DGUOK

Summary: Ancestral deoxyadenosine kinase activity is supported in human DGUOK.

Reason: The actual PTHR10513 tree places Q16854 below PTN002236991, where PAINT assigned the deoxyadenosine kinase IBD. Q16854 is legitimately among the experimental descendants used to place that assertion. Recombinant human enzyme experiments and radiochemical assays of human mitochondria-enriched fibroblast preparations independently support ATP-dependent dA phosphorylation. This is a major substrate activity of the mitochondrial salvage enzyme.

Summary: Low deoxycytidine phosphorylation is a secondary substrate activity.

Reason: Q16854 descends from the actual PTN002236991 deoxycytidine-kinase IBD; the presence of DCK relatives among its experimental descendants is not evidence of a misplaced transfer. PMID:8692979 Table 1 reports dCyd phosphorylation at about 0.1 relative to dGuo at both 5 and 100 micromolar substrate. Its competition experiment indicates low dCyd affinity, not zero activity. Retain the inherited catalytic capability as non-core because efficient purine salvage, rather than a demonstrated physiological dCyd-salvage role, is the established function.

Summary: The conserved deoxyguanosine kinase activity is directly supported in human DGUOK.

Reason: The target is descended from the PTN002236991 IBD and is one of the experimental descendants grounding that phylogenetic assertion. Recombinant human enzyme measurements, mitochondrial-enriched fibroblast assays and patient/control muscle assays establish dG phosphorylation. The valid target self-evidence is not circular propagation.

Summary: Refine the broad cytoplasmic placement to the mitochondrial matrix.

Reason: The PTN000053758 IBD lies on the actual Q16854 lineage. GO:0005737 includes cytoplasmic organelles, and mitochondrial matrix is within its typed ancestry; a mitochondrial protein is therefore not contrary evidence. The matrix localization stated in PMID:8706825 and explicitly represented for Q16854 in Reactome R-HSA-53573 provides the supported specific compartment for this salvage activity. This refinement does not assert cytosolic localization or exclude the separate sperm-nuclear observation.

Proposed replacements: mitochondrial matrix

Summary: Specify the matrix compartment of the mitochondrial salvage enzyme.

Reason: The actual mitochondrial IBD PTN002236975 is ancestral to Q16854 and is experimentally grounded. Its organelle-level placement is sound. Refine it using the independently supported matrix localization in PMID:8706825 and the Q16854 catalyst entity in Reactome; this does not imply that PAINT itself resolved a submitochondrial compartment.

Proposed replacements: mitochondrial matrix

Summary: The reaction mapping correctly identifies deoxyadenosine kinase activity.

Reason: The imported RHEA:23452/EC:2.7.1.76 mapping matches the official human DGUOK reaction and the measured ATP-dependent phosphorylation of deoxyadenosine. The human mitochondrial-enriched fibroblast assay explicitly suppresses cytosolic DCK interference with excess dC.

Summary: The reaction mapping correctly identifies deoxyguanosine kinase activity.

Reason: RHEA:19201 and EC:2.7.1.113 describe the DGUOK reaction converting deoxyguanosine and ATP to dGMP and ADP. Human recombinant and tissue-derived assays directly support this principal substrate activity.

Summary: ATP binding is an intrinsic part of the supported phosphotransfer chemistry.

Reason: The IPR002624 mapping is consistent with human DGUOK using ATP as phosphate donor. PMID:8692979 directly measures recombinant human enzyme phosphotransfer with labeled ATP and reports a conserved ATP-binding loop. GO:0005524 describes ATP binding; the deoxyguanosine and deoxyadenosine kinase terms lie in the catalytic branch and do not replace this distinct binding assertion. Retain ATP binding as part of the enzyme mechanism, without adding a separate physiological core.

Summary: Refine the valid UniProt organelle mapping to mitochondrial matrix.

