ETFDH direct experimental sources

ETFDH accepts electrons from reduced electron-transfer flavoprotein and reduces ubiquinone. The experiments below distinguish this membrane-associated quinone reductase from the soluble ETFA–ETFB carrier. The human long precursor, recombinant host, native porcine structure and current shorter product are kept separate.

Human enzyme chemistry and localization

• PMID:8306995, original article. Actual publisher-indexed original pages were read despite direct PDF access failures: Methods p. 280, Results pp. 283–284 and Figures 6–10 captions. The human 617-residue precursor was expressed in yeast after untranslated-sequence and codon-usage changes. Mitochondrial fractionation, active submitochondrial extracts and processing support the imported activity/location assertions. The succinate-to-ETF experiment through endogenous ubiquinone is reported as data not shown. Early membrane-spanning predictions are not adopted. This was partial original access, without figure-pixel inspection.
• PMID:12049629, journal DOI, actual author-uploaded original. Read Methods pp. 660–661, Results pp. 662–664 and the relevant Discussion pp. 665–666. Human precursor expressed in Sf9 cells yielded processed enzyme with ETF-dependent quinone reduction and cofactor spectra. Its exact inner-membrane localization was inferred in this paper; the independent 1994 experiments supply more precise localization evidence. The apparent recombinant dimer is not treated as universal native oligomerization.
• PMID:14640977, journal DOI, actual author-uploaded manuscript. Read the Immediate Publication manuscript dated 26 November 2003, distinguishing it from the final 2004 version. The enzyme-preparation/assay Methods and substrate-kinetic Results, Figures 2–3 captions and fluorescence-binding Methods support human ETFDH quinone reduction and binding. Menadione, duroquinone and DBMIB provide positive broader quinone evidence; their in-vitro behavior does not establish new physiological substrates. No figure pixels or supplements were inspected.

The tested coupled reaction passes electrons from octanoyl-CoA through MCAD and ETF to quinone. ETFDH performs the terminal redox step in that assay; it is not itself an acyl-CoA dehydrogenase or proton pump. This supports respiratory electron-transport and acyl-CoA-dehydrogenase beta-oxidation participation without claiming complete respiratory flux was reconstituted.

Cofactors and disease evidence

• PMID:17050691, actual full original, DOI. Main Results, Discussion, Methods and captions were read. The crystal structure is native porcine liver ETFDH, P55931, with FAD, a 4Fe–4S cluster and ubiquinone. It supports a monotopic membrane-interaction model. It is not a human structure; mature-chain numbering and older proposed redox-center routing must not be transferred automatically.
• PMID:18037314, actual full original, DOI. Read preparation/EPR Methods sections 2.1–2.4, Table 1 and target-relevant Results/Table 3. The human Sf9-derived preparation has direct iron–sulfur and FAD-semiquinone evidence. Porcine and bacterial preparations are separately identified. Later specialized signal-analysis Methods were not comprehensively reviewed; no figure pixels or supplements were inspected.
• PMID:17412732, actual full original, DOI. Read respiratory-chain/CoQ/acylcarnitine/genetic Methods, relevant patient Results and Discussion. Human variants, muscle lipid storage and acylcarnitine abnormalities support ETFDH-associated disease. Purified-enzyme chemistry comes from the independent human studies above. Secondary CoQ deficiency does not establish ETFDH-catalyzed CoQ biosynthesis. Earlier individual clinical histories were not read in their entirety, and no figure pixels were inspected.

Target-specific screen evidence

PMID:32296183, original, official HuRI data. The main screen-generation/verification Methods and Results and all 21 exact ETFDH PSI records were read. Human ETFDH ORF 7047 is paired with the following archived human ORFs, tested in yeast. Each pair has three method records, including a validated two-hybrid record. These assays support associations; they do not by themselves identify a core catalytic/adaptor role or an endogenous mitochondrial complex. Random-subset orthogonal validation is not attributed to these individual pairs.

The MYH7B partner is archived as A0A087X0T3. Its stable Ensembl gene bridges to current A7E2Y1, but the archived UniParc sequence is 1,982 residues and current A7E2Y1-2 is 176 residues. The imported partner is retained literally and the positive gene-level association is retained; current-product equivalence is not asserted. Other archived ORFs likewise have no newly verified exact-current-sequence claim.

PMID:34800366, original. Read the target-relevant main Results and experimental Methods, plus actual supplementary spreadsheets. ETFDH protein group 6390 is in Table S1 (mmc2), sheet A row 351 and sheet B row 317. Table S2 (mmc3) has subtractive-proteomics row 3659 and spatial-proteomics row 4010. Table S3 (mmc4) has TOMM40-importomics row 3105 and carbonate/sonication row 315. These are positive mitochondrial and membrane-associated measurements. The table’s preexisting inner-membrane annotation is not treated as a new assay; more precise location uses the independent human-expression experiments. Some protein groups contain both Q16134 and Q16134-3, so these measurements do not independently demonstrate both products. No figure pixels were inspected.

