Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0005829 cytosol	IBA GO_REF:0000033	ACCEPT	Summary: cytosol localization is supported for a smaller PRDX4 pool, including the cytoplasmic fraction implicated in NF-kappaB redox modulation. Reason: Although the endoplasmic reticulum is the dominant core location, UniProt and experimental literature support a cytoplasmic fraction. The term is therefore valid, with ER retained as the primary localization. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm. Endoplasmic reticulum. Note=A small fraction of the protein is cytoplasmic. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report emphasizes ER localization as primary while noting additional cytosolic or secreted/extracellular PRDX4 contexts.
GO:0006979 response to oxidative stress	IBA GO_REF:0000033	ACCEPT	Summary: response to oxidative stress is supported by PRDX4 peroxide-reducing activity and its role in cellular redox protection. Reason: PRDX4 directly detoxifies hydroperoxides through the thioredoxin system, so these redox and peroxide catabolic process annotations are appropriate biological-process summaries. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt Plays a role in cell protection against oxidative stress by detoxifying peroxides and as sensor of hydrogen peroxide-mediated signaling events. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and other hydroperoxides and supports ER redox/proteostasis biology.
GO:0008379 thioredoxin peroxidase activity	IBA GO_REF:0000033	ACCEPT	Summary: thioredoxin peroxidase activity accurately captures PRDX4 catalysis as a thioredoxin-dependent 2-Cys peroxiredoxin that reduces hydroperoxides. Reason: This is the core molecular function of PRDX4 and is supported by both the original thioredoxin peroxidase study and structural/catalytic analysis. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt Reaction=a hydroperoxide + [thioredoxin]-dithiol = an alcohol + [thioredoxin]-disulfide + H2O; EC=1.11.1.24. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and other hydroperoxides and supports ER redox/proteostasis biology.
GO:0042744 hydrogen peroxide catabolic process	IBA GO_REF:0000033	ACCEPT	Summary: hydrogen peroxide catabolic process is supported by PRDX4 peroxide-reducing activity and its role in cellular redox protection. Reason: PRDX4 directly detoxifies hydroperoxides through the thioredoxin system, so these redox and peroxide catabolic process annotations are appropriate biological-process summaries. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt Plays a role in cell protection against oxidative stress by detoxifying peroxides and as sensor of hydrogen peroxide-mediated signaling events. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and other hydroperoxides and supports ER redox/proteostasis biology.
GO:0045454 cell redox homeostasis	IBA GO_REF:0000033	ACCEPT	Summary: cell redox homeostasis is supported by PRDX4 peroxide-reducing activity and its role in cellular redox protection. Reason: PRDX4 directly detoxifies hydroperoxides through the thioredoxin system, so these redox and peroxide catabolic process annotations are appropriate biological-process summaries. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt Plays a role in cell protection against oxidative stress by detoxifying peroxides and as sensor of hydrogen peroxide-mediated signaling events. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and other hydroperoxides and supports ER redox/proteostasis biology.
GO:0005783 endoplasmic reticulum	IBA GO_REF:0000033	ACCEPT	Summary: Endoplasmic reticulum localization is a core location for PRDX4. UniProt states that PRDX4 is cotranslationally translocated to and retained within the ER. Reason: This is the most informative cellular component for PRDX4 and matches the enzyme biology as the ER-localized peroxiredoxin. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm. Endoplasmic reticulum. Note=Cotranslationally translocated to and retained within the endoplasmic reticulum. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report summarizes PRDX4 as localized mainly to the endoplasmic reticulum, with ER luminal targeting and retention through oxidoreductase/chaperone interactions.
GO:0098869 cellular oxidant detoxification	IEA GO_REF:0000120	ACCEPT	Summary: cellular oxidant detoxification is supported by PRDX4 peroxide-reducing activity and its role in cellular redox protection. Reason: PRDX4 directly detoxifies hydroperoxides through the thioredoxin system, so these redox and peroxide catabolic process annotations are appropriate biological-process summaries. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt Plays a role in cell protection against oxidative stress by detoxifying peroxides and as sensor of hydrogen peroxide-mediated signaling events. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and other hydroperoxides and supports ER redox/proteostasis biology.
GO:0004601 peroxidase activity	IEA GO_REF:0000043	MARK AS OVER ANNOTATED	Summary: peroxidase activity is compatible with PRDX4 biology but is a broad parent or less-informative activity compared with the specific thioredoxin-dependent peroxiredoxin annotations already present. Reason: The precise MF terms GO:0140824/GO:0051920/GO:0008379 better represent PRDX4. Broad antioxidant/peroxidase/oxidoreductase terms add little specificity. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt PRDX4 is annotated as a thiol-specific peroxidase that reduces hydrogen peroxide and organic hydroperoxides.
GO:0005737 cytoplasm	IEA GO_REF:0000120	ACCEPT	Summary: cytoplasm localization is supported for a smaller PRDX4 pool, including the cytoplasmic fraction implicated in NF-kappaB redox modulation. Reason: Although the endoplasmic reticulum is the dominant core location, UniProt and experimental literature support a cytoplasmic fraction. The term is therefore valid, with ER retained as the primary localization. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm. Endoplasmic reticulum. Note=A small fraction of the protein is cytoplasmic. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report emphasizes ER localization as primary while noting additional cytosolic or secreted/extracellular PRDX4 contexts.
GO:0005783 endoplasmic reticulum	IEA GO_REF:0000120	ACCEPT	Summary: Endoplasmic reticulum localization is a core location for PRDX4. UniProt states that PRDX4 is cotranslationally translocated to and retained within the ER. Reason: This is the most informative cellular component for PRDX4 and matches the enzyme biology as the ER-localized peroxiredoxin. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm. Endoplasmic reticulum. Note=Cotranslationally translocated to and retained within the endoplasmic reticulum. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report summarizes PRDX4 as localized mainly to the endoplasmic reticulum, with ER luminal targeting and retention through oxidoreductase/chaperone interactions.
GO:0016209 antioxidant activity	IEA GO_REF:0000120	MARK AS OVER ANNOTATED	Summary: antioxidant activity is compatible with PRDX4 biology but is a broad parent or less-informative activity compared with the specific thioredoxin-dependent peroxiredoxin annotations already present. Reason: The precise MF terms GO:0140824/GO:0051920/GO:0008379 better represent PRDX4. Broad antioxidant/peroxidase/oxidoreductase terms add little specificity. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt PRDX4 is annotated as a thiol-specific peroxidase that reduces hydrogen peroxide and organic hydroperoxides.
GO:0016491 oxidoreductase activity	IEA GO_REF:0000120	MARK AS OVER ANNOTATED	Summary: oxidoreductase activity is compatible with PRDX4 biology but is a broad parent or less-informative activity compared with the specific thioredoxin-dependent peroxiredoxin annotations already present. Reason: The precise MF terms GO:0140824/GO:0051920/GO:0008379 better represent PRDX4. Broad antioxidant/peroxidase/oxidoreductase terms add little specificity. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt PRDX4 is annotated as a thiol-specific peroxidase that reduces hydrogen peroxide and organic hydroperoxides.
GO:0051920 peroxiredoxin activity	IEA GO_REF:0000002	ACCEPT	Summary: peroxiredoxin activity accurately captures PRDX4 catalysis as a thioredoxin-dependent 2-Cys peroxiredoxin that reduces hydroperoxides. Reason: This is the core molecular function of PRDX4 and is supported by both the original thioredoxin peroxidase study and structural/catalytic analysis. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt Reaction=a hydroperoxide + [thioredoxin]-dithiol = an alcohol + [thioredoxin]-disulfide + H2O; EC=1.11.1.24. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and other hydroperoxides and supports ER redox/proteostasis biology.
GO:0140824 thioredoxin-dependent peroxiredoxin activity	IEA GO_REF:0000120	ACCEPT	Summary: thioredoxin-dependent peroxiredoxin activity accurately captures PRDX4 catalysis as a thioredoxin-dependent 2-Cys peroxiredoxin that reduces hydroperoxides. Reason: This is the core molecular function of PRDX4 and is supported by both the original thioredoxin peroxidase study and structural/catalytic analysis. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt Reaction=a hydroperoxide + [thioredoxin]-dithiol = an alcohol + [thioredoxin]-disulfide + H2O; EC=1.11.1.24. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and other hydroperoxides and supports ER redox/proteostasis biology.
GO:0005515 protein binding	IPI PMID:17644091 Peroxiredoxin-4 interacts with and regulates the thromboxane...	MARK AS OVER ANNOTATED	Summary: Generic protein binding from interactome evidence does not describe the specific PRDX4 molecular function. Reason: PRDX4 has biologically relevant partners and oligomerization, but GO:0005515 is too vague. Specific terms for peroxiredoxin activity and identical protein binding capture the supported function better. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt The curated function describes thioredoxin-dependent peroxidase activity; interaction rows are partner lists rather than specific functional annotations.
GO:0005515 protein binding	IPI PMID:21057456 Recycling of peroxiredoxin IV provides a novel pathway for d...	MARK AS OVER ANNOTATED	Summary: Generic protein binding from interactome evidence does not describe the specific PRDX4 molecular function. Reason: PRDX4 has biologically relevant partners and oligomerization, but GO:0005515 is too vague. Specific terms for peroxiredoxin activity and identical protein binding capture the supported function better. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt The curated function describes thioredoxin-dependent peroxidase activity; interaction rows are partner lists rather than specific functional annotations.
GO:0005515 protein binding	IPI PMID:21988832 Toward an understanding of the protein interaction network o...	MARK AS OVER ANNOTATED	Summary: Generic protein binding from interactome evidence does not describe the specific PRDX4 molecular function. Reason: PRDX4 has biologically relevant partners and oligomerization, but GO:0005515 is too vague. Specific terms for peroxiredoxin activity and identical protein binding capture the supported function better. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt The curated function describes thioredoxin-dependent peroxidase activity; interaction rows are partner lists rather than specific functional annotations.
GO:0005515 protein binding	IPI PMID:25959826 Quantitative interaction proteomics of neurodegenerative dis...	MARK AS OVER ANNOTATED	Summary: Generic protein binding from interactome evidence does not describe the specific PRDX4 molecular function. Reason: PRDX4 has biologically relevant partners and oligomerization, but GO:0005515 is too vague. Specific terms for peroxiredoxin activity and identical protein binding capture the supported function better. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt The curated function describes thioredoxin-dependent peroxidase activity; interaction rows are partner lists rather than specific functional annotations.
GO:0005515 protein binding	IPI PMID:32814053 Interactome Mapping Provides a Network of Neurodegenerative ...	MARK AS OVER ANNOTATED	Summary: Generic protein binding from interactome evidence does not describe the specific PRDX4 molecular function. Reason: PRDX4 has biologically relevant partners and oligomerization, but GO:0005515 is too vague. Specific terms for peroxiredoxin activity and identical protein binding capture the supported function better. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt The curated function describes thioredoxin-dependent peroxidase activity; interaction rows are partner lists rather than specific functional annotations.
GO:0005515 protein binding	IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling...	MARK AS OVER ANNOTATED	Summary: Generic protein binding from interactome evidence does not describe the specific PRDX4 molecular function. Reason: PRDX4 has biologically relevant partners and oligomerization, but GO:0005515 is too vague. Specific terms for peroxiredoxin activity and identical protein binding capture the supported function better. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt The curated function describes thioredoxin-dependent peroxidase activity; interaction rows are partner lists rather than specific functional annotations.
GO:0005829 cytosol	IEA GO_REF:0000107	ACCEPT	Summary: cytosol localization is supported for a smaller PRDX4 pool, including the cytoplasmic fraction implicated in NF-kappaB redox modulation. Reason: Although the endoplasmic reticulum is the dominant core location, UniProt and experimental literature support a cytoplasmic fraction. The term is therefore valid, with ER retained as the primary localization. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm. Endoplasmic reticulum. Note=A small fraction of the protein is cytoplasmic. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report emphasizes ER localization as primary while noting additional cytosolic or secreted/extracellular PRDX4 contexts.
GO:0042802 identical protein binding	IEA GO_REF:0000107	ACCEPT	Summary: Identical protein binding is supported by PRDX4 homodimerization and decamer formation, which are part of its 2-Cys peroxiredoxin catalytic assembly. Reason: Unlike generic protein binding, identical protein binding is mechanistically informative for PRDX4 because catalysis uses a dimeric interface and oxidized PRDX4 forms disulfide-linked homodimers/decamers. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt SUBUNIT: Homodimer; disulfide-linked, upon oxidation. 5 homodimers assemble to form a ring-like decamer.
GO:0005783 endoplasmic reticulum	IDA GO_REF:0000052	ACCEPT	Summary: Endoplasmic reticulum localization is a core location for PRDX4. UniProt states that PRDX4 is cotranslationally translocated to and retained within the ER. Reason: This is the most informative cellular component for PRDX4 and matches the enzyme biology as the ER-localized peroxiredoxin. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm. Endoplasmic reticulum. Note=Cotranslationally translocated to and retained within the endoplasmic reticulum. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report summarizes PRDX4 as localized mainly to the endoplasmic reticulum, with ER luminal targeting and retention through oxidoreductase/chaperone interactions.
GO:0005829 cytosol	IDA GO_REF:0000052	ACCEPT	Summary: cytosol localization is supported for a smaller PRDX4 pool, including the cytoplasmic fraction implicated in NF-kappaB redox modulation. Reason: Although the endoplasmic reticulum is the dominant core location, UniProt and experimental literature support a cytoplasmic fraction. The term is therefore valid, with ER retained as the primary localization. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt SUBCELLULAR LOCATION: Cytoplasm. Endoplasmic reticulum. Note=A small fraction of the protein is cytoplasmic. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report emphasizes ER localization as primary while noting additional cytosolic or secreted/extracellular PRDX4 contexts.
GO:0060090 molecular adaptor activity	EXP PMID:21916849 Structural insights into the peroxidase activity and inactiv...	MODIFY	Summary: The cited structural study supports PRDX4 peroxidase catalysis, oligomerization, and overoxidation sensitivity, but it does not establish molecular adaptor activity as a distinct molecular function. Reason: The biological evidence should be captured with a catalytic peroxiredoxin term rather than adaptor or sequestering activity. The best replacement is the specific thioredoxin-dependent peroxiredoxin activity term already supported by the same catalytic mechanism. Proposed replacements: thioredoxin-dependent peroxiredoxin activity Supporting Evidence: PMID:21916849 Prx4 exhibits a toroid-shaped decamer constructed of five catalytic dimers.
GO:0140313 molecular sequestering activity	IDA PMID:21916849 Structural insights into the peroxidase activity and inactiv...	MODIFY	Summary: The cited structural study supports PRDX4 peroxidase catalysis, oligomerization, and overoxidation sensitivity, but it does not establish molecular sequestering activity as a distinct molecular function. Reason: The biological evidence should be captured with a catalytic peroxiredoxin term rather than adaptor or sequestering activity. The best replacement is the specific thioredoxin-dependent peroxiredoxin activity term already supported by the same catalytic mechanism. Proposed replacements: thioredoxin-dependent peroxiredoxin activity Supporting Evidence: PMID:21916849 Prx4 exhibits a toroid-shaped decamer constructed of five catalytic dimers.
GO:0005576 extracellular region	TAS Reactome:R-HSA-6798748	KEEP AS NON CORE	Summary: extracellular region reflects secretory or extracellular detection/pathway context for PRDX4 rather than the main site of its curated peroxidase function. Reason: PRDX4 is an ER/secretory-pathway peroxiredoxin, so extracellular or granule-lumen pathway placements can be retained as non-core context while ER remains the primary location. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt PRDX4 is cotranslationally translocated to and retained within the endoplasmic reticulum. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report notes PRDX4 can be secreted/extracellular and has been detected in extracellular vesicle datasets, supporting non-core secretory/extracellular context.
GO:0005576 extracellular region	TAS Reactome:R-HSA-6800434	KEEP AS NON CORE	Summary: extracellular region reflects secretory or extracellular detection/pathway context for PRDX4 rather than the main site of its curated peroxidase function. Reason: PRDX4 is an ER/secretory-pathway peroxiredoxin, so extracellular or granule-lumen pathway placements can be retained as non-core context while ER remains the primary location. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt PRDX4 is cotranslationally translocated to and retained within the endoplasmic reticulum. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report notes PRDX4 can be secreted/extracellular and has been detected in extracellular vesicle datasets, supporting non-core secretory/extracellular context.
GO:0034774 secretory granule lumen	TAS Reactome:R-HSA-6798748	KEEP AS NON CORE	Summary: secretory granule lumen reflects secretory or extracellular detection/pathway context for PRDX4 rather than the main site of its curated peroxidase function. Reason: PRDX4 is an ER/secretory-pathway peroxiredoxin, so extracellular or granule-lumen pathway placements can be retained as non-core context while ER remains the primary location. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt PRDX4 is cotranslationally translocated to and retained within the endoplasmic reticulum. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report notes PRDX4 can be secreted/extracellular and has been detected in extracellular vesicle datasets, supporting non-core secretory/extracellular context.
GO:1904813 ficolin-1-rich granule lumen	TAS Reactome:R-HSA-6800434	KEEP AS NON CORE	Summary: ficolin-1-rich granule lumen reflects secretory or extracellular detection/pathway context for PRDX4 rather than the main site of its curated peroxidase function. Reason: PRDX4 is an ER/secretory-pathway peroxiredoxin, so extracellular or granule-lumen pathway placements can be retained as non-core context while ER remains the primary location. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt PRDX4 is cotranslationally translocated to and retained within the endoplasmic reticulum. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report notes PRDX4 can be secreted/extracellular and has been detected in extracellular vesicle datasets, supporting non-core secretory/extracellular context.
GO:0005634 nucleus	HDA PMID:21630459 Proteomic characterization of the human sperm nucleus.	KEEP AS NON CORE	Summary: nucleus comes from high-throughput proteomic detection and is not the main functional location of PRDX4. Reason: Retain the observation as non-core because proteomic localization can reflect cargo or context-specific detection. It should not displace the ER/cytoplasmic peroxiredoxin localization. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt The curated subcellular location is cytoplasm and endoplasmic reticulum, with ER retention noted as the main localization.
GO:0070062 extracellular exosome	HDA PMID:19199708 Proteomic analysis of human parotid gland exosomes by multid...	KEEP AS NON CORE	Summary: extracellular exosome comes from high-throughput proteomic detection and is not the main functional location of PRDX4. Reason: Retain the observation as non-core because proteomic localization can reflect cargo or context-specific detection. It should not displace the ER/cytoplasmic peroxiredoxin localization. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt The curated subcellular location is cytoplasm and endoplasmic reticulum, with ER retention noted as the main localization. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report notes PRDX4 can be secreted/extracellular and has been detected in extracellular vesicle datasets, supporting non-core secretory/extracellular context.
GO:0007252 I-kappaB phosphorylation	TAS PMID:9388242 Regulatory role for a novel human thioredoxin peroxidase in ...	MODIFY	Summary: PRDX4 modulates I-kappaB-alpha phosphorylation through redox regulation but is not the kinase that phosphorylates I-kappaB. Reason: The evidence supports regulation of I-kappaB phosphorylation, not execution of phosphorylation. The annotation should be moved to a regulatory BP term. Proposed replacements: regulation of I-kappaB phosphorylation Supporting Evidence: PMID:9388242 AOE372 defines a redox pathway that specifically regulates NF-kappaB activity via a modulation of IkappaB-alpha phosphorylation in the cytoplasm.
GO:0008379 thioredoxin peroxidase activity	TAS PMID:9388242 Regulatory role for a novel human thioredoxin peroxidase in ...	ACCEPT	Summary: thioredoxin peroxidase activity accurately captures PRDX4 catalysis as a thioredoxin-dependent 2-Cys peroxiredoxin that reduces hydroperoxides. Reason: This is the core molecular function of PRDX4 and is supported by both the original thioredoxin peroxidase study and structural/catalytic analysis. Supporting Evidence: file:human/PRDX4/PRDX4-uniprot.txt Reaction=a hydroperoxide + [thioredoxin]-dithiol = an alcohol + [thioredoxin]-disulfide + H2O; EC=1.11.1.24. file:human/PRDX4/PRDX4-deep-research-falcon.md Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and other hydroperoxides and supports ER redox/proteostasis biology.

