ADA

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0004000 adenosine deaminase activity	IBA GO_REF:0000033	ACCEPT	Summary: Phylogenetic (IBA) inference of the defining molecular function of ADA, the hydrolytic deamination of adenosine to inosine. This is the core catalytic activity of the protein and is supported experimentally in human ADA. Reason: Core molecular function of ADA, conserved across the adenosine deaminase family and directly demonstrated for the human enzyme by catalytic-activity and biophysicochemical studies. Supporting Evidence: file:human/ADA/ADA-uniprot.txt Catalyzes the hydrolytic deamination of adenosine and 2- PMID:8452534 the conversion of [3H]adenosine into [3H]inosine was proportional to incubation time
GO:0005829 cytosol	IBA GO_REF:0000033	ACCEPT	Summary: Phylogenetic inference that ADA acts in the cytosol. ADA is predominantly a cytosolic enzyme, consistent with its role in intracellular purine catabolism. Reason: The cytosol is the primary site of ADA activity; UniProt and multiple Reactome/TAS annotations place the enzyme in the cytosol, and the cell-surface (ecto-ADA) pool is a secondary localization. Supporting Evidence: PMID:11772392 an enzyme mainly localized in the cytosol but also found on the cell surface of monocytes
GO:0042110 T cell activation	IBA GO_REF:0000033	KEEP AS NON CORE	Summary: Involvement in T cell activation, inferred phylogenetically and supported experimentally through the ecto-ADA/CD26 costimulatory axis on the T-cell surface. Reason: This is a genuine but moonlighting (extra-enzymatic / cell-surface) role of ADA, distinct from its core cytosolic catalytic function in purine catabolism. Cell-surface ADA bound to CD26 provides a costimulatory signal in T cell activation. Supporting Evidence: PMID:7594462 binding to CD26 produces a costimulatory response in T cell activation events
GO:0045187 regulation of circadian sleep/wake cycle, sleep	IBA GO_REF:0000033	KEEP AS NON CORE	Summary: Phylogenetic inference linking ADA to regulation of sleep. Adenosine is a well-established somnogen, and the common ADA2 (Asp8Asn) polymorphism, which lowers ADA activity, enhances deep sleep and slow-wave activity in humans. Reason:* A genuine physiological consequence of ADA controlling adenosine tone in the brain, but downstream of and secondary to the core catabolic activity rather than a defining molecular function. Supported by human polymorphism data. Supporting Evidence: file:human/ADA/ADA-uniprot.txt It specifically enhances deep sleep and slow-wave activity
GO:0006154 adenosine catabolic process	IBA GO_REF:0000033	ACCEPT	Summary: Phylogenetic inference that ADA participates in adenosine catabolism. This is the core biological process for ADA, the committed step converting adenosine to inosine in the purine degradation pathway. Reason: Adenosine catabolism is the defining biological role of ADA and is directly supported by its catalytic activity and by the phenotype of ADA-deficient cells, which accumulate the substrate (deoxy)adenosine. Supporting Evidence: file:human/ADA/ADA-uniprot.txt Plays an important role in purine PMID:9361033 the purine salvage enzyme adenosine deaminase
GO:0009897 external side of plasma membrane	IBA GO_REF:0000033	KEEP AS NON CORE	Summary: Phylogenetic inference that a pool of ADA is active on the external side of the plasma membrane (ecto-ADA), anchored via CD26/DPP4. This is corroborated by direct experimental localization in human cells. Reason: Ecto-ADA is a genuine second localization of the enzyme, but represents a moonlighting/cell-surface pool secondary to the predominant cytosolic activity. Supporting Evidence: PMID:16670267 ADA localizes to the endothelial surface and limits the accumulation of extracellular adenosine during hypoxia
GO:0060169 negative regulation of adenosine receptor signaling pathway	IBA GO_REF:0000033	KEEP AS NON CORE	Summary: Inference that ADA negatively regulates adenosine-receptor signaling. By catabolizing extracellular adenosine (the receptor agonist), ecto-ADA reduces adenosine-receptor activation; the net effect can be complex, since ADA can also allosterically enhance receptor agonist affinity. Reason: A real downstream signaling consequence of ADA's extracellular adenosine clearance, but secondary to the core catabolic activity rather than a defining molecular function. Note the effect is context-dependent (ADA also acts as a positive allosteric modulator of ADORA1/ADORA2A). Supporting Evidence: PMID:16670267 increasing the endothelial capacity to metabolize adenosine to inosine
GO:0043103 hypoxanthine salvage	IBA GO_REF:0000033	MARK AS OVER ANNOTATED	Summary: Phylogenetic inference associating ADA with hypoxanthine salvage. ADA produces inosine; hypoxanthine is generated downstream by purine nucleoside phosphorylase (PNP), not by ADA itself. Reason: ADA contributes to purine salvage upstream by generating inosine, but it does not catalyze any step producing or reutilizing hypoxanthine. Annotating ADA to hypoxanthine salvage over-extends the enzyme into a downstream pathway step carried out by other enzymes (PNP, HPRT). The upstream inosine-biosynthesis and adenosine-catabolism annotations already capture ADA's true contribution. Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH Sources checked: UniProtKB:P22333 · ADA family ortholog Family-level purine-salvage framing; ADA generates inosine but does not perform hypoxanthine salvage, which is downstream (PNP/HPRT).
