FDXR

Summary: FDXR catalyzes electron transfer between NADP(H) and ferredoxin.

Reason: The GO definition specifies the reversible ferredoxin/NADP redox reaction. Human target enzyme evidence is independently represented by PMID:2845396, and PMID:38425362 provides reconstitution with reconstructed tetrapod-ancestral FDXR/FDX2 rather than extant human proteins. The actual target UniProt catalytic entries and Reactome FDXR catalyst agree. Retain the phylogenetic assertion with its unreplayed placement limitation. Exact PAINT placement remains unavailable; the family-version, download and self-WITH limits are retained in FDXR-database-source-guide.md and FDXR-phylogeny-evidence.yaml.

Summary: FDXR supplies NADPH-derived electrons to ferredoxin; ancestral reconstitution directly resolves this catalytic role.

Reason: PMID:38425362 Results, C5 transformation requires a ferredoxin couple, and Extended Data Figure 3 show FDXR reduction followed by FDX2-dependent reoxidation, NADPH turnover, and coupled electron transfer. The assayed FDXR and FDX2 are reconstructed tetrapod ancestors, not extant human proteins. This supports the conserved reductase function; the human assignment is also consistent with the fully read human cDNA study PMID:2845396 and the established enzyme identity. Retain the gene-level function without calling the ancestral preparation a human direct assay or assigning the measurements to all seven human splice products. The evidence-code concern is separately recorded as a PROBABLE source-level CHECK request, not an established ISS correction.

Summary: The combined electronic inference matches FDXR ferredoxin reductase chemistry.

Reason: The actual ARBA00095261 rule predicts GO:0004324 from a Metazoa/FunFam 3.50.50.60:FF:000036 condition set. The target has the corresponding Gene3D superfamily, but exact FunFam matching and historical rule execution were not replayed. RHEA:20125 appears in both the official target catalytic entry and the exact GO definition. The standalone Rhea reaction-file endpoint returned HTTP 403; its file was not read as chemistry. Concordant target enzyme and reaction-model evidence supports the term. GO_REF:0000120 combines identical electronic predictions and does not add independent experimental replication.

Summary: Human FDXR is the NADPH-dependent reductase of the mitochondrial ferredoxin electron-transfer system.

Reason: The complete original PMID:2845396 identifies human adrenal and testicular adrenodoxin reductase cDNAs and explicitly describes electron transfer from NADPH through FDXR and adrenodoxin to mitochondrial P450scc (page 7104). This supports the traceable author statement. Its original experiments characterize sequences, alternative splicing, gene location and RNA expression; they do not measure catalytic differences between the two splice forms. The conserved catalytic role is independently resolved in the ancestral FDXR/FDX2 reconstitution in PMID:38425362. The GO reaction is reversible notation and is consistent with physiological NADPH oxidation coupled to ferredoxin reduction.

Summary: Reactome assigns the ferredoxin reductase activity to FDXR itself.

Reason: Actual event 2395512 has catalystActivity 9954152, whose physicalEntity 2395499 is human FDXR, referenceEntity 49738/P22570, residues 33–491 in mitochondrial matrix. Its activity is exactly GO:0004324. FDXR:FADH2 donates electrons to FDX1/FDX2, with oxidized FDXR:FAD produced. The two events represent the coupled catalytic cycle, not evidence that the isolated half-reaction alone is the complete GO reaction. The source is a pathway model, not a new direct assay.

Summary: Reactome assigns the ferredoxin reductase activity to FDXR itself.

Reason: Actual event 2395517 has catalystActivity 9954152, whose physicalEntity 2395499 is human FDXR, referenceEntity 49738/P22570, residues 33–491 in mitochondrial matrix. Its activity is exactly GO:0004324. NADPH reduces the FAD moiety of FDXR; this is one half-reaction of the overall ferredoxin reductase cycle. The two events represent the coupled catalytic cycle, not evidence that the isolated half-reaction alone is the complete GO reaction. The source is a pathway model, not a new direct assay.

Summary: FDXR is included in the human mitochondrial proteome and shows mitochondrial enrichment in the exact target dataset.

Reason: The original MitoCoP Table S1 workbook, sheet B row 343, names FDXR and P22570 and marks MitoCoP membership. Table S2 sheet G row 3234 joins the P22570-containing protein group to FDXR and positive mitochondrial clusters in HEK, HeLa, Huh7 and U2OS cells, with positive normalized pure/crude mitochondrial ratios. The group includes multiple FDXR isoform accessions and does not separately establish every splice product. The study combines experimental enrichment and curated prior knowledge; the Table S1 membership flag alone is not treated as a new localization experiment. These exact target data support mitochondrion without establishing a submitochondrial compartment or exclusive localization.