Core Functions

Reduces hydrogen peroxide and organic hydroperoxides using thioredoxin, supporting peroxide detoxification and redox homeostasis primarily in the endoplasmic reticulum with a smaller cytoplasmic pool.

Molecular Function:

thioredoxin-dependent peroxiredoxin activity

Directly Involved In:

hydrogen peroxide catabolic process cell redox homeostasis

Cellular Locations:

endoplasmic reticulum cytosol

Substrates:

hydroperoxide

Supporting Evidence:

file:human/PRDX4/PRDX4-uniprot.txt
Thiol-specific peroxidase that catalyzes the reduction of hydrogen peroxide and organic hydroperoxides to water and alcohols, respectively.
file:human/PRDX4/PRDX4-deep-research-falcon.md
Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and organic hydroperoxides and functions mainly in the ER lumen.

References

GO_REF:0000002

Gene Ontology annotation through association of InterPro records with GO terms

GO_REF:0000033

Annotation inferences using phylogenetic trees

GO_REF:0000043

Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping

GO_REF:0000052

Gene Ontology annotation based on curation of immunofluorescence data

GO_REF:0000107

Automatic transfer of experimentally verified manual GO annotation data to orthologs using Ensembl Compara

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

PMID:17644091

Peroxiredoxin-4 interacts with and regulates the thromboxane A(2) receptor.

PMID:19199708

Proteomic analysis of human parotid gland exosomes by multidimensional protein identification technology (MudPIT).

PMID:21057456

Recycling of peroxiredoxin IV provides a novel pathway for disulphide formation in the endoplasmic reticulum.

PMID:21630459

Proteomic characterization of the human sperm nucleus.

PMID:21916849

Structural insights into the peroxidase activity and inactivation of human peroxiredoxin 4.

PMID:21988832

Toward an understanding of the protein interaction network of the human liver.

PMID:25959826

Quantitative interaction proteomics of neurodegenerative disease proteins.

PMID:32814053

Interactome Mapping Provides a Network of Neurodegenerative Disease Proteins and Uncovers Widespread Protein Aggregation in Affected Brains.

PMID:33961781

Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.

PMID:9388242

Regulatory role for a novel human thioredoxin peroxidase in NF-kappaB activation.

Reactome:R-HSA-6798748

Exocytosis of secretory granule lumen proteins

Reactome:R-HSA-6800434

Exocytosis of ficolin-rich granule lumen proteins

file:human/PRDX4/PRDX4-uniprot.txt

UniProt record for human PRDX4

file:human/PRDX4/PRDX4-deep-research-falcon.md

Falcon deep research on PRDX4 function

Falcon report identifies PRDX4 as ER-localized typical 2-Cys peroxiredoxin.

"PRDX4 catalyzes peroxide reduction through the canonical typical 2-Cys cycle"
Falcon report emphasizes ER luminal localization and secreted/extracellular context.

"PRDX4 is localized mainly to the endoplasmic reticulum"

Suggested Experiments

Experiment: Measure ER and cytosolic peroxide handling after PRDX4 knockout and compartment-targeted rescue.

Hypothesis: ER-localized PRDX4 is the dominant contributor to ER peroxide detoxification while a smaller cytosolic pool affects NF-kappaB redox signaling.

Type: Compartment-specific redox assay

Experiment: Test PRDX4 dimer/decamer interface mutants for peroxidase activity and overoxidation sensitivity in cells.

Hypothesis: PRDX4 oligomeric assembly is required for efficient thioredoxin-dependent peroxidase activity and controls susceptibility to overoxidation.

Type: Oligomerization mutant analysis

📚 Additional Documentation

Deep Research Falcon

(PRDX4-deep-research-falcon.md)

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organism: human
gene_id: PRDX4
gene_symbol: PRDX4
uniprot_accession: Q13162
protein_description: 'RecName: Full=Peroxiredoxin-4; EC=1.11.1.24 {ECO:0000269|PubMed:21916849,
ECO:0000269|PubMed:9388242}; AltName: Full=Antioxidant enzyme AOE372; Short=AOE37-2;
AltName: Full=Peroxiredoxin IV; Short=Prx-IV; AltName: Full=Thioredoxin peroxidase
AO372; AltName: Full=Thioredoxin-dependent peroxide reductase A0372; AltName:
Full=Thioredoxin-dependent peroxiredoxin 4 {ECO:0000305}; Flags: Precursor;'
gene_info: Name=PRDX4;
organism_full: Homo sapiens (Human).
protein_family: Belongs to the peroxiredoxin family. AhpC/Prx1 subfamily.
protein_domains: AhpC/TSA. (IPR000866); Peroxiredoxin. (IPR050217); Peroxiredoxin_C.
(IPR019479); Thioredoxin-like_sf. (IPR036249); Thioredoxin_domain. (IPR013766)
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Question

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

UniProt Accession: Q13162
Protein Description: RecName: Full=Peroxiredoxin-4; EC=1.11.1.24 {ECO:0000269|PubMed:21916849, ECO:0000269|PubMed:9388242}; AltName: Full=Antioxidant enzyme AOE372; Short=AOE37-2; AltName: Full=Peroxiredoxin IV; Short=Prx-IV; AltName: Full=Thioredoxin peroxidase AO372; AltName: Full=Thioredoxin-dependent peroxide reductase A0372; AltName: Full=Thioredoxin-dependent peroxiredoxin 4 {ECO:0000305}; Flags: Precursor;
Gene Information: Name=PRDX4;
Organism (full): Homo sapiens (Human).
Protein Family: Belongs to the peroxiredoxin family. AhpC/Prx1 subfamily.
Key Domains: AhpC/TSA. (IPR000866); Peroxiredoxin. (IPR050217); Peroxiredoxin_C. (IPR019479); Thioredoxin-like_sf. (IPR036249); Thioredoxin_domain. (IPR013766)

MANDATORY VERIFICATION STEPS:

Check if the gene symbol "PRDX4" matches the protein description above
Verify the organism is correct: Homo sapiens (Human).
Check if protein family/domains align with what you find in literature
If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'PRDX4' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

Research Target:

Please provide a comprehensive research report on the gene PRDX4 (gene ID: PRDX4, UniProt: Q13162) in human.

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.

Output

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on:
1. Key concepts and definitions with current understanding
2. Recent developments and latest research (prioritize 2023-2024 sources)
3. Current applications and real-world implementations
4. Expert opinions and analysis from authoritative sources
5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available.
Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

UniProt Accession: Q13162
Protein Description: RecName: Full=Peroxiredoxin-4; EC=1.11.1.24 {ECO:0000269|PubMed:21916849, ECO:0000269|PubMed:9388242}; AltName: Full=Antioxidant enzyme AOE372; Short=AOE37-2; AltName: Full=Peroxiredoxin IV; Short=Prx-IV; AltName: Full=Thioredoxin peroxidase AO372; AltName: Full=Thioredoxin-dependent peroxide reductase A0372; AltName: Full=Thioredoxin-dependent peroxiredoxin 4 {ECO:0000305}; Flags: Precursor;
Gene Information: Name=PRDX4;
Organism (full): Homo sapiens (Human).
Protein Family: Belongs to the peroxiredoxin family. AhpC/Prx1 subfamily.
Key Domains: AhpC/TSA. (IPR000866); Peroxiredoxin. (IPR050217); Peroxiredoxin_C. (IPR019479); Thioredoxin-like_sf. (IPR036249); Thioredoxin_domain. (IPR013766)

MANDATORY VERIFICATION STEPS:

Check if the gene symbol "PRDX4" matches the protein description above
Verify the organism is correct: Homo sapiens (Human).
Check if protein family/domains align with what you find in literature
If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

Research Target:

Please provide a comprehensive research report on the gene PRDX4 (gene ID: PRDX4, UniProt: Q13162) in human.

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.

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.

Comprehensive Functional-Annotation Research Report: Human PRDX4 (Peroxiredoxin-4; UniProt Q13162)

0) Target identity verification (critical disambiguation)

The UniProt accession Q13162 corresponds to Homo sapiens PRDX4, whose recommended name is Peroxiredoxin-4 (PrxIV), a typical 2-Cys peroxiredoxin that is primarily localized to the endoplasmic reticulum (ER) and can also be secreted/extracellular. This identity is directly supported by a 2024 human proteomics study listing PRDX4 = Q13162 (giuseppe2024changesinducedby pages 8-10) and by a PRDX4-focused review describing human PRDX4/Prx4 as an ER-localized typical 2-Cys peroxiredoxin and discussing its specific isoforms and ER targeting (thapa2022essentialrolesof pages 1-2, thapa2022essentialrolesof pages 2-4).

1) Key concepts and definitions (current understanding)

1.1 Peroxiredoxins and “typical 2-Cys” peroxiredoxins

Peroxiredoxins (PRDXs) are thiol-based peroxidases that reduce peroxides using catalytic cysteine residues. PRDX1–4 are classified as typical 2-Cys PRDXs, forming an intersubunit disulfide between the peroxidatic cysteine (Cp) and resolving cysteine (Cr) during catalysis (thapa2022essentialrolesof pages 1-2, karpenko2021peroxiredoxins—theunderratedactors pages 2-3).

1.2 What makes PRDX4 distinct among human PRDXs

A distinguishing feature emphasized in the PRDX4 literature is its ER luminal localization (often described as the only peroxiredoxin isoform primarily localized to the ER) and its coupling to oxidative protein folding in the secretory pathway, with the additional property that it can appear in extracellular compartments (thapa2022essentialrolesof pages 1-2, thapa2022essentialrolesof pages 2-4).

2) Molecular function: enzymatic reaction, mechanism, and substrate specificity

2.1 Enzymatic activity and reaction chemistry

PRDX4 catalyzes peroxide reduction through the canonical typical 2-Cys cycle: the peroxidatic cysteine is oxidized by H2O2 to cysteine sulfenic acid (Cp–SOH); then the resolving cysteine from the partner subunit attacks to form an intersubunit disulfide, while H2O2 is reduced to water (thapa2022essentialrolesof pages 2-4). A review further notes that peroxiredoxins (including PRDX4) reduce not only hydrogen peroxide but also other peroxides such as alkyl hydroperoxides and peroxynitrite (family-level statement) (thapa2022essentialrolesof pages 1-2). Experimentally, PRDX4 is clearly reactive to both H2O2 and tert-butyl hydroperoxide, as used in a mechanistic cell/biochemistry study (elko2021oxidationofperoxiredoxin4 pages 10-11).