Product and ontology boundaries

The two preserved source-described products are Q16134-1 (617 residues) and Q16134-3 (570 residues). The latter deletes residues 12–58, overlapping the annotated targeting region. No equal processing, localization or catalytic activity is inferred. Historical constructs are identified by their reported sequence/host; no blanket sequence equivalence is manufactured.

Current official QuickGO definitions and separately typed ancestor queries support the refinements to GO:0004174, GO:0022904 and GO:0005743. The specific activity is an electron-transfer/oxidoreductase descendant and participates in respiratory electron transport. Broader quinone binding is retained because additional quinones were genuinely tested, alongside the supported ubiquinone-binding assertion.

Normal publication caches remain unchanged. Genuine GOA and UniProt refreshes are separately compared with their fixed-main preimages and proposed as machine inputs; neither version was hand-edited. Access descriptions above refer to separately recovered originals, not to rewritten normal-cache flags. Reference review overlays record this access explicitly. PMID:8306995 retains full_text_unavailable: true because only the listed original pages were recovered; that access limit does not negate the operative evidence on those pages. No new publication quotations or new annotation assertions are proposed.

Database provenance and oxidative-stress transfer

PMID:17023274, original publisher preview is the verified mouse Q921G7 IDA source for both human oxidative-stress transfers. The abstract and limited indexed Materials/Results/Discussion identify carbonylated cardiac ETF-QO after adriamycin. Complete operative Methods/Results, Table 1 and figure pixels remain unavailable. Being oxidatively modified does not itself establish performing an oxidative-stress response step; the incomplete source supports uncertainty rather than rejection of the experimental annotation. The normal publication record was genuinely fetched and retains its abstract-only metadata.

The actual PANTHER PTHR10617 tree and alignment place human leaf PTN002472061 below PTN000835262 and PTN000065332. Its ungapped sequence exactly matches canonical human Q16134. The three positive IBD assertions and current donor sets match the captured GOA contexts; no target-path NOT assertion was found. Human self-WITH is legitimate experimental descendant evidence. Neither donor count nor failed donor-query prefixes are used to judge the node placement.

IPR040156 matches the target family and carries the activity/electron-chain mappings. IPR007859 matches the iron-sulfur-binding region. The actual ARBA00026962 rule has two matching disjuncts for Q16134: zero-based condition sets 23 and 79. The broad mitochondrial output is valid; independent target evidence supports refinement to the inner membrane. The EC 1.5.5.1 entry and Rhea 24052 reaction specify ETF oxidation coupled to ubiquinone reduction. Rhea's direct pages failed during acquisition; its official SPARQL response supplied the equation and links.

Reactome R-HSA-169270 explicitly identifies catalyst activity 169271, physical entity 448210 and human reference entity 405899/Q16134. The modeled target has coordinates 34–617 and its own mitochondrial inner-membrane compartment. Reduced ETF 169268 and oxidized ETF 169267 are separate carriers. R-HSA-611105 contains that reaction. This executed catalytic step supports respiratory-chain participation without assigning proton pumping or ATP synthesis to ETFDH.

The HPA target record and selected HEK293 image support mitochondria, not inner-membrane optical resolution. HPA058140's antigen matches canonical residues 206–299 and alternative-product residues 159–252. The assay therefore does not distinguish the products. OE19's additional nucleoplasm/cytosol signals remain acknowledged; those cells' images were not inspected. Inner-membrane specificity comes independently from the target Reactome participant, SL-0168 and human-protein import/biochemistry.

Current GO:0005743, GO:0022904 and GO:0051539 definitions and ancestry support the location, respiratory-chain and 4Fe–4S refinements respectively. GO:0006979 describes a response process; the unresolved issue is ETFDH's role in that process, not absence of the mouse source annotation.

Core synthesis and preserved facets

The primary molecular activity is GO:0004174, the ETF-to-ubiquinone redox reaction. The ubiquinone, FAD and 4Fe–4S binding slots describe its substrate/cofactor facets. The final slot describes that same activity within the acyl-CoA-dehydrogenase branch of beta-oxidation, whose current GO:0033539 definition includes passage of the removed electrons through the respiratory chain. Human coupled enzymology supplies this executed step; patient phenotypes are complementary context.

For PMID:14640977, the human quinone-binding interpretation uses the actual author-uploaded Immediate Publication manuscript: purification/assay Methods, fluorescence titration Methods and Results concerning alternative substrates, DBMIB binding and the single-site interpretation. The fluorescence ligand is DBMIB, not an independently measured affinity for every native ubiquinone species. The porcine structure supplies the resolved native-quinone site. No new affinity value, obligatory redox routing, native oligomeric state or physiological alternative substrate is inferred. No figure pixels or supplements were newly inspected during synthesis.

No process term or annotation row was newly asserted. Current authoritative definitions/branches were checked for all seven distinct core terms. The five slot positions and inherited supporting-text/reference prefixes were preserved, and additional support consists only of bare references already present in the review.