GO:0046103 inosine biosynthetic process	IBA GO_REF:0000033	ACCEPT	Summary: Phylogenetic inference that ADA contributes to inosine biosynthesis. Inosine is the direct reaction product of adenosine deamination by ADA. Reason: ADA directly produces inosine from adenosine, so it is genuinely involved in inosine biosynthesis. This is a valid process-level annotation directly downstream of the core catalytic reaction. Supporting Evidence: PMID:8452534 the conversion of [3H]adenosine into [3H]inosine was proportional to incubation time
GO:0004000 adenosine deaminase activity	IEA GO_REF:0000120	ACCEPT	Summary: Electronic annotation (multiple IEA methods, incl. RHEA:24408 mapping) of the core adenosine deaminase activity. Duplicate of the experimentally and phylogenetically supported core MF. Reason: Correct core molecular function, consistent with the RHEA reaction and experimental catalytic-activity data. Supporting Evidence: file:human/ADA/ADA-uniprot.txt Catalyzes the hydrolytic deamination of adenosine and 2-
GO:0005737 cytoplasm	IEA GO_REF:0000120	KEEP AS NON CORE	Summary: Electronic localization to the cytoplasm. Consistent with ADA being a predominantly cytosolic enzyme, though cytosol (GO:0005829) is the more specific and better-supported term. Reason: Correct but less specific than the cytosol annotation. Retained as accurate but non-core relative to the cytosol location captured elsewhere. Supporting Evidence: PMID:11772392 an enzyme mainly localized in the cytosol but also found on the cell surface of monocytes
GO:0005764 lysosome	IEA GO_REF:0000044	KEEP AS NON CORE	Summary: Electronic (UniProt SubCell keyword) localization to the lysosome. Corroborated by direct experimental demonstration of ADA activity in purified human fibroblast lysosomes. Reason: Genuine minor localization (~10% of cellular activity is lysosomal), but a secondary compartment relative to the dominant cytosolic pool. Supporting Evidence: PMID:8452534 Human fibroblast lysosomes, purified on Percoll density gradients, contain an
GO:0005886 plasma membrane	IEA GO_REF:0000044	KEEP AS NON CORE	Summary: Electronic (UniProt SubCell keyword) localization to the plasma membrane. Consistent with the ecto-ADA pool, which is a peripheral membrane protein on the extracellular side, tethered by CD26/DPP4. Reason: Correct for the cell-surface (ecto-ADA) pool; a secondary localization relative to the dominant cytosolic activity. The more specific 'external side of plasma membrane' annotation captures the topology better. Supporting Evidence: PMID:16670267 ADA localizes to the endothelial surface and limits the accumulation of extracellular adenosine during hypoxia
GO:0006154 adenosine catabolic process	IEA GO_REF:0000117	ACCEPT	Summary: ARBA machine-learning electronic annotation of the core biological process, adenosine catabolism. Duplicate of the experimentally/phylogenetically supported core BP. Reason: Correct core biological process, consistent with the enzyme's catalytic function. Supporting Evidence: file:human/ADA/ADA-uniprot.txt Plays an important role in purine
GO:0009168 purine ribonucleoside monophosphate biosynthetic process	IEA GO_REF:0000002	REMOVE	Summary: InterPro2GO electronic mapping to purine ribonucleoside monophosphate biosynthesis. ADA is a catabolic deaminase acting on nucleosides (adenosine, 2'-deoxyadenosine); it does not synthesize any purine ribonucleoside monophosphate. Reason: Over-propagated electronic annotation. ADA's product is inosine (a nucleoside, not a monophosphate), and the enzyme is degradative rather than biosynthetic. The InterPro domain family (IPR006650/IPR028893) is shared with AMP deaminases, but human ADA does not perform monophosphate biosynthesis; this term contradicts the enzyme's catabolic biology and should be removed.