Summary: FDXR has a conserved mitochondrial pool.

Reason: Actual human HPA antibody observations, target UniProt localization evidence and the source-specific human localization evidence represented by PMID:29040572 support this organelle claim. The root organelle remains informative under the organelle policy even when matrix or inner-membrane annotations are retained. This positive mitochondrial claim is not exclusive or universal across products. PMID:41511346 Figure 1H places tagged paper isoform 7 (UniProt P22570-4) predominantly in the cytosol, unlike paper 1/4; the exact reversed 4/7 numbering, MCF7 assay and processing limits are retained in FDXR-isoform-source-joins.yaml and FDXR-database-source-guide.md. Exact PAINT placement remains unavailable; the family-version, download and self-WITH limits are retained in FDXR-database-source-guide.md and FDXR-phylogeny-evidence.yaml.

Summary: HPA supports mitochondrial FDXR localization.

Reason: Actual HPA ICC/IF records report supported U2OS mitochondria with CAB008597 and enhanced A-549, Hep-G2 and U2OS mitochondria with HPA044393 and HPA053673. HPA044393 also supports the iPSC mitochondrial call; HPA053673 sperm images are reported as no positivity, a distinct context. The two HPA antigens match canonical residues 1–134 and 372–464. Three selected original somatic-cell composite images were viewed and show a mitochondrial-type reticular/punctate signal. They do not independently resolve matrix versus inner membrane, prove exclusive localization, or distinguish every splice product; the composite channels are target, nucleus and microtubules, not a dedicated mitochondrial co-stain. The actual assay supports the informative root organelle term and is not refined to an unresolved submitochondrial compartment.

Summary: Endogenous human FDXR overlaps the mitochondrial marker in control and patient fibroblasts.

Reason: PMID:29040572 Results and Figure 2C–D directly report FDXR immunofluorescence overlapping MitoTracker in human control and patient fibroblasts; the Methods describe the paired staining and confocal imaging. The same Results explicitly acknowledge additional nuclear and cytoplasmic signal, so this positive mitochondrial annotation is not an exclusivity claim. The mitochondrial-matrix statement in that paragraph is attributed to earlier work, rather than measured by the confocal experiment. PMID:29554255 corrects three family genotype labels in Figure 1, not the Figure 2 localization result.

Summary: The UniProt location mapping retains a supported mitochondrial pool.

Reason: The actual human UniProt record contains SL-0173 with experimental provenance to PMID:29040572. This agrees with the HPA observations and the bounded tagged-isoform evidence. The electronic mapping does not create another independent assay. This positive mitochondrial claim is not exclusive or universal across products. PMID:41511346 Figure 1H places tagged paper isoform 7 (UniProt P22570-4) predominantly in the cytosol, unlike paper 1/4; the exact reversed 4/7 numbering, MCF7 assay and processing limits are retained in FDXR-isoform-source-joins.yaml and FDXR-database-source-guide.md.

Summary: The mitochondrial location of human adrenodoxin reductase is supported as a traceable author statement.

Reason: The complete original PMID:2845396 describes adrenodoxin reductase as a mitochondrial flavoprotein, places its electron-transfer function in the mitochondrial P450 system, and depicts a precursor targeting segment (pages 7104–7106). It does not perform a new microscopy localization assay. Independent human fibroblast imaging in PMID:29040572 and exact FDXR mitochondrial enrichment in PMID:34800366 corroborate the organelle-level claim. No exclusive location or function for every splice form is inferred.

Summary: Inner-membrane association is retained as a curated cross-species inference.

Reason: The UniProt SL mapping derives inner-membrane localization from the yeast donor P48360. Positive donor fractionation with compartment controls and conserved reductase function support the curated inference. It is not a direct human submitochondrial assay, a transmembrane-helix assertion, exclusive residence, or a location for every splice product. FDXR-database-source-guide.md retains antiserum controls and the non-independent bovine donor chain.

Summary: Inner-membrane association is retained as a curated cross-species inference.

Reason: The ISS supporting entity P48360 is yeast Arh1, whose endogenous antigen co-fractionates with inner membrane in PMID:9727014 Figure 7. Positive donor fractionation with compartment controls and conserved reductase function support the curated inference. It is not a direct human submitochondrial assay, a transmembrane-helix assertion, exclusive residence, or a location for every splice product. FDXR-database-source-guide.md retains antiserum controls and the non-independent bovine donor chain.

Summary: The Reactome event contains a genuine matrix-localized FDXR entity.