Reason: The historical UniProt subcellular-location mapping correctly places DGUOK in mitochondria. PMID:8706825 and the human Q16854 Reactome catalyst provide the more precise matrix location. Preserve the original GO_REF:0000044 assertion and source dictionary even though a newer GOA release uses a different electronic reference for the organelle term.

Proposed replacements: mitochondrial matrix

Summary: Specify the two principal deoxynucleoside kinase activities.

Reason: The actual ARBA00033881 rule and InterPro IPR002624 record assign a valid family-level deoxynucleoside kinase activity. Human DGUOK assays resolve efficient deoxyguanosine and deoxyadenosine phosphorylation, so use those specific activities already represented in the source set. Low measured dCyd turnover is retained separately as non-core rather than denied.

Proposed replacements: deoxyguanosine kinase activity deoxyadenosine kinase activity

Summary: Refine broad carbohydrate-derivative metabolism to purine deoxyribonucleoside metabolism.

Reason: Deoxyribonucleosides contain a sugar moiety, so the broad ARBA process is not a contradiction. DGUOK performs a defined salvage step by phosphorylating purine deoxyribonucleosides; GO:0046122 describes that work more precisely. This term already exists in the review and adds no new process assertion.

Proposed replacements: purine deoxyribonucleoside metabolic process

Summary: The reported DCK association supports kinase binding.

Reason: Four positive IntAct records from PMID:33961781 identify human Q16854 and P27707/DCK, with both sequence/taxon identifiers matching the current canonical proteins. They include DCK-bait associations in HEK293T and HCT116 cells and the reciprocal DGUOK-bait association in HEK293T. The original methods use sequence-verified C-terminal FLAG-HA constructs and anti-HA affinity purification. DCK is a deoxynucleoside kinase, making GO:0019900 kinase binding the applicable partner class; GO:0019901 protein kinase binding would incorrectly imply a protein substrate. These co-complex measurements do not establish a purified binary interaction, a native mitochondrial heterodimer, or kinase activation.

Proposed replacements: kinase binding

Summary: The independent U2OS DCK association supports kinase binding.

Reason: The study-released U2OS AP-MS network contains the literal DCK-to-DGUOK edge 578496, with DCK marked as bait and DGUOK as prey. The actual methods describe sequence-validated C-terminal HA-Flag baits and filtered anti-HA AP-MS associations. DCK is a catalytic deoxynucleoside kinase, so GO:0019900 is more informative than protein binding without claiming protein-kinase binding. Preserve the association while keeping its co-complex and ectopic-expression limits; no DGUOK regulatory or native heterodimer function is inferred.

Proposed replacements: kinase binding

Summary: Retain the source-grounded neurite phenotype as a secondary context.

Reason: The exact rat Dguok donor D3ZDE4 carries RGD IMP evidence from PMID:18007665. The primary abstract explicitly identifies DGUOK among inhibitory neurite-screen hits, and supplementary legends S1/S2 document the human SH-SY5Y siRNA screen and neurite-length readout. GO:0010977 concerns reducing neurite development; it does not assert that DGUOK builds neurites or performs electron transfer. Retain this positive regulatory phenotype as a secondary context with curator deference for the rat transfer: validation of a subset in rat neurons is reported, but the DGUOK-specific rat panel was not independently recovered. A defined axonal signaling mechanism, direct cytoskeletal role and protein-kinase activity remain unestablished. This differs from GO:0042775, which specifically assigns execution of electron transfer rather than regulation of a developmental outcome.

Summary: DGUOK sustains respiratory capacity indirectly through nucleotide supply and mtDNA maintenance.