GO:0019239 deaminase activity	IEA GO_REF:0000002	MODIFY	Summary: InterPro2GO electronic mapping to the general parent term deaminase activity. Correct but less specific than adenosine deaminase activity (GO:0004000). Reason: The essence is correct but the term is too general. ADA's specific activity is adenosine deaminase activity; the parent 'deaminase activity' should be refined to the specific child. Proposed replacements: adenosine deaminase activity Supporting Evidence: file:human/ADA/ADA-uniprot.txt Catalyzes the hydrolytic deamination of adenosine and 2-
GO:0060205 cytoplasmic vesicle lumen	IEA GO_REF:0000044	REMOVE	Summary: Electronic (UniProt SubCell keyword) localization to cytoplasmic vesicle lumen, transferred by similarity from the rat ortholog (P03958). There is no direct evidence for human ADA in a cytoplasmic vesicle lumen. Reason: Weakly supported electronic annotation transferred by similarity. Human ADA is dominantly cytosolic, with well-documented lysosomal and cell-surface pools; the cytoplasmic vesicle lumen assignment is not experimentally supported for the human protein and is a keyword-driven over-propagation.
GO:0070161 anchoring junction	IEA GO_REF:0000044	MARK AS OVER ANNOTATED	Summary: Electronic (UniProt SubCell keyword 'Cell junction') mapping to anchoring junction. ADA colocalizes with CD26 at the cell surface and its ADA-CD26 axis influences cell adhesion, but there is no evidence it is a structural component of an anchoring junction. Reason: The 'Cell junction' keyword derives from the ecto-ADA/CD26 role in cell-cell adhesion, but mapping this to the specific structural term 'anchoring junction' over-interprets a peripheral, adhesion-modulating function as junctional residency. Retained as a flag rather than removed since the underlying cell-junction association is real.
GO:0005515 protein binding	IPI PMID:28514442 Architecture of the human interactome defines protein commun...	MARK AS OVER ANNOTATED	Summary: High-throughput affinity-purification/mass-spectrometry interactome IPI (interacting partner POTEF/A5A3E0). Bare 'protein binding' conveys no specific molecular function. Reason: Uninformative 'protein binding' term derived from a proteome-scale interactome screen; the POTEF interaction is not a characterized functional partnership for ADA. Per curation guidelines, bare protein binding is not retained as informative MF, but the IPI is not removed.
GO:0005515 protein binding	IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling...	MARK AS OVER ANNOTATED	Summary: High-throughput interactome IPI (BioPlex; interacting partner POTEF/A5A3E0). Bare 'protein binding' conveys no specific molecular function. Reason: Uninformative 'protein binding' from a proteome-scale interactome dataset, capturing the same POTEF association. Not retained as informative MF; not removed.
GO:0005829 cytosol	IEA GO_REF:0000107	ACCEPT	Summary: Ensembl-Compara electronic transfer (from mouse ortholog P03958) that ADA is active in the cytosol. Duplicate of the core cytosolic localization. Reason: Correct primary localization, consistent with the IBA and Reactome/TAS cytosol annotations. Supporting Evidence: PMID:11772392 an enzyme mainly localized in the cytosol but also found on the cell surface of monocytes
GO:0006196 AMP catabolic process	IEA GO_REF:0000107	MARK AS OVER ANNOTATED	Summary: Ensembl-Compara electronic transfer of AMP catabolic process. ADA acts on the nucleosides adenosine and 2'-deoxyadenosine, not directly on the nucleotide AMP; the direct catalytic step on AMP is carried out by other enzymes (AMP deaminase, 5'-nucleotidase). Reason: This is a broad pathway-participation (involved_in) annotation rather than a direct-substrate claim. ADA does participate in overall AMP catabolism downstream (AMP is dephosphorylated to adenosine, which ADA then deaminates to inosine), so the term is not strictly wrong at the pathway level; but it is a nonspecific, ortholog-transferred over-annotation that does not capture ADA's actual catalytic step, so it is marked as over-annotated rather than treated as a core function.