Reason: The actual nested route is 193054 catalystActivity 193154; 193154 physicalEntity 5580249; 5580249 hasComponent 2395499. It reaches human entity 2395499, referenceEntity 49738/P22570, modeled residues 33–491 and GO:0005759 mitochondrial matrix. FDXR is a component of the CYP11A1 redox assembly; CYP11A1 performs cholesterol oxidation/cleavage. This is a curated compartment assertion; the human-assay, peripheral-membrane and product-processing limits are retained once in FDXR-database-source-guide.md.

Summary: The Reactome event contains a genuine matrix-localized FDXR entity.

Reason: The actual nested route is 193065 catalystActivity 193154; 193154 physicalEntity 5580249; 5580249 hasComponent 2395499. It reaches human entity 2395499, referenceEntity 49738/P22570, modeled residues 33–491 and GO:0005759 mitochondrial matrix. FDXR is a component of the CYP11A1 redox assembly; CYP11A1 performs cholesterol oxidation/cleavage. This is a curated compartment assertion; the human-assay, peripheral-membrane and product-processing limits are retained once in FDXR-database-source-guide.md.

Summary: The Reactome event contains a genuine matrix-localized FDXR entity.

Reason: The actual nested route is 193101 input 5580249; 5580249 hasComponent 2395499. It reaches human entity 2395499, referenceEntity 49738/P22570, modeled residues 33–491 and GO:0005759 mitochondrial matrix. FDXR is a component of the CYP11A1 redox assembly; CYP11A1 performs cholesterol oxidation/cleavage. This is a curated compartment assertion; the human-assay, peripheral-membrane and product-processing limits are retained once in FDXR-database-source-guide.md.

Summary: The Reactome event contains a genuine matrix-localized FDXR entity.

Reason: The actual nested route is 2395512 input 2395502; 2395502 hasComponent 2395499. It reaches human entity 2395499, referenceEntity 49738/P22570, modeled residues 33–491 and GO:0005759 mitochondrial matrix. FDXR participates directly in the NADPH-to-ferredoxin electron-transfer cycle. This is a curated compartment assertion; the human-assay, peripheral-membrane and product-processing limits are retained once in FDXR-database-source-guide.md.

Summary: The Reactome event contains a genuine matrix-localized FDXR entity.

Reason: The actual nested route is 2395517 input 2395508; 2395508 hasComponent 2395499. It reaches human entity 2395499, referenceEntity 49738/P22570, modeled residues 33–491 and GO:0005759 mitochondrial matrix. FDXR participates directly in the NADPH-to-ferredoxin electron-transfer cycle. This is a curated compartment assertion; the human-assay, peripheral-membrane and product-processing limits are retained once in FDXR-database-source-guide.md.

Summary: The Reactome event contains a genuine matrix-localized FDXR entity.

Reason: The actual nested route is 5580269 input 9013350; 9013350 hasComponent 2395499. It reaches human entity 2395499, referenceEntity 49738/P22570, modeled residues 33–491 and GO:0005759 mitochondrial matrix. The event models defective CYP11A1; FDXR is a normal nested partner, not the defective enzyme or cholesterol-cleavage catalyst. This is a curated compartment assertion; the human-assay, peripheral-membrane and product-processing limits are retained once in FDXR-database-source-guide.md.

Summary: Broad precursor and energy metabolism is retained as context for FDXR electron supply, rather than a defining core process.

Reason: PMID:2845396 describes FDXR supplying electrons through adrenodoxin to the mitochondrial P450 reactions that convert cholesterol to pregnenolone and other metabolites. This is an actual catalytic contribution, not only a loss-of-function requirement, but the broad term is less informative than the resolved reductase role and its pathway contexts. It does not mean that FDXR itself generates ATP or is an oxidative-phosphorylation complex subunit. The verified ontology does not place the existing steroid or ubiquinone biosynthetic terms beneath GO:0006091, so a redundancy-based TOO_GENERAL action would not be justified by either of those annotations. Retain the curator-supported broad metabolic context as non-core. The saved official QuickGO is_a/part_of ancestor response for GO:0006744 lists 12 identifiers including itself, with neither GO:0006091 nor the suggested intermediary GO:0006733. The steroid term GO:0006694 also lacks GO:0006091 in that response; the exact query and snapshot limits are given in FDXR-direct-source-guide.md.

Summary: FDXR directly changes the redox state of ferredoxin.

Reason: GO:0006124 covers chemical reactions involving ferredoxin; it is not limited to synthesis or degradation of the ferredoxin polypeptide. Actual Reactome pathway 2395516 contains events 2395517 and 2395512, tracing NADPH reduction of FDXR and subsequent reduction of FDX1/FDX2. FDXR catalyzes the electron-transfer step and therefore participates, rather than merely being a substrate or a necessary upstream gene. The pathway label does not imply mitochondrial respiratory-chain membership.