Reason: The exact D3ZDE4 donor has valid IMP evidence from PMID:30404003. Its original human knockout/rescue experiments and rat liver assays show that DGUOK loss reduces mtDNA-encoded respiratory proteins, oxygen consumption and ATP, with restoration by DGUOK expression or downstream interventions. DGUOK itself phosphorylates deoxynucleosides; the measured electron transport is performed by respiratory complexes. Thus the phenotype is real, but assigning execution of mitochondrial ATP synthesis coupled electron transport to the salvage kinase is mechanistically broader than demonstrated. This is an assessment of the process assignment, not a rejection of the source experiment or orthology. Unlike a negative-regulation term, GO:0042775 explicitly describes transfer of electrons between donors and acceptors; nucleotide-supply dependence alone does not establish that role.

Summary: Human mitochondrial-enriched preparations directly phosphorylate deoxyadenosine.

Reason: The recovered original Methods use radiolabeled dA, ATP/MgCl2 and mitochondria-enriched human fibroblast preparations, with 2 mM dC to suppress cytosolic DCK. Controls and DGUOK-mutant cells show the expected dAMP-forming activity and genotype-dependent reduction. This is direct support for dA kinase activity; the material is not purified recombinant enzyme and the variants are not natural short isoforms.

Summary: Recombinant human DGUOK phosphorylates deoxyadenosine.

Reason: The independently read original PMID:8692979 Table 1 measures dA phosphorylation by the expressed and cleaved human maltose-binding fusion. Relative activity rises with dA concentration. The historical 780-bp open reading frame is not equated to every modern UniProt product; the evidence establishes the gene-level substrate activity.

Summary: Recombinant human DGUOK has deoxyadenosine kinase activity.

Reason: The verified abstract reports purification of recombinant human enzyme and phosphorylation of deoxyadenosine as well as deoxyguanosine and deoxyinosine. Full methods were not recovered, so exact construct and kinetic details are not claimed from this reference. The activity is independently corroborated by the complete original 8692979 and human fibroblast assays.

Summary: Retain the curator-supported deoxyguanosine kinase activity.

Reason: The cached abstract foregrounds TK2 but explicitly recognizes mitochondrial dGK as a purine deoxynucleoside kinase. The full supporting assay was not recovered, so no claim of a DGUOK-specific experiment is reconstructed from this abstract. The function is directly established in independent human biochemical studies; defer to the experimental curator rather than infer paralog misattribution from the title.

Summary: Human mitochondrial-enriched preparations directly phosphorylate deoxyguanosine.

Reason: The recovered Methods and Results measure radiolabeled dG-to-dGMP conversion using ATP/MgCl2 in mitochondria-enriched human fibroblast preparations, including control and DGUOK-mutant samples. Excess dC suppresses cytosolic DCK interference. The assay and genotype dependence directly support the activity without requiring recombinant protein or a new isoform claim.

Summary: Patient/control muscle assays support deoxyguanosine kinase activity.

Reason: The recovered original Methods use radiolabeled dG and excess dC to exclude DCK interference. Muscle extracts from affected individuals retain 19–45% of control DGUOK activity after citrate-synthase normalization, with independent control enzymes arguing against poor specimen preservation. The disease alleles affect the established enzymatic activity; they are not equated to the six natural alternative products.

Summary: Refine the conserved mitochondrial placement using independent human matrix evidence.

Reason: The exact mouse donor Q9QX60 has an IDA mitochondrial annotation from PMID:10455141, whose abstract distinguishes full-length mitochondrial mouse dGK from an N-terminally truncated cytoplasmic mouse form. The donor is valid. Human DGUOK matrix localization is separately supported by PMID:8706825 and Reactome, allowing a specific replacement without transferring the mouse short-product localization to a human isoform.

Proposed replacements: mitochondrial matrix

Summary: Retain the mitochondrial proteomics evidence and specify matrix from independent sources.

Reason: The MitoCoP original combines subtractive and spatial proteomics, importomics and curated evidence across human cell lines. The imported DGUOK HTP assignment is consistent with direct mitochondrial-enriched human enzyme assays. The matrix refinement comes from PMID:8706825 and the explicit human Reactome catalyst, not an assertion that this proteomic study alone resolved the submitochondrial location.

