprot.txt
electron transport chain which drives oxidative phosphorylation
|
|
GO:0009060
aerobic respiration
|
TAS
PMID:3056408 Cloning and sequencing of a cDNA for human mitochondrial ubi... |
KEEP AS NON CORE |
Summary: Traceable author statement (original QP-C cDNA cloning paper) annotating involvement in aerobic respiration.
Reason: Correct but broad. Aerobic respiration is a high-level process; the core, specific function is captured by mitochondrial electron transport, ubiquinol to cytochrome c (GO:0006122). Retained as valid but non-core.
Supporting Evidence:
PMID:3056408
The ubiquinone-binding protein (QP-C) is a nuclear-encoded component of ubiquinol-cytochrome c oxidoreductase in the mitochondrial respiratory chain and plays an important role in electron transfer
|
|
GO:0098803
respiratory chain complex
|
TAS
PMID:3056408 Cloning and sequencing of a cDNA for human mitochondrial ubi... |
MARK AS OVER ANNOTATED |
Summary: Traceable author statement placing UQCRB in a respiratory chain complex, based on the original cDNA cloning paper identifying QP-C as a component of ubiquinol-cytochrome c oxidoreductase.
Reason: Correct but general: respiratory chain complex (GO:0098803) is a parent of the specific and better-supported term respiratory chain complex III (GO:0045275), which is annotated by IBA, InterPro and experimental (ComplexPortal IPI) evidence. Retained but flagged as over-general.
Supporting Evidence:
PMID:3056408
The ubiquinone-binding protein (QP-C) is a nuclear-encoded component of ubiquinol-cytochrome c oxidoreductase in the mitochondrial respiratory chain
|
|
GO:0005198
structural molecule activity
|
ISS
file:human/UQCRB/UQCRB-uniprot.txt |
NEW |
Summary: Proposed molecular function annotation. UQCRB has no informative molecular function in GOA (only the uninformative "protein binding" IPIs). As a non-catalytic subunit of Complex III, its molecular function is best captured as structural molecule activity, contributing to the structural integrity of the cytochrome b-c1 complex.
Reason: The catalytic activity of Complex III (electron transfer from ubiquinol to cytochrome c) is carried by cytochrome b, the Rieske iron-sulfur protein and cytochrome c1; UQCRB is a low-molecular-weight, non-catalytic structural subunit. Structural molecule activity (GO:0005198) is the appropriate subunit-specific molecular function, and it is not currently represented in GOA. No catalytic activity is asserted for UQCRB.
Supporting Evidence:
file:human/UQCRB/UQCRB-uniprot.txt
Component of the ubiquinol-cytochrome c oxidoreductase, a
|
Gene: UQCRB / UQBP; "Cytochrome b-c1 complex subunit 7" (QCR7); AltNames: Complex III subunit 7 / VII, QP-C,
"Ubiquinol-cytochrome c reductase complex 14 kDa protein". Human, taxon 9606. 111 aa, ~13.5 kDa.
Falcon deep research is OUT OF CREDITS (HTTP 402) — no -deep-research-falcon.md. Review grounded in the cached
UniProt record (UQCRB-uniprot.txt), the seeded GOA (UQCRB-goa.tsv), cached publications/PMID_*.md, cached
Reactome entries, and OLS term lookups.
GOA carries NO informative MF for UQCRB — the only MF term is GO:0005515 "protein binding" (IPI, from large-scale
interactome screens). Per project policy protein binding is uninformative and these IPIs are marked
MARK_AS_OVER_ANNOTATED (not REMOVE — they are experimental IntAct records whose full text I cannot verify).
For core_functions, the appropriate subunit-specific MF is structural molecule activity (GO:0005198) — this is
the schema-prescribed MF for a non-catalytic structural subunit ("contributes to the structural integrity of a
complex"), NOT an invented catalytic activity. It contributes_to the complex-level MF quinol-cytochrome-c
reductase activity (GO:0008121) enabled by the whole CIII.