2.2 Electron donors and recycling partners (thioredoxin/PDI-linked redox systems)

After PRDX4 forms the intersubunit disulfide, it must be reduced to return to the active peroxidatic form. For PRDX4, reduction/recycling can proceed via thioredoxin (Trx), glutathione (GSH), protein disulfide isomerase (PDI), and other ER oxidoreductases (thapa2022essentialrolesof pages 2-4). In the ER, PRDX4 is described as functionally integrated with PDI-family proteins, where PRDX4 transfers oxidizing equivalents/disulfides to PDI family members to support oxidative protein folding (moilanen2021novelregulatorymechanisms pages 50-53, ong2023unfoldingtheinteractions pages 1-2).

2.3 Kinetics and quantitative enzymology

A PRDX4-focused review reports a second-order rate constant for PRDX4-mediated H2O2 reduction of 2.2 × 10^7 M⁻1·s⁻1, and contrasts this with much slower reactions attributed to GSH and Trx in the cited comparison, as well as a lower activity reported for another ER antioxidant (GPx8, 95 M⁻1·s⁻1) (thapa2022essentialrolesof pages 2-4). These values support PRDX4 as a highly efficient ER peroxide scavenger.

2.4 Hyperoxidation, inactivation, and functional switching (peroxidase ↔ chaperone)

At higher peroxide levels, PRDX4 can become hyperoxidized (e.g., to sulfinic and sulfonic acid forms), leading to loss of peroxidase activity; the sulfinic form can be repaired by sulfiredoxin (Srx) (thapa2022essentialrolesof pages 2-4). A 2023 review of ER stress/oxidative stress emphasizes that high H2O2 can induce superoxidation (hyperoxidation) of PRDX4, thereby inactivating it and contributing to a ROS–ER stress feedback loop (ong2023unfoldingtheinteractions pages 5-7).

3) Cellular localization and where PRDX4 acts

3.1 ER luminal targeting and retention versus secretion

PRDX4 is localized mainly to the endoplasmic reticulum, enabled by an N-terminal region that supports translocation into the ER lumen (thapa2022essentialrolesof pages 2-4). Despite lacking the canonical KDEL ER-retention motif, PRDX4 ER localization is attributed to interactions with PDI and ERp44; perturbations of these components (e.g., ERGIC-53 knockdown, chemical chaperone exposure) can increase PRDX4 secretion, while ERp44/PDI overexpression can suppress secretion (thapa2022essentialrolesof pages 2-4). PRDX4’s presence in the extracellular environment is consistent with its reported secretion (thapa2022essentialrolesof pages 2-4, elko2021oxidationofperoxiredoxin4 pages 11-12).

3.2 Isoforms and compartment-specific implications

A testis-associated isoform, Prx4t, is described as lacking the N-terminal signal peptide and therefore localized to the cytosol rather than the ER (thapa2022essentialrolesof pages 2-4). The PRDX4/Prx4 isoform context is important for interpreting expression/localization data in tissue-specific studies.

4) Pathways and biological processes: oxidative protein folding and ER redox homeostasis

4.1 Integration into oxidative folding pathways (ERO1–PDI axis and PRDX4)

Oxidative protein folding in the ER involves PDI-family members introducing disulfides into nascent proteins. A central oxidase, ERO1, re-oxidizes PDI and in doing so generates H2O2 as a byproduct (thapa2022essentialrolesof pages 2-4). A major contemporary view is that ER-resident peroxidases (including PRDX4) use this peroxide product to both detoxify it and to re-oxidize PDIs, thereby coupling peroxide consumption to disulfide-bond formation (ong2023unfoldingtheinteractions pages 1-2). More broadly, PRDX4 is described as an ER-resident antioxidant and oxidative folding enzyme acting in cyclic redox pathways with PDIs (ong2023unfoldingtheinteractions pages 1-2).

4.2 ERO1-independent H2O2 supply and PRDX4-mediated folding

A mechanistic primary study shows that PRDX4 can sustain disulfide bond formation in the absence of ERO1 and provides evidence for an ER-localized, ERO1-independent source of H2O2 that fuels PRDX4-mediated disulfide bond formation (konno2015ero1independentproductionof pages 1-2). This supports PRDX4 as a flexible component of ER redox homeostasis, not solely dependent on ERO1-derived peroxide.

4.3 ER stress/UPR linkage: redox feedback loops that involve PRDX4

A 2023 review links the unfolded protein response (UPR) to oxidative stress via CHOP-driven induction of ERO1, increasing H2O2 production during oxidative folding. In this framing, high H2O2 can inactivate PRDX4 (hyperoxidation), helping sustain a vicious cycle of ER stress, Ca2+ dysregulation, and mitochondrial ROS amplification (ong2023unfoldingtheinteractions pages 5-7).

5) Recent developments and latest research (prioritizing 2023–2024)

5.1 2023: Systems-level framing of PRDX4 within ER stress and oxidative stress

Ong & Logue (Antioxidants, April 2023) synthesize evidence that PRDX4 participates in oxidative protein folding by using ERO1-generated H2O2 to help recycle PDIs and maintain ER redox balance, and they cite the ER as a major ROS source (reported as ~25% in their review) (ong2023unfoldingtheinteractions pages 1-2). They also emphasize PRDX4 hyperoxidation/inactivation under high H2O2 in the context of ER-stress amplification (ong2023unfoldingtheinteractions pages 5-7). URL: https://doi.org/10.3390/antiox12050981 (ong2023unfoldingtheinteractions pages 1-2).

5.2 2024: PRDX4 in cancer-redox discussions as a compensatory ER oxidoreductase

Chen et al. (Journal of Experimental & Clinical Cancer Research, March 2024) review the ERO1α–PDI axis in cancer and explicitly list PRDX4 among oxidoreductases/peroxireductases that can compensate for ERO1α-dependent oxidative folding. They further discuss that inhibition of ERO1α can impair oxidative folding of some pro-tumoral proteins in cancer, suggesting backup systems (including PRDX4) may be insufficient/dysfunctional in tumor contexts (chen2024biologicalmechanismsand pages 3-4, chen2024biologicalmechanismsand pages 4-6). URL: https://doi.org/10.1186/s13046-024-02990-4 (chen2024biologicalmechanismsand pages 1-3).

5.3 2024: PRDX4 detection in extracellular vesicles (real-world proteomics implementation)

A 2024 proteomic study of extracellular vesicles (EVs) from glioblastoma stem cells (Cells, March 2024) identifies PRDX4 (Q13162) as upregulated in EVs after P2X7 receptor stimulation (BzATP). PRDX4 appears in both microvesicle and exosome-associated datasets with multiple peptides and statistically significant changes: e.g., for microvesicles, 15 matched peptides, 64% sequence coverage, p = 0.0007; for an exosome/matched set, 11 matched peptides, 43% sequence coverage, p = 0.0005 (giuseppe2024changesinducedby pages 8-10). This provides a concrete example of PRDX4 being measured in a real biological secretome/EV implementation, consistent with its known secreted/extracellular presence. URL: https://doi.org/10.3390/cells13070571 (giuseppe2024changesinducedby pages 8-10).

6) Current applications and real-world implementations

6.1 Biomarker-oriented measurements in secreted/extracellular compartments

PRDX4 is described as a secretable protein and has been investigated as a circulating/serum oxidative stress marker in the PRDX4 literature summarized in a mechanistic paper’s referenced context (elko2021oxidationofperoxiredoxin4 pages 11-12). The 2024 EV proteomics study provides an implementation example: PRDX4 is detectable and significantly modulated in tumor-derived EVs (giuseppe2024changesinducedby pages 8-10).

6.2 Targetable ER redox dependencies in cancer biology (expert synthesis)

Cancer-focused reviews emphasize ER oxidative folding systems (ERO1α/PDI axis) as potential targets and explicitly recognize PRDX4 as part of the redundant ER peroxide-handling/oxidative folding network (chen2024biologicalmechanismsand pages 3-4, chen2024biologicalmechanismsand pages 4-6). This supports the interpretation that PRDX4 may influence tumor cell fitness under ER stress and oxidative folding demands, and that tumor-specific failures of compensatory redox pathways could create vulnerabilities.

7) Expert opinions and authoritative synthesis

7.1 PRDX4 as a node coupling peroxide detoxification to productive oxidative folding

An authoritative 2023 review argues that enzymes like PRDX4 (and related ER peroxidases) are not merely “antioxidants,” but are integrated into oxidative folding cycles by using ERO1-derived peroxide as an electron acceptor to recycle oxidized PDI states (ong2023unfoldingtheinteractions pages 1-2). This conceptual model positions PRDX4 at the intersection of redox detoxification and secretory pathway proteostasis.

7.2 PRDX4 in ER stress–oxidative stress feedback loops

The same review frames PRDX4 inactivation by hyperoxidation as a mechanism that can exacerbate ER stress under high ROS, contributing to a feed-forward loop involving CHOP→ERO1→H2O2 and mitochondrial ROS amplification (ong2023unfoldingtheinteractions pages 5-7). This highlights that PRDX4’s redox state can shift cells between adaptive and maladaptive outcomes during proteostatic stress.

8) Relevant statistics and data highlights (from recent and foundational sources)

PRDX4 H2O2 reduction rate constant: 2.2 × 10^7 M⁻1·s⁻1 (thapa2022essentialrolesof pages 2-4).
ER contribution to cellular ROS/H2O2: reported as “around 25%” in a 2023 review (ong2023unfoldingtheinteractions pages 1-2) and similarly noted in a 2024 cancer review in the context of ERO1α being a major H2O2 source (chen2024biologicalmechanismsand pages 3-4).
2024 EV proteomics statistics for PRDX4 (glioblastoma stem cell EVs): upregulated with p = 0.0007 (MVs; 15 peptides; 64% sequence coverage) and p = 0.0005 (EXO/matched set; 11 peptides; 43% coverage) (giuseppe2024changesinducedby pages 8-10).

9) Summary functional annotation (actionable for gene/protein annotation)

Primary molecular function: ER-lumen thiol-dependent peroxidase that reduces H2O2 → H2O via a typical 2-Cys PRDX mechanism (Cp/Cr intersubunit disulfide), and whose oxidized form is recycled by Trx/GSH/PDI-family redox systems (thapa2022essentialrolesof pages 2-4).

Primary biological role: maintains ER redox homeostasis and supports oxidative protein folding by coupling peroxide detoxification to PDI re-oxidation/disulfide transfer, with both ERO1-dependent and ERO1-independent peroxide supply routes described (ong2023unfoldingtheinteractions pages 1-2, konno2015ero1independentproductionof pages 1-2).

Cellular site of action: predominantly the ER lumen, with regulated retention through ER chaperone/oxidoreductase interactions and a capacity for secretion/extracellular presence; a testis isoform is cytosolic (thapa2022essentialrolesof pages 2-4).