GO:0008270 zinc ion binding	IEA GO_REF:0000107	ACCEPT	Summary: Ensembl-Compara electronic transfer of zinc ion binding. ADA is a zinc metalloenzyme that binds one catalytic Zn2+ per subunit, coordinated by conserved histidine/aspartate residues; this is required for catalysis. Reason: Correct and core molecular-function cofactor binding, directly supported by the crystal structure and by an ADASCID mutation (H15D) that disrupts zinc coordination and abolishes activity. Supporting Evidence: file:human/ADA/ADA-uniprot.txt Binds 1 zinc ion per subunit PMID:7599635 the first naturally occurring mutation of a residue that coordinates
GO:0032263 GMP salvage	IEA GO_REF:0000107	REMOVE	Summary: Ensembl-Compara electronic transfer of GMP salvage. ADA has no role in guanine-nucleotide salvage; it deaminates adenosine/2'-deoxyadenosine and does not act on any guanine-containing metabolite. Reason: Biologically incorrect for ADA's substrate specificity. GMP salvage involves HGPRT/guanine metabolism, entirely separate from adenosine deamination. This is an over-propagated pathway-network annotation and should be removed.
GO:0044209 AMP salvage	IEA GO_REF:0000107	REMOVE	Summary: Ensembl-Compara electronic transfer of AMP salvage. ADA does not catalyze any AMP-salvage step; by deaminating adenosine it in fact diverts the substrate away from adenine/AMP salvage toward the inosine/hypoxanthine catabolic branch. Reason: Over-propagated pathway-network annotation that is at odds with ADA's biology. AMP salvage is carried out by adenine phosphoribosyltransferase and adenosine kinase; ADA is catabolic. Should be removed.
GO:0046059 dAMP catabolic process	IEA GO_REF:0000107	MARK AS OVER ANNOTATED	Summary: Ensembl-Compara electronic transfer of dAMP catabolic process. ADA deaminates the deoxynucleoside 2'-deoxyadenosine, not directly the deoxynucleotide dAMP; the direct catalytic step on dAMP is carried out by other enzymes (e.g. 5'-nucleotidases, deoxynucleotide deaminases). Reason: As for the AMP catabolic-process annotation, this is a broad involved_in pathway term rather than a direct-substrate claim. ADA participates downstream in dAMP catabolism (dAMP is dephosphorylated to 2'-deoxyadenosine, which ADA deaminates to 2'-deoxyinosine), so the term is not strictly wrong at the pathway level; it is a nonspecific, ortholog-transferred over-annotation and is marked as over-annotated rather than treated as a core function.
GO:0046936 2'-deoxyadenosine deaminase activity	IEA GO_REF:0000120	ACCEPT	Summary: Electronic annotation (RHEA:28190) of 2'-deoxyadenosine deaminase activity. ADA hydrolytically deaminates 2'-deoxyadenosine to 2'-deoxyinosine; this activity is the physiologically critical one whose loss drives dATP accumulation in ADA-SCID. Reason: Correct core molecular function alongside adenosine deaminase activity, supported by the second RHEA reaction and by experimental catalytic data. Supporting Evidence: file:human/ADA/ADA-uniprot.txt Catalyzes the hydrolytic deamination of adenosine and 2-
GO:0006805 xenobiotic metabolic process	TAS Reactome:R-HSA-9748784	KEEP AS NON CORE	Summary: Reactome (Drug ADME) annotation reflecting ADA's deamination of nucleoside analog drugs, notably ribavirin (RBV -> RBV-COOH) and cordycepin. This is a pharmacologically important but incidental substrate promiscuity. Reason: A genuine xenobiotic/drug-metabolism role arising from ADA's broad specificity for adenosine-like nucleosides, but secondary to its endogenous purine-catabolic function. Supporting Evidence: file:human/ADA/ADA-uniprot.txt responsible for the deamination of cordycepin
GO:0043101 purine-containing compound salvage	TAS Reactome:R-HSA-74217	ACCEPT	Summary: Reactome (Purine salvage pathway) TAS annotation. ADA participates in the purine salvage/interconversion network by converting adenosine and 2'-deoxyadenosine to their inosine counterparts, which are then further metabolized. Reason: ADA is a bona fide participant in the purine salvage/interconversion pathway; this broader process term is accurate and reflects the enzyme's contribution to purine-containing compound turnover. Supporting Evidence: PMID:9361033 the purine salvage enzyme adenosine deaminase
GO:0005886 plasma membrane	IDA GO_REF:0000052	KEEP AS NON CORE	Summary: Human Protein Atlas immunofluorescence localization to the plasma membrane, consistent with the ecto-ADA cell-surface pool tethered by CD26/DPP4. Reason: Correct for the cell-surface (ecto-ADA) pool; a secondary localization relative to the dominant cytosolic activity. Supporting Evidence: PMID:11999881 indicating surface expression of ADA