Task prompt mentioned GO:0005750 for Complex III, but OLS confirms GO:0005750 is OBSOLETE ("obsolete
mitochondrial respiratory chain complex III"). The current, GOA-present complex term is GO:0045275 "respiratory
chain complex III" — used for in_complex. (GOA does not carry GO:0005750.)
id: P14927
gene_symbol: UQCRB
product_type: PROTEIN
status: INITIALIZED
taxon:
id: NCBITaxon:9606
label: Homo sapiens
description: >-
UQCRB (ubiquinol-cytochrome c reductase binding protein; also QP-C / cytochrome b-c1
complex subunit 7 / QCR7) is a small (~13.5 kDa, 111 aa) nuclear-encoded, non-catalytic
structural subunit of mitochondrial respiratory Complex III (the cytochrome b-c1 complex /
ubiquinol-cytochrome c oxidoreductase). It is one of the low-molecular-weight subunits of
the 11-subunit complex; the redox catalysis of Complex III is carried out by the catalytic
subunits cytochrome b, the Rieske iron-sulfur protein (UQCRFS1) and cytochrome c1, whereas
UQCRB contributes to assembly and structural integrity of the complex rather than to
catalysis. Complex III is an obligate dimer embedded as a peripheral protein on the matrix
side of the mitochondrial inner membrane, and it associates with Complex I and Complex IV to
form respiratory supercomplexes and megacomplexes. Within the electron transport chain,
Complex III transfers electrons from ubiquinol to cytochrome c, coupling this redox reaction
to proton translocation across the inner membrane (the Q cycle) and thereby contributing to
oxidative phosphorylation and aerobic respiration. UQCRB was originally proposed to be the
ubiquinone-binding protein, but this ubiquinone-binding role is no longer considered
established. Loss-of-function variants in UQCRB cause mitochondrial complex III deficiency
(nuclear type 3), a mitochondrial disorder that can present with hypoglycemia and lactic
acidosis.
alternative_products:
- name: '1'
id: P14927-1
- name: '2'
id: P14927-2
sequence_note: VSP_045601
existing_annotations:
- term:
id: GO:0045275
label: respiratory chain complex III
evidence_type: IBA
original_reference_id: GO_REF:0000033
qualifier: part_of
review:
summary: >-
Phylogenetic (IBA) annotation placing UQCRB as part of respiratory chain complex III.
This is the defining, well-established localization/membership of this subunit and is
supported by cryo-EM structures of human Complex III and by UniProt.
action: ACCEPT
reason: >-
UQCRB is a bona fide low-molecular-weight subunit of the cytochrome b-c1 complex
(Complex III). This is confirmed structurally and by the family definition, and the
complex membership is a core aspect of the gene's function.
supported_by:
- reference_id: file:human/UQCRB/UQCRB-uniprot.txt
supporting_text: "Component of the ubiquinol-cytochrome c oxidoreductase, a"
- term:
id: GO:0006122
label: mitochondrial electron transport, ubiquinol to cytochrome c
evidence_type: IBA
original_reference_id: GO_REF:0000033
qualifier: involved_in
review:
summary: >-
Phylogenetic (IBA) annotation to the specific Complex III process, transfer of
electrons from ubiquinol to cytochrome c. As a structural subunit of Complex III,
UQCRB participates in this process.
action: ACCEPT
reason: >-
This is the core biological process of Complex III and the most appropriate specific
BP term for a CIII subunit. Well supported by the complex's catalytic role.
supported_by:
- reference_id: file:human/UQCRB/UQCRB-uniprot.txt
supporting_text: "transfer from ubiquinol to cytochrome c, linking this redox reaction to"
- term:
id: GO:0005743
label: mitochondrial inner membrane
evidence_type: IEA
original_reference_id: GO_REF:0000044
qualifier: located_in
review:
summary: >-
Electronic annotation from UniProt Subcellular Location mapping placing UQCRB in the
mitochondrial inner membrane. Consistent with its role as a peripheral inner-membrane
Complex III subunit.
action: ACCEPT
reason: >-
Complex III, and hence UQCRB, resides in the mitochondrial inner membrane. This is the
correct, specific location and matches the UniProt subcellular location.