Embedded evidence summary table

Category	Key points	Best supporting citations (pqac IDs)	Source URL + year
Identity	PRDX4 matches UniProt Q13162 as human Peroxiredoxin-4/PrxIV, a typical 2-Cys peroxiredoxin and the only PRDX isoform primarily localized to the ER; structurally forms dimers/decamers with thioredoxin-fold subunits.	(thapa2022essentialrolesof pages 1-2, thapa2022essentialrolesof pages 2-4)	https://doi.org/10.3390/molecules27196513 (2022)
Localization	PRDX4 is mainly in the ER lumen via an extended N-terminal signal sequence; despite lacking KDEL, ER retention depends on interactions with PDI and ERp44. It can also be secreted/extracellular, and a testis isoform lacking the signal peptide is cytosolic.	(thapa2022essentialrolesof pages 2-4)	https://doi.org/10.3390/molecules27196513 (2022)
Enzymatic reaction	Thiol-dependent peroxidase that reduces H2O2 to water via oxidation of the peroxidatic cysteine to sulfenic acid followed by intersubunit disulfide formation with the resolving cysteine; broader peroxiredoxin family activity includes alkyl hydroperoxides/peroxynitrite, and PRDX4 is experimentally reactive to H2O2 and tert-butyl hydroperoxide.	(thapa2022essentialrolesof pages 2-4, thapa2022essentialrolesof pages 1-2, elko2021oxidationofperoxiredoxin4 pages 10-11)	https://doi.org/10.3390/molecules27196513 (2022); https://doi.org/10.1016/j.jbc.2021.100665 (2021)
Mechanism & partners	Oxidized PRDX4 is reduced by Trx, GSH, PDI, or other ER oxidoreductases. In the ER it couples peroxide detoxification to oxidative folding by oxidizing/re-oxidizing PDI family proteins; substrate preference reported for ERp46 and P5 over PDI in one source. Oxidation can induce oligomerization and increased interaction with protein-folding/ER-stress machinery.	(thapa2022essentialrolesof pages 2-4, moilanen2021novelregulatorymechanisms pages 50-53, thapa2022essentialrolesof pages 18-19, elko2021oxidationofperoxiredoxin4 pages 10-11, ong2023unfoldingtheinteractions pages 1-2)	https://doi.org/10.3390/molecules27196513 (2022); https://doi.org/10.1016/j.jbc.2021.100665 (2021); https://doi.org/10.3390/antiox12050981 (2023)
Physiology & pathways	PRDX4 scavenges ERO1-generated H2O2 and supports oxidative protein folding of secreted/membrane proteins in the ER. It can also support an ERO1-independent H2O2-fueled oxidative folding pathway. During ER stress/UPR, excess H2O2 can hyperoxidize and inactivate PRDX4, linking it to ROS–ER stress feedback loops.	(thapa2022essentialrolesof pages 2-4, konno2015ero1independentproductionof pages 1-2, ong2023unfoldingtheinteractions pages 1-2, ong2023unfoldingtheinteractions pages 5-7, ong2023unfoldingtheinteractions pages 8-10)	https://doi.org/10.3390/molecules27196513 (2022); https://doi.org/10.1083/jcb.201506123 (2015); https://doi.org/10.3390/antiox12050981 (2023)
Disease & applications	Reviews link PRDX4 to inflammation, ER-stress protection, and cancer biology. Cited studies report worsened DSS-colitis in Prdx4-knockout mice, learning/memory defects in deficiency, and cancer-related roles in HCC, glioma, pancreatic cancer redox vulnerability, plus extracellular/serum biomarker potential.	(bidooki2024thioredoxindomaincontaining pages 23-24, elko2021oxidationofperoxiredoxin4 pages 11-12, thapa2022essentialrolesof pages 23-23)	https://doi.org/10.3390/cimb46040197 (2024); https://doi.org/10.3390/molecules27196513 (2022); https://doi.org/10.1016/j.jbc.2021.100665 (2021)
Recent quantitative data 2023-2024	2023 review: ER contributes ~25% of cellular ROS/H2O2 and PRDX4 uses ERO1-generated H2O2 to re-oxidize PDIs during folding. 2024 EV proteomics: PRDX4 was significantly upregulated in glioblastoma stem cell EVs after P2X7 stimulation—MVs spot M11 score 82, 15 matched peptides, 64% sequence coverage, p=0.0007; exosome/matched spot L13 score 63, 11 matched peptides, 43% coverage, p=0.0005.	(ong2023unfoldingtheinteractions pages 1-2, giuseppe2024changesinducedby pages 8-10, chen2024biologicalmechanismsand pages 3-4)	https://doi.org/10.3390/antiox12050981 (2023); https://doi.org/10.3390/cells13070571 (2024); https://doi.org/10.1186/s13046-024-02990-4 (2024)

Table: This table summarizes the core functional annotation of human PRDX4 (UniProt Q13162), including identity, localization, enzymatic function, mechanistic partners, pathways, disease relevance, and recent quantitative evidence from 2023-2024 sources.

Key figures (mechanism and isoform schematic)

PRDX4 catalytic cycle schematic (H2O2 reduction, hyperoxidation, and functional switching) (thapa2022essentialrolesof media b6f51c4f).

PRDX4 alternative splicing schematic (systemic Prx4 vs testis Prx4t) (thapa2022essentialrolesof media ef3d3b84).

References (URLs and publication dates)

Ong, G.; Logue, S.E. Unfolding the interactions between endoplasmic reticulum stress and oxidative stress. Antioxidants (Apr 2023). https://doi.org/10.3390/antiox12050981 (ong2023unfoldingtheinteractions pages 1-2)
Chen, P. et al. Biological mechanisms and clinical significance of ERO1α in human cancer. J Exp Clin Cancer Res (Mar 2024). https://doi.org/10.1186/s13046-024-02990-4 (chen2024biologicalmechanismsand pages 1-3)
Di Giuseppe, F. et al. Changes induced by P2X7 receptor stimulation… EV proteome… Cells (Mar 2024). https://doi.org/10.3390/cells13070571 (giuseppe2024changesinducedby pages 8-10)
Thapa, P. et al. Essential roles of peroxiredoxin IV in inflammation and cancer. Molecules (Oct 2022). https://doi.org/10.3390/molecules27196513 (thapa2022essentialrolesof pages 2-4)
Konno, T. et al. ERO1-independent production of H2O2 within the ER fuels Prdx4-mediated oxidative protein folding. J Cell Biol (Oct 2015). https://doi.org/10.1083/jcb.201506123 (konno2015ero1independentproductionof pages 1-2)
Elko, E.A. et al. Oxidation of PRDX4 induces oligomerization… ER stress. J Biol Chem (Apr 2021). https://doi.org/10.1016/j.jbc.2021.100665 (elko2021oxidationofperoxiredoxin4 pages 10-11)

References

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(thapa2022essentialrolesof pages 2-4): Pratik Thapa, Na Ding, Yanning Hao, Aziza Alshahrani, Hong Jiang, and Qiou Wei. Essential roles of peroxiredoxin iv in inflammation and cancer. Molecules, 27:6513, Oct 2022. URL: https://doi.org/10.3390/molecules27196513, doi:10.3390/molecules27196513. This article has 22 citations.
(karpenko2021peroxiredoxins—theunderratedactors pages 2-3): Inna L. Karpenko, Vladimir T. Valuev-Elliston, Olga N. Ivanova, Olga A. Smirnova, and Alexander V. Ivanov. Peroxiredoxins—the underrated actors during virus-induced oxidative stress. Antioxidants, 10:977, Jun 2021. URL: https://doi.org/10.3390/antiox10060977, doi:10.3390/antiox10060977. This article has 39 citations.
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(chen2024biologicalmechanismsand pages 3-4): Peng Chen, Amit Sharma, Hans Weiher, and Ingo G.H. Schmidt-Wolf. Biological mechanisms and clinical significance of endoplasmic reticulum oxidoreductase 1 alpha (ero1α) in human cancer. Journal of Experimental & Clinical Cancer Research : CR, Mar 2024. URL: https://doi.org/10.1186/s13046-024-02990-4, doi:10.1186/s13046-024-02990-4. This article has 27 citations.
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(chen2024biologicalmechanismsand pages 1-3): Peng Chen, Amit Sharma, Hans Weiher, and Ingo G.H. Schmidt-Wolf. Biological mechanisms and clinical significance of endoplasmic reticulum oxidoreductase 1 alpha (ero1α) in human cancer. Journal of Experimental & Clinical Cancer Research : CR, Mar 2024. URL: https://doi.org/10.1186/s13046-024-02990-4, doi:10.1186/s13046-024-02990-4. This article has 27 citations.
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(bidooki2024thioredoxindomaincontaining pages 23-24): Seyed Hesamoddin Bidooki, María A. Navarro, Susana C. M. Fernandes, and Jesus Osada. Thioredoxin domain containing 5 (txndc5): friend or foe? Current Issues in Molecular Biology, 46:3134-3163, Apr 2024. URL: https://doi.org/10.3390/cimb46040197, doi:10.3390/cimb46040197. This article has 14 citations.
(thapa2022essentialrolesof pages 23-23): Pratik Thapa, Na Ding, Yanning Hao, Aziza Alshahrani, Hong Jiang, and Qiou Wei. Essential roles of peroxiredoxin iv in inflammation and cancer. Molecules, 27:6513, Oct 2022. URL: https://doi.org/10.3390/molecules27196513, doi:10.3390/molecules27196513. This article has 22 citations.
(thapa2022essentialrolesof media b6f51c4f): Pratik Thapa, Na Ding, Yanning Hao, Aziza Alshahrani, Hong Jiang, and Qiou Wei. Essential roles of peroxiredoxin iv in inflammation and cancer. Molecules, 27:6513, Oct 2022. URL: https://doi.org/10.3390/molecules27196513, doi:10.3390/molecules27196513. This article has 22 citations.
(thapa2022essentialrolesof media ef3d3b84): Pratik Thapa, Na Ding, Yanning Hao, Aziza Alshahrani, Hong Jiang, and Qiou Wei. Essential roles of peroxiredoxin iv in inflammation and cancer. Molecules, 27:6513, Oct 2022. URL: https://doi.org/10.3390/molecules27196513, doi:10.3390/molecules27196513. This article has 22 citations.