GO:0004000 adenosine deaminase activity	IMP PMID:26166670 The Role of G22 A Adenosine Deaminase 1 Gene Polymorphism an...	ACCEPT	Summary: IMP annotation of adenosine deaminase activity from a study of the ADA1 G22A (Asp8Asn/ADA2) polymorphism in fertile vs infertile men, in which ADA isoenzyme activities were measured; the low-activity GA genotype had reduced ADA1 activity. Reason:* Supports the core adenosine deaminase activity of the human enzyme via genotype-linked measurement of ADA1 activity. Supporting Evidence: PMID:26166670 the ADA1 activity with GG genotype was higher than GA carriers in all population
GO:0046936 2'-deoxyadenosine deaminase activity	IMP PMID:9361033 An adenosine deaminase (ADA) allele contains two newly ident...	ACCEPT	Summary: IMP annotation from characterization of ADASCID mutant alleles (Y97C, L106V) whose loss of ADA activity is measured, establishing the enzyme's deoxyadenosine-deaminase function via mutation-driven activity loss and toxic dATP/deoxyadenosine accumulation. Reason: Loss-of-function mutations abolishing enzyme activity, coupled with accumulation of the deoxyadenosine substrate, directly support ADA's 2'-deoxyadenosine deaminase activity as a core function. Supporting Evidence: PMID:9361033 directly with the accumulation of the toxic metabolites deoxyATP and deoxyadenosine
GO:0019239 deaminase activity	EXP PMID:2166947 Hot spot mutations in adenosine deaminase deficiency.	MODIFY	Summary: Experimental annotation to the general parent 'deaminase activity' from characterization of hot-spot ADASCID mutations (e.g. Arg76Trp) that alter mutant ADA enzyme activity. The specific activity is adenosine deaminase activity. Reason: Correct in essence but too general; the mutations characterized affect adenosine deaminase activity specifically and the term should be refined to GO:0004000. Proposed replacements: adenosine deaminase activity Supporting Evidence: PMID:2166947 resulting in Arg76 to Trp
GO:0019239 deaminase activity	EXP PMID:2783588 Identification of a point mutation resulting in a heat-labil...	MODIFY	Summary: Experimental annotation to the general parent 'deaminase activity' from identification of the Pro297Gln mutation causing a heat-labile ADA in partial ADA deficiency. The specific activity is adenosine deaminase activity. Reason: Correct in essence but too general; refine to the specific adenosine deaminase activity term. Proposed replacements: adenosine deaminase activity Supporting Evidence: PMID:2783588 replacement of a proline
GO:0019239 deaminase activity	EXP PMID:3182793 Mutant human adenosine deaminase alleles and their expressio...	MODIFY	Summary: Experimental annotation to the general parent 'deaminase activity'. Mutant ADA alleles (e.g. Arg101Trp, Arg211His, Ala329Val) expressed by transfection failed to produce functional enzyme, demonstrating loss of adenosine deaminase activity. Reason: Correct in essence but too general; refine to the specific adenosine deaminase activity term. Proposed replacements: adenosine deaminase activity Supporting Evidence: PMID:3182793 they do not encode a
GO:0019239 deaminase activity	TAS Reactome:R-HSA-9754964	MODIFY	Summary: Reactome TAS annotation (ADA deamidates ribavirin) to the general parent 'deaminase activity'. The specific activity is adenosine deaminase activity acting on ribavirin, an adenosine analog. Reason: Correct in essence but too general; the underlying reaction is ADA's adenosine deaminase activity applied to a nucleoside-analog drug. Refine to GO:0004000. Proposed replacements: adenosine deaminase activity Supporting Evidence: file:human/ADA/ADA-uniprot.txt Catalyzes the hydrolytic deamination of adenosine and 2-
GO:0014074 response to purine-containing compound	IDA PMID:25644539 Adenosine derived from ecto-nucleotidases in calcific aortic...	KEEP AS NON CORE	Summary: IDA annotation (MGI) from a study of calcific aortic valve disease in which adenosine, generated by ecto-nucleotidases, drives valve-interstitial-cell mineralization through the A2a adenosine receptor; ADA is part of the extracellular adenosine-metabolizing machinery in this context. Reason: A context-specific (disease-associated) response annotation downstream of ADA's role in extracellular adenosine handling; peripheral to the core catabolic function. Supporting Evidence: PMID:25644539 adenosine stimulated the mineralization of