Summary: FDXR supplies reducing equivalents to steroid-biosynthetic enzymes.

Reason: The conserved role is an actual electron-transfer contribution to steroidogenic chemistry, not a disease or developmental phenotype alone. The GOA descendant FB:FBgn0015582 is verified as Drosophila dare; its steroid-process annotations trace to the Freeman study. Only the original abstract/first-page preview was read for that donor, so no uninspected fly assay detail is claimed. Human target expression/activity provenance and actual Reactome CYP11A1 redox-assembly membership independently support the steroid-biosynthetic role. Exact PAINT placement remains unavailable; the family-version, download and self-WITH limits are retained in FDXR-database-source-guide.md and FDXR-phylogeny-evidence.yaml.

Summary: FDXR participates in steroid biosynthesis by supplying reducing equivalents to the mitochondrial P450 system.

Reason: The verified PMID:1863359 abstract explicitly places adrenodoxin reductase upstream of adrenodoxin and P450scc in human steroidogenesis. Its own reported study is regional gene mapping; full text remained inaccessible after a publisher attempt. The same gene-level biochemical contribution is independently stated in the fully read original PMID:2845396, page 7104: FDXR performs electron transfer from NADPH through adrenodoxin to the P450scc reactions that form pregnenolone. Retain the TAS claim on that matching positive evidence and curator judgment, without inventing a steroid-conversion assay in the mapping study or assigning P450 cleavage chemistry to FDXR. Independent PMID:38885337 adds human patient-derived adrenal-like cell steroid-output measurements and male mutant-mouse serum profiles. These corroborate pathway impairment but do not directly reconstitute purified FDXR-dependent CYP chemistry; altered mitochondrial redox balance can also contribute.

Summary: FDXR provides catalytic reducing equivalents for COQ6-dependent ubiquinone biosynthesis.

Reason: PMID:38425362 Results and Figures 2 and 4 resolve the NADPH–FDXR–FDX2 electron supply to COQ6: coupled reduction accompanies C5 hydroxylation, substrate product is detected by mass spectrometry, and conversion is absent without the ferredoxin pair. The corresponding C1 hydroxylation also uses this electron supply. FDXR therefore performs part of the biosynthetic work rather than merely being necessary for a phenotype. The proteins are reconstructed tetrapod ancestors and the reactions use short-chain CoQ intermediates; retaining the human gene-level claim relies on conserved enzyme function and the curated transfer, not a purported extant-human cellular experiment. No natural human isoform-specific CoQ activity or stable metabolon membership is established. The ACCEPT action retains the biological gene-level claim; it does not endorse the imported acts_upstream_of_positive_effect relation as a complete description of pathway participation. The unchanged source relation is less specific about participation than cached GO-CAM 675b862c00001470 activity 675b862c00001526: FDXR GO:0004324 is part_of GO:0006744 and directly_positively_regulates FDX2 activity 675b862c00001519. That curated model corroborates the core directly_involved_in synthesis from the electron-transfer assays; it is not independent experimental replication. Evidence-code representation remains a PROBABLE curator CHECK request.

Summary: FDXR participates in cholesterol metabolism as a redox partner.

Reason: The actual target UniProt pathway field is Steroid metabolism; cholesterol metabolism, with UPA00296 mapping to GO:0008203. The official GO_REF method states that UniPathway is archived and last released in 2015; archival status alone does not make this biology false. Actual Reactome cholesterol-to-pregnenolone steps include FDXR in the redox assembly. FDXR supplies electrons through ferredoxin, whereas CYP11A1 oxidizes and cleaves cholesterol. The broad metabolic process usefully covers the substrate/pathway dimension and is not asserted to be de novo cholesterol synthesis.

Summary: Generic oxidoreductase activity is covered by the retained ferredoxin reductase activity.

Reason: Actual target InterPro hits IPR021163 (Ferredoxin-NADP+ reductase, adrenodoxin-type; residues 34–489) and IPR055275 (Ferredoxin-NADP reductase-like; residues 34–487) both map to GO:0016491. Official typed is_a/part_of ancestry places the accepted GO:0004324 under this term. The generic activity is true but adds no resolved chemistry beyond that specific retained activity. PTHR48467 is a genuine current member family with the surprising official label GLUTAMATE SYNTHASE 1 [NADH], CHLOROPLASTIC-LIKE; that label is not interpreted as human FDXR glutamate-synthase activity.