Citations

giuseppe2024changesinducedby pages 8-10
thapa2022essentialrolesof pages 2-4
thapa2022essentialrolesof pages 1-2
ong2023unfoldingtheinteractions pages 5-7
ong2023unfoldingtheinteractions pages 1-2
chen2024biologicalmechanismsand pages 1-3
chen2024biologicalmechanismsand pages 3-4
moilanen2021novelregulatorymechanisms pages 50-53
chen2024biologicalmechanismsand pages 4-6
thapa2022essentialrolesof pages 18-19
ong2023unfoldingtheinteractions pages 8-10
bidooki2024thioredoxindomaincontaining pages 23-24
thapa2022essentialrolesof pages 23-23
https://doi.org/10.3390/antiox12050981
https://doi.org/10.1186/s13046-024-02990-4
https://doi.org/10.3390/cells13070571
https://doi.org/10.3390/molecules27196513
https://doi.org/10.1016/j.jbc.2021.100665
https://doi.org/10.1083/jcb.201506123
https://doi.org/10.3390/cimb46040197
https://doi.org/10.3390/cells13070571,
https://doi.org/10.3390/molecules27196513,
https://doi.org/10.3390/antiox10060977,
https://doi.org/10.1016/j.jbc.2021.100665,
https://doi.org/10.3390/antiox12050981,
https://doi.org/10.1083/jcb.201506123,
https://doi.org/10.1186/s13046-024-02990-4,
https://doi.org/10.3390/cimb46040197,