GO:0046085 adenosine metabolic process	IDA PMID:25644539 Adenosine derived from ecto-nucleotidases in calcific aortic...	KEEP AS NON CORE	Summary: IDA annotation (MGI) placing ADA in adenosine metabolism in the context of calcific aortic valve disease. Adenosine metabolic process is a valid broader parent of ADA's core adenosine catabolic activity. Reason: Correct but broader than the more specific 'adenosine catabolic process' that captures ADA's defining role. Retained as accurate; the specific catabolic term is preferred for the core function. Supporting Evidence: PMID:25644539 adenosine stimulated the mineralization of
GO:0005829 cytosol	TAS Reactome:R-HSA-9734745	ACCEPT	Summary: Reactome TAS cytosolic localization (defective ADA does not deaminate (deoxy)adenosine). Consistent with the core cytosolic site of ADA activity. Reason: Correct primary localization, redundant with the IBA/IEA/other Reactome cytosol annotations. Supporting Evidence: PMID:11772392 an enzyme mainly localized in the cytosol but also found on the cell surface of monocytes
GO:0005829 cytosol	TAS Reactome:R-HSA-74241	ACCEPT	Summary: Reactome TAS cytosolic localization (ADA catalyzes the deamination of (deoxy)adenosine). Consistent with the core cytosolic site of ADA activity. Reason: Correct primary localization, redundant with the other cytosol annotations. Supporting Evidence: PMID:11772392 an enzyme mainly localized in the cytosol but also found on the cell surface of monocytes
GO:0005829 cytosol	TAS Reactome:R-HSA-9754964	ACCEPT	Summary: Reactome TAS cytosolic localization (ADA deamidates ribavirin). Consistent with the core cytosolic site of ADA activity. Reason: Correct primary localization, redundant with the other cytosol annotations. Supporting Evidence: PMID:11772392 an enzyme mainly localized in the cytosol but also found on the cell surface of monocytes
GO:0004000 adenosine deaminase activity	IDA PMID:8894685 Full genetic rescue of adenosine deaminase-deficient mice th...	ACCEPT	Summary: IDA annotation from full genetic rescue of ADA-deficient mice by the human ADA gene, demonstrating that the human enzyme provides functional adenosine deaminase activity that complements murine ADA in all tissues. Reason: In vivo functional complementation is strong support that the human protein carries out adenosine deaminase activity; the lethal ADA-deficient phenotype is due to absence of the enzyme. Supporting Evidence: PMID:8894685 human ADA can complement murine ADA in
GO:0006154 adenosine catabolic process	IDA PMID:8894685 Full genetic rescue of adenosine deaminase-deficient mice th...	ACCEPT	Summary: IDA annotation that ADA acts upstream of or within adenosine catabolism, from mouse genetic rescue showing the lethal ADA-deficient phenotype is corrected by restoring ADA function. Reason: The rescue of ADA-deficient mice by the human gene confirms ADA's role in adenosine catabolism in vivo; this is the core biological process. Supporting Evidence: PMID:8894685 lethal phenotype of ADA-deficient mice is due to the absence
GO:0046103 inosine biosynthetic process	IDA PMID:8894685 Full genetic rescue of adenosine deaminase-deficient mice th...	ACCEPT	Summary: IDA annotation that ADA acts upstream of or within inosine biosynthesis; inosine is the direct product of adenosine deamination, restored upon complementation of ADA-deficient mice by the human gene. Reason: ADA directly generates inosine; valid process annotation downstream of the core catalytic reaction, supported by in vivo complementation. Supporting Evidence: PMID:8894685 restoration of viability through introduction of the
GO:0004000 adenosine deaminase activity	ISS GO_REF:0000024	ACCEPT	Summary: Sequence-similarity (ISS from mouse P03958) transfer of the core adenosine deaminase activity. Redundant with the directly demonstrated human activity. Reason: Correct core molecular function, well supported by experimental data for the human enzyme. Supporting Evidence: file:human/ADA/ADA-uniprot.txt Catalyzes the hydrolytic deamination of adenosine and 2-
GO:0006154 adenosine catabolic process	ISS GO_REF:0000024	ACCEPT	Summary: Sequence-similarity (ISS) transfer of the core adenosine catabolic process. Redundant with experimentally supported annotations. Reason: Correct core biological process. Supporting Evidence: file:human/ADA/ADA-uniprot.txt Plays an important role in purine