supported_by:
- reference_id: file:human/UQCRB/UQCRB-uniprot.txt
supporting_text: >-
SUBCELLULAR LOCATION: Mitochondrion inner membrane
- term:
id: GO:0006122
label: mitochondrial electron transport, ubiquinol to cytochrome c
evidence_type: IEA
original_reference_id: GO_REF:0000002
qualifier: involved_in
review:
summary: >-
InterPro2GO electronic annotation to the Complex III electron transport process, based
on the QCR7 family signatures (IPR003197, IPR036544). Duplicates the IBA/NAS annotations
to the same specific BP.
action: ACCEPT
reason: >-
The InterPro-to-GO mapping is appropriate for this family and points to the correct,
specific Complex III process. Consistent with the experimental and phylogenetic evidence.
supported_by:
- reference_id: file:human/UQCRB/UQCRB-uniprot.txt
supporting_text: "transfer from ubiquinol to cytochrome c, linking this redox reaction to"
- term:
id: GO:0016020
label: membrane
evidence_type: IEA
original_reference_id: GO_REF:0000117
qualifier: located_in
review:
summary: >-
Generic ARBA machine-learning electronic annotation to "membrane". This is correct but
far less informative than the specific mitochondrial inner membrane location that is
also annotated.
action: MARK_AS_OVER_ANNOTATED
reason: >-
"membrane" is a high-level parent of the specific and better-supported term
mitochondrial inner membrane (GO:0005743). It is not wrong, but it is uninformatively
general given more precise annotations exist.
supported_by:
- reference_id: file:human/UQCRB/UQCRB-uniprot.txt
supporting_text: >-
SUBCELLULAR LOCATION: Mitochondrion inner membrane
- term:
id: GO:0045275
label: respiratory chain complex III
evidence_type: IEA
original_reference_id: GO_REF:0000002
qualifier: part_of
review:
summary: >-
InterPro2GO electronic annotation for complex III membership based on the QCR7 family
superfamily signature (IPR036544). Duplicates the IBA and experimental (ComplexPortal
IPI) annotations to the same term.
action: ACCEPT
reason: >-
Correct complex membership for a QCR7-family protein; consistent with structural and
phylogenetic evidence.
supported_by:
- reference_id: file:human/UQCRB/UQCRB-uniprot.txt
supporting_text: "Component of the ubiquinol-cytochrome c oxidoreductase, a"
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:16189514
qualifier: enables
review:
summary: >-
Large-scale protein-protein interaction (IntAct/IPI) annotation to the uninformative
term "protein binding". From a high-throughput human interactome screen.
action: MARK_AS_OVER_ANNOTATED
reason: >-
"protein binding" (GO:0005515) is an uninformative molecular function term that does not
capture the actual, specific function of UQCRB. This is an experimental IntAct record,
so it is retained rather than removed, but flagged as over-annotated per curation policy
that discourages bare "protein binding".
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:25416956
qualifier: enables
review:
summary: >-
Large-scale interactome (HuRI / IPI) annotation to the uninformative term
"protein binding".
action: MARK_AS_OVER_ANNOTATED
reason: >-
Uninformative "protein binding" from a high-throughput interactome map. Retained as an
experimental IntAct record but flagged as over-annotated; it does not describe UQCRB's
specific structural function within Complex III.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:28514442
qualifier: enables
review:
summary: >-
Large-scale interactome (BioPlex / IPI) annotation to the uninformative term
"protein binding".
action: MARK_AS_OVER_ANNOTATED
reason: >-
Uninformative "protein binding" from a high-throughput interactome study. Retained as an
experimental IntAct record but flagged as over-annotated.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:32296183
qualifier: enables
review:
summary: >-
Large-scale binary interactome (HuRI reference map / IPI) annotation to the
uninformative term "protein binding".
action: MARK_AS_OVER_ANNOTATED
reason: >-
Uninformative "protein binding" from a high-throughput binary interactome map. Retained
as an experimental IntAct record but flagged as over-annotated.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:32814053
qualifier: enables
review:
summary: >-
Large-scale interactome (neurodegenerative-disease interactome / IPI) annotation to the
uninformative term "protein binding".
action: MARK_AS_OVER_ANNOTATED
reason: >-
Uninformative "protein binding" from a high-throughput interactome study. Retained as an
experimental IntAct record but flagged as over-annotated.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:33961781
qualifier: enables
review:
summary: >-
Large-scale interactome (BioPlex 3.0 dual-cell networks / IPI) annotation to the
uninformative term "protein binding".
action: MARK_AS_OVER_ANNOTATED
reason: >-
Uninformative "protein binding" from a high-throughput interactome study. Retained as an
experimental IntAct record but flagged as over-annotated.