📄 View Raw YAML

id: Q13162
gene_symbol: PRDX4
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: >-
  PRDX4 encodes peroxiredoxin-4, a typical 2-Cys thioredoxin-dependent peroxidase that reduces hydrogen
  peroxide and organic hydroperoxides. It is cotranslationally translocated to and retained mainly in
  the endoplasmic reticulum, with a smaller cytoplasmic fraction that has been linked to redox modulation
  of NF-kappaB signaling. Its core annotation is thioredoxin-dependent peroxiredoxin/peroxidase activity
  in peroxide detoxification and redox homeostasis, not generic protein binding.
existing_annotations:
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      cytosol localization is supported for a smaller PRDX4 pool, including the cytoplasmic fraction implicated
      in NF-kappaB redox modulation.
    action: ACCEPT
    reason: >-
      Although the endoplasmic reticulum is the dominant core location, UniProt and experimental literature
      support a cytoplasmic fraction. The term is therefore valid, with ER retained as the primary localization.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        SUBCELLULAR LOCATION: Cytoplasm. Endoplasmic reticulum. Note=A small fraction of the protein is
        cytoplasmic.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report emphasizes ER localization as primary while noting additional cytosolic or secreted/extracellular
        PRDX4 contexts.
- term:
    id: GO:0006979
    label: response to oxidative stress
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      response to oxidative stress is supported by PRDX4 peroxide-reducing activity and its role in cellular
      redox protection.
    action: ACCEPT
    reason: >-
      PRDX4 directly detoxifies hydroperoxides through the thioredoxin system, so these redox and peroxide
      catabolic process annotations are appropriate biological-process summaries.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        Plays a role in cell protection against oxidative stress by detoxifying peroxides and as sensor
        of hydrogen peroxide-mediated signaling events.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and other hydroperoxides
        and supports ER redox/proteostasis biology.
- term:
    id: GO:0008379
    label: thioredoxin peroxidase activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      thioredoxin peroxidase activity accurately captures PRDX4 catalysis as a thioredoxin-dependent 2-Cys
      peroxiredoxin that reduces hydroperoxides.
    action: ACCEPT
    reason: >-
      This is the core molecular function of PRDX4 and is supported by both the original thioredoxin peroxidase
      study and structural/catalytic analysis.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        Reaction=a hydroperoxide + [thioredoxin]-dithiol = an alcohol + [thioredoxin]-disulfide + H2O;
        EC=1.11.1.24.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and other hydroperoxides
        and supports ER redox/proteostasis biology.
- term:
    id: GO:0042744
    label: hydrogen peroxide catabolic process
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      hydrogen peroxide catabolic process is supported by PRDX4 peroxide-reducing activity and its role
      in cellular redox protection.
    action: ACCEPT
    reason: >-
      PRDX4 directly detoxifies hydroperoxides through the thioredoxin system, so these redox and peroxide
      catabolic process annotations are appropriate biological-process summaries.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        Plays a role in cell protection against oxidative stress by detoxifying peroxides and as sensor
        of hydrogen peroxide-mediated signaling events.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and other hydroperoxides
        and supports ER redox/proteostasis biology.
- term:
    id: GO:0045454
    label: cell redox homeostasis
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      cell redox homeostasis is supported by PRDX4 peroxide-reducing activity and its role in cellular
      redox protection.
    action: ACCEPT
    reason: >-
      PRDX4 directly detoxifies hydroperoxides through the thioredoxin system, so these redox and peroxide
      catabolic process annotations are appropriate biological-process summaries.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        Plays a role in cell protection against oxidative stress by detoxifying peroxides and as sensor
        of hydrogen peroxide-mediated signaling events.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and other hydroperoxides
        and supports ER redox/proteostasis biology.
- term:
    id: GO:0005783
    label: endoplasmic reticulum
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      Endoplasmic reticulum localization is a core location for PRDX4. UniProt states that PRDX4 is cotranslationally
      translocated to and retained within the ER.
    action: ACCEPT
    reason: >-
      This is the most informative cellular component for PRDX4 and matches the enzyme biology as the
      ER-localized peroxiredoxin.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        SUBCELLULAR LOCATION: Cytoplasm. Endoplasmic reticulum. Note=Cotranslationally translocated to
        and retained within the endoplasmic reticulum.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report summarizes PRDX4 as localized mainly to the endoplasmic reticulum, with ER luminal
        targeting and retention through oxidoreductase/chaperone interactions.
- term:
    id: GO:0098869
    label: cellular oxidant detoxification
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: >-
      cellular oxidant detoxification is supported by PRDX4 peroxide-reducing activity and its role in
      cellular redox protection.
    action: ACCEPT
    reason: >-
      PRDX4 directly detoxifies hydroperoxides through the thioredoxin system, so these redox and peroxide
      catabolic process annotations are appropriate biological-process summaries.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        Plays a role in cell protection against oxidative stress by detoxifying peroxides and as sensor
        of hydrogen peroxide-mediated signaling events.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and other hydroperoxides
        and supports ER redox/proteostasis biology.
- term:
    id: GO:0004601
    label: peroxidase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000043
  review:
    summary: >-
      peroxidase activity is compatible with PRDX4 biology but is a broad parent or less-informative activity
      compared with the specific thioredoxin-dependent peroxiredoxin annotations already present.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      The precise MF terms GO:0140824/GO:0051920/GO:0008379 better represent PRDX4. Broad antioxidant/peroxidase/oxidoreductase
      terms add little specificity.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        PRDX4 is annotated as a thiol-specific peroxidase that reduces hydrogen peroxide and organic hydroperoxides.
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: >-
      cytoplasm localization is supported for a smaller PRDX4 pool, including the cytoplasmic fraction
      implicated in NF-kappaB redox modulation.
    action: ACCEPT
    reason: >-
      Although the endoplasmic reticulum is the dominant core location, UniProt and experimental literature
      support a cytoplasmic fraction. The term is therefore valid, with ER retained as the primary localization.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        SUBCELLULAR LOCATION: Cytoplasm. Endoplasmic reticulum. Note=A small fraction of the protein is
        cytoplasmic.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report emphasizes ER localization as primary while noting additional cytosolic or secreted/extracellular
        PRDX4 contexts.
- term:
    id: GO:0005783
    label: endoplasmic reticulum
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: >-
      Endoplasmic reticulum localization is a core location for PRDX4. UniProt states that PRDX4 is cotranslationally
      translocated to and retained within the ER.
    action: ACCEPT
    reason: >-
      This is the most informative cellular component for PRDX4 and matches the enzyme biology as the
      ER-localized peroxiredoxin.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        SUBCELLULAR LOCATION: Cytoplasm. Endoplasmic reticulum. Note=Cotranslationally translocated to
        and retained within the endoplasmic reticulum.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report summarizes PRDX4 as localized mainly to the endoplasmic reticulum, with ER luminal
        targeting and retention through oxidoreductase/chaperone interactions.
- term:
    id: GO:0016209
    label: antioxidant activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: >-
      antioxidant activity is compatible with PRDX4 biology but is a broad parent or less-informative
      activity compared with the specific thioredoxin-dependent peroxiredoxin annotations already present.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      The precise MF terms GO:0140824/GO:0051920/GO:0008379 better represent PRDX4. Broad antioxidant/peroxidase/oxidoreductase
      terms add little specificity.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        PRDX4 is annotated as a thiol-specific peroxidase that reduces hydrogen peroxide and organic hydroperoxides.
- term:
    id: GO:0016491
    label: oxidoreductase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: >-
      oxidoreductase activity is compatible with PRDX4 biology but is a broad parent or less-informative
      activity compared with the specific thioredoxin-dependent peroxiredoxin annotations already present.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      The precise MF terms GO:0140824/GO:0051920/GO:0008379 better represent PRDX4. Broad antioxidant/peroxidase/oxidoreductase
      terms add little specificity.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        PRDX4 is annotated as a thiol-specific peroxidase that reduces hydrogen peroxide and organic hydroperoxides.
- term:
    id: GO:0051920
    label: peroxiredoxin activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  review:
    summary: >-
      peroxiredoxin activity accurately captures PRDX4 catalysis as a thioredoxin-dependent 2-Cys peroxiredoxin
      that reduces hydroperoxides.
    action: ACCEPT
    reason: >-
      This is the core molecular function of PRDX4 and is supported by both the original thioredoxin peroxidase
      study and structural/catalytic analysis.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        Reaction=a hydroperoxide + [thioredoxin]-dithiol = an alcohol + [thioredoxin]-disulfide + H2O;
        EC=1.11.1.24.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and other hydroperoxides
        and supports ER redox/proteostasis biology.
- term:
    id: GO:0140824
    label: thioredoxin-dependent peroxiredoxin activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: >-
      thioredoxin-dependent peroxiredoxin activity accurately captures PRDX4 catalysis as a thioredoxin-dependent
      2-Cys peroxiredoxin that reduces hydroperoxides.
    action: ACCEPT
    reason: >-
      This is the core molecular function of PRDX4 and is supported by both the original thioredoxin peroxidase
      study and structural/catalytic analysis.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        Reaction=a hydroperoxide + [thioredoxin]-dithiol = an alcohol + [thioredoxin]-disulfide + H2O;
        EC=1.11.1.24.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and other hydroperoxides
        and supports ER redox/proteostasis biology.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:17644091
  review:
    summary: >-
      Generic protein binding from interactome evidence does not describe the specific PRDX4 molecular
      function.
    action: MARK_AS_OVER_ANNOTATED
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        The curated function describes thioredoxin-dependent peroxidase activity; interaction rows are
        partner lists rather than specific functional annotations.
    reason: >-
      PRDX4 has biologically relevant partners and oligomerization, but GO:0005515 is too vague. Specific
      terms for peroxiredoxin activity and identical protein binding capture the supported function better.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:21057456
  review:
    summary: >-
      Generic protein binding from interactome evidence does not describe the specific PRDX4 molecular
      function.
    action: MARK_AS_OVER_ANNOTATED
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        The curated function describes thioredoxin-dependent peroxidase activity; interaction rows are
        partner lists rather than specific functional annotations.
    reason: >-
      PRDX4 has biologically relevant partners and oligomerization, but GO:0005515 is too vague. Specific
      terms for peroxiredoxin activity and identical protein binding capture the supported function better.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:21988832
  review:
    summary: >-
      Generic protein binding from interactome evidence does not describe the specific PRDX4 molecular
      function.
    action: MARK_AS_OVER_ANNOTATED
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        The curated function describes thioredoxin-dependent peroxidase activity; interaction rows are
        partner lists rather than specific functional annotations.
    reason: >-
      PRDX4 has biologically relevant partners and oligomerization, but GO:0005515 is too vague. Specific
      terms for peroxiredoxin activity and identical protein binding capture the supported function better.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:25959826
  review:
    summary: >-
      Generic protein binding from interactome evidence does not describe the specific PRDX4 molecular
      function.
    action: MARK_AS_OVER_ANNOTATED
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        The curated function describes thioredoxin-dependent peroxidase activity; interaction rows are
        partner lists rather than specific functional annotations.
    reason: >-
      PRDX4 has biologically relevant partners and oligomerization, but GO:0005515 is too vague. Specific
      terms for peroxiredoxin activity and identical protein binding capture the supported function better.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:32814053
  review:
    summary: >-
      Generic protein binding from interactome evidence does not describe the specific PRDX4 molecular
      function.
    action: MARK_AS_OVER_ANNOTATED
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        The curated function describes thioredoxin-dependent peroxidase activity; interaction rows are
        partner lists rather than specific functional annotations.
    reason: >-
      PRDX4 has biologically relevant partners and oligomerization, but GO:0005515 is too vague. Specific
      terms for peroxiredoxin activity and identical protein binding capture the supported function better.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:33961781
  review:
    summary: >-
      Generic protein binding from interactome evidence does not describe the specific PRDX4 molecular
      function.
    action: MARK_AS_OVER_ANNOTATED
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        The curated function describes thioredoxin-dependent peroxidase activity; interaction rows are
        partner lists rather than specific functional annotations.
    reason: >-
      PRDX4 has biologically relevant partners and oligomerization, but GO:0005515 is too vague. Specific
      terms for peroxiredoxin activity and identical protein binding capture the supported function better.
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  review:
    summary: >-
      cytosol localization is supported for a smaller PRDX4 pool, including the cytoplasmic fraction implicated
      in NF-kappaB redox modulation.
    action: ACCEPT
    reason: >-
      Although the endoplasmic reticulum is the dominant core location, UniProt and experimental literature
      support a cytoplasmic fraction. The term is therefore valid, with ER retained as the primary localization.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        SUBCELLULAR LOCATION: Cytoplasm. Endoplasmic reticulum. Note=A small fraction of the protein is