Proposed replacements: mitochondrial matrix

Summary: Refine the established mitochondrial salvage location to matrix.

Reason: The source abstract describes human DGUOK-deficient myotubes and dAMP/dGMP supplementation, but its full localization assay was not recovered. Preserve curator deference for the valid mitochondrial placement, independently supported by human mitochondrial-enriched enzyme assays. The more precise matrix replacement is supported separately by PMID:8706825 and Reactome; it is not presented as imaging performed in this paper.

Proposed replacements: mitochondrial matrix

Summary: DGUOK directly performs the dAMP-producing salvage step.

Reason: The source abstract reports partial restoration of mtDNA after dAMP/dGMP supplementation in DGUOK-deficient human myotubes. That rescue alone demonstrates pathway dependence, while independent human enzyme assays establish the participation mechanism: DGUOK directly phosphorylates dA to dAMP. Retain this specific process annotation on the combined evidence, without treating supplementation as a purified enzymatic assay.

Summary: Retain DGUOK detection in isolated mature human sperm nuclei.

Reason: The author thesis explicitly identifies Appendix 8.2 as the protein catalogue supporting PMID:21630459; its Table 8.1 lists Q16854/DGUOK with 13.4% sequence coverage and two peptides (printed page 198). The paper abstract describes nuclei purified to over 99.9% with mitochondrial exclusion assessed microscopically. This supports the specialized proteomic observation and does not justify dismissing it as mitochondrial contamination. Keep it non-core: no nuclear enzymatic role, nuclear import mechanism or natural isoform identity was established.

Summary: Reactome explicitly places the human DGUOK catalyst in mitochondrial matrix.

Reason: The actual event R-HSA-74207 links catalyst activity 74206 to DGUOK dimer R-HSA-74205, whose component R-HSA-53573 is Q16854 residues 40–277 in mitochondrial matrix. The modeled reaction phosphorylates dA, dG or dI with ATP. This is an explicit target-specific curated location and reaction, not a pathway association inferred from a nearby protein.

Summary: Retain the experimentally curated deoxyguanosine kinase activity.

Reason: The verified source abstract describes recombinant human-enzyme purification and deoxyguanosine phosphorylation. The inaccessible full methods do not warrant rejecting this established activity; independent complete-original evidence and human mitochondrial-enriched preparations corroborate it.

Summary: Purine deoxyribonucleoside phosphorylation is direct pathway participation.

Reason: DGUOK catalyzes the conversion of purine deoxyribonucleosides to their monophosphates. It therefore performs the chemical work of the annotated metabolic process, rather than merely being required for a downstream phenotype. The source abstract and independent human substrate assays support the activity.

Summary: The original human expression study directly supports deoxyguanosine kinase activity.

Reason: The independently read full original reports recombinant human DGUOK and measures dGuo phosphorylation, with substrate comparisons and a radiophosphate-transfer assay. The preserved TAS source is biologically correct; the historical clone is not silently reassigned to every modern alternative product.

Summary: Specify matrix using the combined localization evidence.

Reason: The original PMID:8692979 predicts mitochondrial targeting from the N-terminal sequence and prior mitochondrial purification studies; it does not report a new DGUOK imaging experiment. Its mitochondrial conclusion is supported independently, and PMID:8706825 plus the human Reactome catalyst establish the more precise matrix location. Preserve the original source claim while making the combined basis of the refinement explicit.

Proposed replacements: mitochondrial matrix

Summary: Use the deoxyribonucleoside process matching the assayed substrates.

Reason: The original study assays deoxyguanosine, deoxyadenosine and deoxyinosine phosphorylation. The current GO:0008617 definition concerns guanosine/guanine riboside, whereas GO:0046122 explicitly covers purine deoxyribonucleoside metabolism and is already represented by source row 28. This corrects the substrate scope without asserting an unmeasured guanosine-ribonucleoside reaction.

Proposed replacements: purine deoxyribonucleoside metabolic process