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:40205054
qualifier: enables
review:
summary: >-
Large-scale multimodal cell-map interactome (IPI) annotation to the uninformative term
"protein binding".
action: MARK_AS_OVER_ANNOTATED
reason: >-
Uninformative "protein binding" from a high-throughput interactome/cell-map study.
Retained as an experimental IntAct record but flagged as over-annotated.
- term:
id: GO:0005743
label: mitochondrial inner membrane
evidence_type: ISS
original_reference_id: GO_REF:0000024
qualifier: located_in
review:
summary: >-
Curator-judged sequence-similarity (ISS) transfer of the mitochondrial inner membrane
location from the bovine ortholog (UniProtKB:P00128). Consistent with all other location
evidence.
action: ACCEPT
reason: >-
The inner-membrane localization is well established for Complex III subunits across
species; the ISS transfer from the bovine QCR7 ortholog is appropriate and matches the
specific, correct location.
supported_by:
- reference_id: file:human/UQCRB/UQCRB-uniprot.txt
supporting_text: >-
SUBCELLULAR LOCATION: Mitochondrion inner membrane
- term:
id: GO:0005743
label: mitochondrial inner membrane
evidence_type: IDA
original_reference_id: PMID:28844695
qualifier: located_in
review:
summary: >-
Direct experimental (IDA, ComplexPortal) assignment of UQCRB to the mitochondrial inner
membrane, based on the cryo-EM structure of the human respiratory megacomplex in which
Complex III is resolved in the inner membrane.
action: ACCEPT
reason: >-
Strong experimental support: the cryo-EM structure of the human MCI2III2IV2 megacomplex
places the dimeric Complex III (and thus its UQCRB subunit) in the mitochondrial inner
membrane. This is the core, specific location.
supported_by:
- reference_id: PMID:28844695
supporting_text: >-
The MCI2III2IV2 forms a circular structure with the dimeric CIII located in the
center, where it is surrounded by two copies each of CI and CIV.
- term:
id: GO:0006122
label: mitochondrial electron transport, ubiquinol to cytochrome c
evidence_type: NAS
original_reference_id: PMID:28844695
qualifier: involved_in
review:
summary: >-
Non-traceable author statement (NAS, ComplexPortal) that UQCRB, as a Complex III subunit,
is involved in mitochondrial electron transport from ubiquinol to cytochrome c.
action: ACCEPT
reason: >-
This is the core, specific process of Complex III and is consistent with the
IBA/InterPro annotations to the same term and with the structural characterization of
the electron transport chain in this study.
supported_by:
- reference_id: PMID:28844695
supporting_text: >-
Two cytochrome c (Cyt.c) molecules are positioned to accept electrons on the surface
of the c1 state CIII dimer.
- term:
id: GO:0045275
label: respiratory chain complex III
evidence_type: IPI
original_reference_id: PMID:28844695
qualifier: part_of
review:
summary: >-
Experimental (IPI, ComplexPortal) assignment of UQCRB as part of respiratory chain
complex III, based on the cryo-EM structure that resolves the individual subunits of
human Complex III.
action: ACCEPT
reason: >-
Direct structural evidence for UQCRB being a component of Complex III. Core complex
membership annotation.
supported_by:
- reference_id: PMID:28844695
supporting_text: >-
The structure not only reveals the precise assignment of individual subunits of human
CI and CIII
- term:
id: GO:0045333
label: cellular respiration
evidence_type: NAS
original_reference_id: PMID:28844695
qualifier: involved_in
review:
summary: >-
Non-traceable author statement (NAS, ComplexPortal) annotating UQCRB to the broad process
"cellular respiration".