        cytoplasmic.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report emphasizes ER localization as primary while noting additional cytosolic or secreted/extracellular
        PRDX4 contexts.
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  review:
    summary: >-
      Identical protein binding is supported by PRDX4 homodimerization and decamer formation, which are
      part of its 2-Cys peroxiredoxin catalytic assembly.
    action: ACCEPT
    reason: >-
      Unlike generic protein binding, identical protein binding is mechanistically informative for PRDX4
      because catalysis uses a dimeric interface and oxidized PRDX4 forms disulfide-linked homodimers/decamers.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        SUBUNIT: Homodimer; disulfide-linked, upon oxidation. 5 homodimers assemble to form a ring-like
        decamer.
- term:
    id: GO:0005783
    label: endoplasmic reticulum
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  review:
    summary: >-
      Endoplasmic reticulum localization is a core location for PRDX4. UniProt states that PRDX4 is cotranslationally
      translocated to and retained within the ER.
    action: ACCEPT
    reason: >-
      This is the most informative cellular component for PRDX4 and matches the enzyme biology as the
      ER-localized peroxiredoxin.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        SUBCELLULAR LOCATION: Cytoplasm. Endoplasmic reticulum. Note=Cotranslationally translocated to
        and retained within the endoplasmic reticulum.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report summarizes PRDX4 as localized mainly to the endoplasmic reticulum, with ER luminal
        targeting and retention through oxidoreductase/chaperone interactions.
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  review:
    summary: >-
      cytosol localization is supported for a smaller PRDX4 pool, including the cytoplasmic fraction implicated
      in NF-kappaB redox modulation.
    action: ACCEPT
    reason: >-
      Although the endoplasmic reticulum is the dominant core location, UniProt and experimental literature
      support a cytoplasmic fraction. The term is therefore valid, with ER retained as the primary localization.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        SUBCELLULAR LOCATION: Cytoplasm. Endoplasmic reticulum. Note=A small fraction of the protein is
        cytoplasmic.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report emphasizes ER localization as primary while noting additional cytosolic or secreted/extracellular
        PRDX4 contexts.
- term:
    id: GO:0060090
    label: molecular adaptor activity
  evidence_type: EXP
  original_reference_id: PMID:21916849
  review:
    summary: >-
      The cited structural study supports PRDX4 peroxidase catalysis, oligomerization, and overoxidation
      sensitivity, but it does not establish molecular adaptor activity as a distinct molecular function.
    action: MODIFY
    supported_by:
    - reference_id: PMID:21916849
      supporting_text: >-
        Prx4 exhibits a toroid-shaped decamer constructed of five catalytic dimers.
    reason: >-
      The biological evidence should be captured with a catalytic peroxiredoxin term rather than adaptor
      or sequestering activity. The best replacement is the specific thioredoxin-dependent peroxiredoxin
      activity term already supported by the same catalytic mechanism.
    proposed_replacement_terms:
    - id: GO:0140824
      label: thioredoxin-dependent peroxiredoxin activity
- term:
    id: GO:0140313
    label: molecular sequestering activity
  evidence_type: IDA
  original_reference_id: PMID:21916849
  review:
    summary: >-
      The cited structural study supports PRDX4 peroxidase catalysis, oligomerization, and overoxidation
      sensitivity, but it does not establish molecular sequestering activity as a distinct molecular function.
    action: MODIFY
    supported_by:
    - reference_id: PMID:21916849
      supporting_text: >-
        Prx4 exhibits a toroid-shaped decamer constructed of five catalytic dimers.
    reason: >-
      The biological evidence should be captured with a catalytic peroxiredoxin term rather than adaptor
      or sequestering activity. The best replacement is the specific thioredoxin-dependent peroxiredoxin
      activity term already supported by the same catalytic mechanism.
    proposed_replacement_terms:
    - id: GO:0140824
      label: thioredoxin-dependent peroxiredoxin activity
- term:
    id: GO:0005576
    label: extracellular region
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-6798748
  review:
    summary: >-
      extracellular region reflects secretory or extracellular detection/pathway context for PRDX4 rather
      than the main site of its curated peroxidase function.
    action: KEEP_AS_NON_CORE
    reason: >-
      PRDX4 is an ER/secretory-pathway peroxiredoxin, so extracellular or granule-lumen pathway placements
      can be retained as non-core context while ER remains the primary location.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        PRDX4 is cotranslationally translocated to and retained within the endoplasmic reticulum.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report notes PRDX4 can be secreted/extracellular and has been detected in extracellular
        vesicle datasets, supporting non-core secretory/extracellular context.
- term:
    id: GO:0005576
    label: extracellular region
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-6800434
  review:
    summary: >-
      extracellular region reflects secretory or extracellular detection/pathway context for PRDX4 rather
      than the main site of its curated peroxidase function.
    action: KEEP_AS_NON_CORE
    reason: >-
      PRDX4 is an ER/secretory-pathway peroxiredoxin, so extracellular or granule-lumen pathway placements
      can be retained as non-core context while ER remains the primary location.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        PRDX4 is cotranslationally translocated to and retained within the endoplasmic reticulum.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report notes PRDX4 can be secreted/extracellular and has been detected in extracellular
        vesicle datasets, supporting non-core secretory/extracellular context.
- term:
    id: GO:0034774
    label: secretory granule lumen
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-6798748
  review:
    summary: >-
      secretory granule lumen reflects secretory or extracellular detection/pathway context for PRDX4
      rather than the main site of its curated peroxidase function.
    action: KEEP_AS_NON_CORE
    reason: >-
      PRDX4 is an ER/secretory-pathway peroxiredoxin, so extracellular or granule-lumen pathway placements
      can be retained as non-core context while ER remains the primary location.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        PRDX4 is cotranslationally translocated to and retained within the endoplasmic reticulum.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report notes PRDX4 can be secreted/extracellular and has been detected in extracellular
        vesicle datasets, supporting non-core secretory/extracellular context.
- term:
    id: GO:1904813
    label: ficolin-1-rich granule lumen
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-6800434
  review:
    summary: >-
      ficolin-1-rich granule lumen reflects secretory or extracellular detection/pathway context for PRDX4
      rather than the main site of its curated peroxidase function.
    action: KEEP_AS_NON_CORE
    reason: >-
      PRDX4 is an ER/secretory-pathway peroxiredoxin, so extracellular or granule-lumen pathway placements
      can be retained as non-core context while ER remains the primary location.
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        PRDX4 is cotranslationally translocated to and retained within the endoplasmic reticulum.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report notes PRDX4 can be secreted/extracellular and has been detected in extracellular
        vesicle datasets, supporting non-core secretory/extracellular context.
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: HDA
  original_reference_id: PMID:21630459
  review:
    summary: >-
      nucleus comes from high-throughput proteomic detection and is not the main functional location of
      PRDX4.
    action: KEEP_AS_NON_CORE
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        The curated subcellular location is cytoplasm and endoplasmic reticulum, with ER retention noted
        as the main localization.
    reason: >-
      Retain the observation as non-core because proteomic localization can reflect cargo or context-specific
      detection. It should not displace the ER/cytoplasmic peroxiredoxin localization.
- term:
    id: GO:0070062
    label: extracellular exosome
  evidence_type: HDA
  original_reference_id: PMID:19199708
  review:
    summary: >-
      extracellular exosome comes from high-throughput proteomic detection and is not the main functional
      location of PRDX4.
    action: KEEP_AS_NON_CORE
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        The curated subcellular location is cytoplasm and endoplasmic reticulum, with ER retention noted
        as the main localization.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report notes PRDX4 can be secreted/extracellular and has been detected in extracellular
        vesicle datasets, supporting non-core secretory/extracellular context.
    reason: >-
      Retain the observation as non-core because proteomic localization can reflect cargo or context-specific
      detection. It should not displace the ER/cytoplasmic peroxiredoxin localization.
- term:
    id: GO:0007252
    label: I-kappaB phosphorylation
  evidence_type: TAS
  original_reference_id: PMID:9388242
  review:
    summary: >-
      PRDX4 modulates I-kappaB-alpha phosphorylation through redox regulation but is not the kinase that
      phosphorylates I-kappaB.
    action: MODIFY
    proposed_replacement_terms:
    - id: GO:1903719
      label: regulation of I-kappaB phosphorylation
    supported_by:
    - reference_id: PMID:9388242
      supporting_text: >-
        AOE372 defines a redox pathway that specifically regulates NF-kappaB activity via a modulation
        of IkappaB-alpha phosphorylation in the cytoplasm.
    reason: >-
      The evidence supports regulation of I-kappaB phosphorylation, not execution of phosphorylation.
      The annotation should be moved to a regulatory BP term.
- term:
    id: GO:0008379
    label: thioredoxin peroxidase activity
  evidence_type: TAS
  original_reference_id: PMID:9388242
  review:
    summary: >-
      thioredoxin peroxidase activity accurately captures PRDX4 catalysis as a thioredoxin-dependent 2-Cys
      peroxiredoxin that reduces hydroperoxides.
    action: ACCEPT
    supported_by:
    - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
      supporting_text: >-
        Reaction=a hydroperoxide + [thioredoxin]-dithiol = an alcohol + [thioredoxin]-disulfide + H2O;
        EC=1.11.1.24.
    - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
      supporting_text: >-
        Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and other hydroperoxides
        and supports ER redox/proteostasis biology.
    reason: >-
      This is the core molecular function of PRDX4 and is supported by both the original thioredoxin peroxidase
      study and structural/catalytic analysis.
references:
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO terms
  findings: []
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000043
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping
  findings: []
- id: GO_REF:0000052
  title: Gene Ontology annotation based on curation of immunofluorescence data
  findings: []
- id: GO_REF:0000107
  title: Automatic transfer of experimentally verified manual GO annotation data to orthologs using
    Ensembl Compara
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:17644091
  title: Peroxiredoxin-4 interacts with and regulates the thromboxane A(2) receptor.
  findings: []
- id: PMID:19199708
  title: Proteomic analysis of human parotid gland exosomes by multidimensional protein
    identification technology (MudPIT).
  findings: []
- id: PMID:21057456
  title: Recycling of peroxiredoxin IV provides a novel pathway for disulphide formation in the
    endoplasmic reticulum.
  findings: []
- id: PMID:21630459
  title: Proteomic characterization of the human sperm nucleus.
  findings: []
- id: PMID:21916849
  title: Structural insights into the peroxidase activity and inactivation of human peroxiredoxin 4.
  findings: []
- id: PMID:21988832
  title: Toward an understanding of the protein interaction network of the human liver.
  findings: []
- id: PMID:25959826
  title: Quantitative interaction proteomics of neurodegenerative disease proteins.
  findings: []
- id: PMID:32814053
  title: Interactome Mapping Provides a Network of Neurodegenerative Disease Proteins and Uncovers
    Widespread Protein Aggregation in Affected Brains.
  findings: []
- id: PMID:33961781
  title: Dual proteome-scale networks reveal cell-specific remodeling of the human interactome.
  findings: []
- id: PMID:9388242
  title: Regulatory role for a novel human thioredoxin peroxidase in NF-kappaB activation.
  findings: []
- id: Reactome:R-HSA-6798748
  title: Exocytosis of secretory granule lumen proteins
  findings: []
- id: Reactome:R-HSA-6800434
  title: Exocytosis of ficolin-rich granule lumen proteins
  findings: []
- id: file:human/PRDX4/PRDX4-uniprot.txt
  title: UniProt record for human PRDX4
  findings: []
- id: file:human/PRDX4/PRDX4-deep-research-falcon.md
  title: Falcon deep research on PRDX4 function
  findings:
  - statement: Falcon report identifies PRDX4 as ER-localized typical 2-Cys peroxiredoxin.
    supporting_text: >-
      PRDX4 catalyzes peroxide reduction through the canonical typical 2-Cys cycle
  - statement: Falcon report emphasizes ER luminal localization and secreted/extracellular context.
    supporting_text: >-
      PRDX4 is localized mainly to the endoplasmic reticulum
core_functions:
- description: >-
    Reduces hydrogen peroxide and organic hydroperoxides using thioredoxin, supporting peroxide detoxification
    and redox homeostasis primarily in the endoplasmic reticulum with a smaller cytoplasmic pool.
  molecular_function:
    id: GO:0140824
    label: thioredoxin-dependent peroxiredoxin activity
  directly_involved_in:
  - id: GO:0042744
    label: hydrogen peroxide catabolic process
  - id: GO:0045454
    label: cell redox homeostasis
  locations:
  - id: GO:0005783
    label: endoplasmic reticulum
  - id: GO:0005829
    label: cytosol
  substrates:
  - id: CHEBI:35924
    label: hydroperoxide
  supported_by:
  - reference_id: file:human/PRDX4/PRDX4-uniprot.txt
    supporting_text: >-
      Thiol-specific peroxidase that catalyzes the reduction of hydrogen peroxide and organic hydroperoxides
      to water and alcohols, respectively.
  - reference_id: file:human/PRDX4/PRDX4-deep-research-falcon.md
    supporting_text: >-
      Falcon report summarizes PRDX4 as a typical 2-Cys peroxiredoxin that reduces H2O2 and organic hydroperoxides
      and functions mainly in the ER lumen.
proposed_new_terms: []
suggested_questions:
- question: Which PRDX4 pools act in ER peroxide detoxification versus cytoplasmic NF-kappaB redox
    modulation?
  experts:
  - redox biologists
  - ER protein folding specialists
- question: Under which physiological conditions is PRDX4 secreted or detected in granule/exosome
    compartments?
  experts:
  - secretory pathway specialists
  - proteomics experts
suggested_experiments:
- experiment_type: Compartment-specific redox assay
  description: Measure ER and cytosolic peroxide handling after PRDX4 knockout and
    compartment-targeted rescue.
  hypothesis: ER-localized PRDX4 is the dominant contributor to ER peroxide detoxification while a
    smaller cytosolic pool affects NF-kappaB redox signaling.
- experiment_type: Oligomerization mutant analysis
  description: Test PRDX4 dimer/decamer interface mutants for peroxidase activity and overoxidation
    sensitivity in cells.
  hypothesis: PRDX4 oligomeric assembly is required for efficient thioredoxin-dependent peroxidase
    activity and controls susceptibility to overoxidation.