GO:0008270 zinc ion binding	ISS GO_REF:0000024	ACCEPT	Summary: Sequence-similarity (ISS) transfer of zinc ion binding. ADA binds one catalytic zinc per subunit; conserved across the family and required for catalysis. Reason: Correct core cofactor-binding function, supported by structure and by disease mutations affecting zinc-coordinating residues. Supporting Evidence: file:human/ADA/ADA-uniprot.txt Binds 1 zinc ion per subunit
GO:0046103 inosine biosynthetic process	ISS GO_REF:0000024	ACCEPT	Summary: Sequence-similarity (ISS) transfer of inosine biosynthetic process; inosine is the direct product of ADA-catalyzed adenosine deamination. Reason: Valid process downstream of the core catalytic reaction. Supporting Evidence: PMID:8452534 the conversion of [3H]adenosine into [3H]inosine was proportional to incubation time
GO:0005515 protein binding	IPI PMID:8101391 Direct association of adenosine deaminase with a T cell acti...	MARK AS OVER ANNOTATED	Summary: IPI documenting the direct, specific association of ADA with CD26/DPP4 (P27487) on the T-cell surface, through the extracellular domain of CD26. This is the physiologically important ecto-ADA anchoring interaction. Reason: The interaction itself is real and biologically important, but the term 'protein binding' is uninformative. The functional consequences of the ADA-CD26 interaction are already captured by the T-cell activation and cell-adhesion process annotations; the bare MF term is not retained as informative, though the IPI is not removed. Supporting Evidence: PMID:8101391 an in vitro binding assay showed that the binding was through the extracellular domain of CD26
GO:0004000 adenosine deaminase activity	IDA PMID:11999881 Anti-adenosine deaminase antibodies in lupus erythematosus.	ACCEPT	Summary: IDA annotation from a study of anti-ADA autoantibodies in lupus, which used purified/commercial ADA and detected ADA (the ADA1 40 kDa component) on cells; supports the identity and activity of the human ADA protein. Reason: Consistent with the well-established core adenosine deaminase activity of human ADA1. Supporting Evidence: PMID:11999881 corresponding to ADA1, the major component file:human/ADA/ADA-uniprot.txt Catalyzes the hydrolytic deamination of adenosine and 2-
GO:0016020 membrane	IDA PMID:11999881 Anti-adenosine deaminase antibodies in lupus erythematosus.	MODIFY	Summary: IDA annotation to the very general term 'membrane', from immunofluorescence showing anti-ADA antibodies stain the cell surface of HEp-2 cells and lymphocytes. The staining reflects the ecto-ADA (cell-surface) pool. Reason: The generic 'membrane' term under-specifies the observation; the data show cell-surface/plasma-membrane localization of ecto-ADA. Refine to cell surface. Proposed replacements: cell surface Supporting Evidence: PMID:11999881 surface of HEp-2 cells and lymphocytes, indicating surface expression of ADA
GO:0001666 response to hypoxia	IDA PMID:16670267 Endothelial catabolism of extracellular adenosine during hyp...	KEEP AS NON CORE	Summary: IDA annotation that ADA participates in the hypoxia response; endothelial ADA (and its partner CD26) are induced by hypoxia at mRNA and protein levels, localizing ADA activity to the cell surface to clear elevated extracellular adenosine. Reason: A genuine, experimentally demonstrated regulatory response (hypoxia-induced ADA/CD26), but a physiological/context-specific role secondary to the core catabolic function. Supporting Evidence: PMID:16670267 hypoxia induces endothelial ADA and CD26
GO:0004000 adenosine deaminase activity	IDA PMID:16670267 Endothelial catabolism of extracellular adenosine during hyp...	ACCEPT	Summary: IDA annotation of adenosine deaminase activity; the study confirmed induction of enzymatically active ADA in hypoxic endothelium, degrading extracellular adenosine to inosine. Reason: Directly demonstrated core adenosine deaminase activity of the human enzyme. Supporting Evidence: PMID:16670267 increasing the endothelial capacity to metabolize adenosine to inosine
GO:0004000 adenosine deaminase activity	IDA PMID:8452534 Demonstration of adenosine deaminase activity in human fibro...	ACCEPT	Summary: IDA annotation of adenosine deaminase activity, from direct assay of ADA activity (adenosine to inosine, Km 37 uM) in purified human fibroblast lysosomes. Reason: Direct biochemical demonstration of the core adenosine deaminase activity of the human enzyme. Supporting Evidence: PMID:8452534 the conversion of [3H]adenosine into [3H]inosine was proportional to incubation time