action: KEEP_AS_NON_CORE
reason: >-
Correct but general: cellular respiration is a broad parent process. The more specific
and informative BP is mitochondrial electron transport, ubiquinol to cytochrome c
(GO:0006122), which is separately annotated and represents the core function. Retained
as valid but non-core.
supported_by:
- reference_id: file:human/UQCRB/UQCRB-uniprot.txt
supporting_text: "electron transport chain which drives oxidative phosphorylation"
- term:
id: GO:0005739
label: mitochondrion
evidence_type: HTP
original_reference_id: PMID:34800366
qualifier: located_in
review:
summary: >-
High-throughput (HTP) proteomic identification of UQCRB in the mitochondrion, from a
quantitative high-confidence human mitochondrial proteome (MitoCoP). Correct but less
specific than the mitochondrial inner membrane location.
action: ACCEPT
reason: >-
Reliable high-throughput evidence for mitochondrial localization. It is a general parent
of the more specific inner-membrane location, but it is correct and independently
corroborates the organellar assignment.
supported_by:
- reference_id: PMID:34800366
supporting_text: mitochondrial high-confidence proteome of >1,100 proteins (MitoCoP)
- term:
id: GO:0005743
label: mitochondrial inner membrane
evidence_type: TAS
original_reference_id: Reactome:R-HSA-164651
qualifier: located_in
review:
summary: >-
Traceable author statement (Reactome) placing UQCRB in the mitochondrial inner membrane,
associated with the reaction "Electron transfer from ubiquinol to cytochrome c of complex
III".
action: ACCEPT
reason: >-
Correct, specific location consistent with all other evidence. Reactome pathway context
matches the Complex III role.
supported_by:
- reference_id: Reactome:R-HSA-164651
supporting_text: >-
The protonmotive Q cycle is the mechanism by which complex III transfers electrons
from ubiquinol to cytochrome c, linking this process to translocation of protons across
the membrane.
- term:
id: GO:0005743
label: mitochondrial inner membrane
evidence_type: TAS
original_reference_id: Reactome:R-HSA-9906017
qualifier: located_in
review:
summary: >-
Traceable author statement (Reactome) placing UQCRB in the mitochondrial inner membrane,
in the context of Complex III assembly (proteolytic processing of the UQCRFS1 subunit).
action: ACCEPT
reason: >-
Correct, specific location. The Reactome reaction concerns Complex III assembly in the
inner membrane, consistent with UQCRB's structural/assembly role.
supported_by:
- reference_id: Reactome:R-HSA-9906017
supporting_text: >-
Proteolytic processing is necessary for the correct insertion of UQCRFS1 in the complex
III dimer.
- term:
id: GO:0005743
label: mitochondrial inner membrane
evidence_type: TAS
original_reference_id: Reactome:R-HSA-9906042
qualifier: located_in
review:
summary: >-
Traceable author statement (Reactome) placing UQCRB in the mitochondrial inner membrane,
in the context of Complex III maturation (TTC19 clearance of UQCRFS1 fragments).
action: ACCEPT
reason: >-
Correct, specific location consistent with the Complex III assembly/maturation pathway
context.
supported_by:
- reference_id: Reactome:R-HSA-9906042
supporting_text: >-
N-terminal cleavage fragments of UQCRFS1 are cleared by TTC19, stabilizing the final
complex.
- term:
id: GO:0006119
label: oxidative phosphorylation
evidence_type: TAS
original_reference_id: PMID:3056408
qualifier: involved_in
review:
summary: >-
Traceable author statement (from the original human QP-C/UQCRB cDNA cloning paper)
annotating involvement in oxidative phosphorylation, reflecting Complex III's role in
driving OXPHOS via the electron transport chain.
action: ACCEPT
reason: >-
Complex III is a core component of the electron transport chain that drives oxidative
phosphorylation, so this is a valid process annotation for UQCRB. It is broader than the
specific electron-transport step (GO:0006122) but correctly captures the downstream
energetic role.
supported_by:
- reference_id: file:human/UQCRB/UQCRB-uniprot.txt
supporting_text: "electron transport chain which drives oxidative phosphorylation"
- term:
id: GO:0009060
label: aerobic respiration
evidence_type: TAS
original_reference_id: PMID:3056408
qualifier: involved_in
review:
summary: >-
Traceable author statement (original QP-C cDNA cloning paper) annotating involvement in
aerobic respiration.