PRDX4

Gene Description

Existing Annotations Review

Core Functions

Reduces hydrogen peroxide and organic hydroperoxides using thioredoxin, supporting peroxide detoxification and redox homeostasis primarily in the endoplasmic reticulum with a smaller cytoplasmic pool.

References

Suggested Questions for Experts

Suggested Experiments

📚 Additional Documentation

Deep Research Falcon

Question

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

Target Gene/Protein Identity (from UniProt):

MANDATORY VERIFICATION STEPS:

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

Research Target:

Output

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

Target Gene/Protein Identity (from UniProt):

MANDATORY VERIFICATION STEPS:

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

Research Target:

Comprehensive Functional-Annotation Research Report: Human PRDX4 (Peroxiredoxin-4; UniProt Q13162)

0) Target identity verification (critical disambiguation)

1) Key concepts and definitions (current understanding)

1.1 Peroxiredoxins and “typical 2-Cys” peroxiredoxins

1.2 What makes PRDX4 distinct among human PRDXs

2) Molecular function: enzymatic reaction, mechanism, and substrate specificity

2.1 Enzymatic activity and reaction chemistry

2.2 Electron donors and recycling partners (thioredoxin/PDI-linked redox systems)

2.3 Kinetics and quantitative enzymology

2.4 Hyperoxidation, inactivation, and functional switching (peroxidase ↔ chaperone)

3) Cellular localization and where PRDX4 acts

3.1 ER luminal targeting and retention versus secretion

3.2 Isoforms and compartment-specific implications

4) Pathways and biological processes: oxidative protein folding and ER redox homeostasis

4.1 Integration into oxidative folding pathways (ERO1–PDI axis and PRDX4)

4.2 ERO1-independent H2O2 supply and PRDX4-mediated folding

4.3 ER stress/UPR linkage: redox feedback loops that involve PRDX4

5) Recent developments and latest research (prioritizing 2023–2024)

5.1 2023: Systems-level framing of PRDX4 within ER stress and oxidative stress

5.2 2024: PRDX4 in cancer-redox discussions as a compensatory ER oxidoreductase

5.3 2024: PRDX4 detection in extracellular vesicles (real-world proteomics implementation)

6) Current applications and real-world implementations

6.1 Biomarker-oriented measurements in secreted/extracellular compartments

6.2 Targetable ER redox dependencies in cancer biology (expert synthesis)

7) Expert opinions and authoritative synthesis

7.1 PRDX4 as a node coupling peroxide detoxification to productive oxidative folding

7.2 PRDX4 in ER stress–oxidative stress feedback loops

8) Relevant statistics and data highlights (from recent and foundational sources)

9) Summary functional annotation (actionable for gene/protein annotation)

Embedded evidence summary table

Key figures (mechanism and isoform schematic)

References (URLs and publication dates)

Citations

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