action: KEEP_AS_NON_CORE
reason: >-
Correct but broad. Aerobic respiration is a high-level process; the core, specific
function is captured by mitochondrial electron transport, ubiquinol to cytochrome c
(GO:0006122). Retained as valid but non-core.
supported_by:
- reference_id: PMID:3056408
supporting_text: >-
The ubiquinone-binding protein (QP-C) is a nuclear-encoded component of
ubiquinol-cytochrome c oxidoreductase in the mitochondrial respiratory chain and plays
an important role in electron transfer
- term:
id: GO:0098803
label: respiratory chain complex
evidence_type: TAS
original_reference_id: PMID:3056408
qualifier: located_in
review:
summary: >-
Traceable author statement placing UQCRB in a respiratory chain complex, based on the
original cDNA cloning paper identifying QP-C as a component of ubiquinol-cytochrome c
oxidoreductase.
action: MARK_AS_OVER_ANNOTATED
reason: >-
Correct but general: respiratory chain complex (GO:0098803) is a parent of the specific
and better-supported term respiratory chain complex III (GO:0045275), which is annotated
by IBA, InterPro and experimental (ComplexPortal IPI) evidence. Retained but flagged as
over-general.
supported_by:
- reference_id: PMID:3056408
supporting_text: >-
The ubiquinone-binding protein (QP-C) is a nuclear-encoded component of
ubiquinol-cytochrome c oxidoreductase in the mitochondrial respiratory chain
- term:
id: GO:0005198
label: structural molecule activity
evidence_type: ISS
original_reference_id: file:human/UQCRB/UQCRB-uniprot.txt
qualifier: enables
review:
summary: >-
Proposed molecular function annotation. UQCRB has no informative molecular function in
GOA (only the uninformative "protein binding" IPIs). As a non-catalytic subunit of
Complex III, its molecular function is best captured as structural molecule activity,
contributing to the structural integrity of the cytochrome b-c1 complex.
action: NEW
reason: >-
The catalytic activity of Complex III (electron transfer from ubiquinol to cytochrome c)
is carried by cytochrome b, the Rieske iron-sulfur protein and cytochrome c1; UQCRB is a
low-molecular-weight, non-catalytic structural subunit. Structural molecule activity
(GO:0005198) is the appropriate subunit-specific molecular function, and it is not
currently represented in GOA. No catalytic activity is asserted for UQCRB.
supported_by:
- reference_id: file:human/UQCRB/UQCRB-uniprot.txt
supporting_text: "Component of the ubiquinol-cytochrome c oxidoreductase, a"
core_functions:
- description: >-
Non-catalytic structural subunit of mitochondrial respiratory Complex III (cytochrome
b-c1 complex / ubiquinol-cytochrome c oxidoreductase). UQCRB contributes to the structural
integrity and assembly of the complex; the complex as a whole transfers electrons from
ubiquinol to cytochrome c in the mitochondrial inner membrane during aerobic respiration
and oxidative phosphorylation.
molecular_function:
id: GO:0005198
label: structural molecule activity
contributes_to_molecular_function:
id: GO:0008121
label: quinol-cytochrome-c reductase activity
directly_involved_in:
- id: GO:0006122
label: mitochondrial electron transport, ubiquinol to cytochrome c
locations:
- id: GO:0005743
label: mitochondrial inner membrane
in_complex:
id: GO:0045275
label: respiratory chain complex III
supported_by:
- reference_id: file:human/UQCRB/UQCRB-uniprot.txt
supporting_text: "Component of the ubiquinol-cytochrome c oxidoreductase, a"
- reference_id: PMID:28844695
supporting_text: >-
The structure not only reveals the precise assignment of individual subunits of human CI
and CIII
references:
- id: GO_REF:0000002
title: Gene Ontology annotation through association of InterPro records with GO
terms
findings: []
- id: GO_REF:0000024
title: Manual transfer of experimentally-verified manual GO annotation data to orthologs
by curator judgment of sequence similarity
findings: []
- id: GO_REF:0000033
title: Annotation inferences using phylogenetic trees
findings: []
- id: GO_REF:0000044
title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location
vocabulary mapping, accompanied by conservative changes to GO terms applied by
UniProt
findings: []
- id: GO_REF:0000117
title: Electronic Gene Ontology annotations created by ARBA machine learning models
findings: []
- id: PMID:16189514
title: Towards a proteome-scale map of the human protein-protein interaction network.
findings: []
reference_review:
relevance: LOW
correctness: VERIFIED
review_notes: >-
High-throughput interactome screen; source of a bare "protein binding" IPI. Does not
inform UQCRB's specific function.
- id: PMID:25416956
title: A proteome-scale map of the human interactome network.
findings: []
reference_review:
relevance: LOW
correctness: VERIFIED
review_notes: >-
Large-scale interactome map; source of a bare "protein binding" IPI. Contextual only.
- id: PMID:28514442
title: Architecture of the human interactome defines protein communities and disease
networks.
findings: []
reference_review:
relevance: LOW
correctness: VERIFIED
review_notes: >-
BioPlex interactome; source of a bare "protein binding" IPI. Contextual only.
- id: PMID:28844695
title: Architecture of Human Mitochondrial Respiratory Megacomplex I(2)III(2)IV(2).
findings: []
reference_review:
relevance: HIGH
correctness: VERIFIED
review_notes: >-
Cryo-EM structure of the human respiratory megacomplex; directly resolves Complex III
(including UQCRB) in the inner membrane and its role in electron transfer to cytochrome c.
- id: PMID:3056408
title: Cloning and sequencing of a cDNA for human mitochondrial ubiquinone-binding
protein of complex III.
findings: []
reference_review:
relevance: HIGH
correctness: VERIFIED
review_notes: >-
Original cloning of human UQCRB/QP-C cDNA; establishes it as a nuclear-encoded component
of ubiquinol-cytochrome c oxidoreductase (Complex III). Note the historical
"ubiquinone-binding protein" attribution is now flagged CAUTION by UniProt.
- id: PMID:32296183
title: A reference map of the human binary protein interactome.
findings: []
reference_review:
relevance: LOW
correctness: VERIFIED
review_notes: >-
HuRI binary interactome; source of bare "protein binding" IPIs. Contextual only.
- id: PMID:32814053
title: Interactome Mapping Provides a Network of Neurodegenerative Disease Proteins
and Uncovers Widespread Protein Aggregation in Affected Brains.
findings: []
reference_review:
relevance: LOW
correctness: VERIFIED
review_notes: >-
Neurodegenerative-disease interactome; source of bare "protein binding" IPIs. Contextual
only.
- id: PMID:33961781
title: Dual proteome-scale networks reveal cell-specific remodeling of the human
interactome.
findings: []
reference_review:
relevance: LOW
correctness: VERIFIED
review_notes: >-
BioPlex 3.0 interactome; source of bare "protein binding" IPIs. Contextual only.
- id: PMID:34800366
title: Quantitative high-confidence human mitochondrial proteome and its dynamics
in cellular context.
findings: []
reference_review:
relevance: MEDIUM
correctness: VERIFIED
review_notes: >-
MitoCoP high-confidence mitochondrial proteome; independently supports mitochondrial
localization of UQCRB.
- id: PMID:40205054
title: Multimodal cell maps as a foundation for structural and functional genomics.
findings: []
reference_review:
relevance: LOW
correctness: VERIFIED
review_notes: >-
Multimodal cell-map interactome; source of a bare "protein binding" IPI. Contextual only.
- id: Reactome:R-HSA-164651
title: Electron transfer from ubiquinol to cytochrome c of complex III
findings: []
- id: Reactome:R-HSA-9906017
title: Unknown peptidase cleaves UQCRFS1 subunit
findings: []
- id: Reactome:R-HSA-9906042
title: TTC19 clears UQCRFS1 fragments from Complex III
findings: []
- id: file:human/UQCRB/UQCRB-uniprot.txt
title: UniProtKB P14927 (QCR7_HUMAN) Cytochrome b-c1 complex subunit 7
findings: []