GO:0004000 adenosine deaminase activity	IDA PMID:9361033 An adenosine deaminase (ADA) allele contains two newly ident...	ACCEPT	Summary: IDA annotation of adenosine deaminase activity from expression of wild-type and mutant ADA cDNAs; the Y97C mutant retained only detectable but markedly reduced activity, and wild-type ADA showed normal activity. Reason: Directly measured expressed ADA activity supports the core adenosine deaminase function. Supporting Evidence: PMID:9361033 detectable but markedly reduced activity
GO:0005515 protein binding	IPI PMID:14684150 3D structure of the CD26-ADA complex obtained by cryo-EM and...	MARK AS OVER ANNOTATED	Summary: IPI from a cryo-EM 3D structure of the CD26-ADA complex (partner P27487/DPP4), mapping the ADA-binding site across CD26 beta-propeller blades 4 and 5. Documents the specific ADA-CD26 interaction. Reason: Real, structurally characterized ADA-CD26 interaction, but 'protein binding' is uninformative as a molecular function; the interaction's biological role is captured by the ecto-ADA process annotations. IPI retained, not removed. Supporting Evidence: PMID:14684150 ADA binding occurs at the outer edges of the
GO:0005515 protein binding	IPI PMID:7594462 Expression of ecto-adenosine deaminase and CD26 in human T c...	MARK AS OVER ANNOTATED	Summary: IPI documenting the ADA-CD26 (P27487) interaction on the T-cell surface, where ADA and CD26 colocalize and exogenous ADA produces an enzyme-independent costimulatory synergism in T-cell activation. Reason: Genuine, functionally important ADA-CD26 interaction, but 'protein binding' is uninformative; the costimulatory role is captured by the T-cell activation process annotation. IPI retained, not removed. Supporting Evidence: PMID:7594462 addition of ADA produced an enzyme-independent synergism
GO:0005764 lysosome	IDA PMID:8452534 Demonstration of adenosine deaminase activity in human fibro...	KEEP AS NON CORE	Summary: IDA localization to the lysosome, from direct demonstration of ADA activity in Percoll-purified human fibroblast lysosomes (~10% of total cellular ADA activity). Reason: Genuine but minor secondary localization relative to the dominant cytosolic pool. Supporting Evidence: PMID:8452534 adenosine deaminase (ADA) activity that accounts for approximately 10% of the total ADA activity
GO:0006154 adenosine catabolic process	IDA PMID:16670267 Endothelial catabolism of extracellular adenosine during hyp...	ACCEPT	Summary: IDA annotation of adenosine catabolic process; hypoxia-induced endothelial ADA (with CD26) increases the capacity to catabolize extracellular adenosine to inosine. Reason: Direct demonstration of ADA's core biological process (adenosine catabolism) in a physiological setting. Supporting Evidence: PMID:16670267 increasing the endothelial capacity to metabolize adenosine to inosine
GO:0009897 external side of plasma membrane	IDA PMID:16670267 Endothelial catabolism of extracellular adenosine during hyp...	KEEP AS NON CORE	Summary: IDA localization of ecto-ADA to the external side of the plasma membrane, tethered by CD26; surface binding was blocked by HIV gp120, which competes for ADA-CD26 binding. Reason: Genuine cell-surface (extracellular) localization of the ecto-ADA pool; secondary to the dominant cytosolic activity. Supporting Evidence: PMID:16670267 ADA localizes to the endothelial surface and limits the accumulation of extracellular adenosine during hypoxia
GO:0009897 external side of plasma membrane	IDA PMID:7759315 Surface adenosine deaminase. A novel B-cell marker in chroni...	KEEP AS NON CORE	Summary: IDA localization of surface ADA on the plasma membrane of mononuclear blood cells detected by flow cytometry; surface ADA is a proposed B-cell marker in chronic lymphocytic leukemia. Reason: Genuine cell-surface (ecto-ADA) localization; secondary to the dominant cytosolic pool. Supporting Evidence: PMID:7759315 surface ADA might be considered a novel marker for CLL
GO:0009986 cell surface	IDA PMID:11772392 Regulation of epithelial and lymphocyte cell adhesion by ade...	KEEP AS NON CORE	Summary: IDA localization of ADA to the cell surface, where cell-surface ADA (e.g. on Caco-2 epithelial cells) participates in ADA-CD26-mediated lymphocyte-epithelial adhesion. Reason: Genuine ecto-ADA cell-surface localization; secondary to the core cytosolic pool. Supporting Evidence: PMID:11772392 an enzyme mainly localized in the cytosol but also found on the cell surface of monocytes
GO:0009986 cell surface	IDA PMID:7594462 Expression of ecto-adenosine deaminase and CD26 in human T c...	KEEP AS NON CORE	Summary: IDA localization of surface ADA on activated human T cells (flow cytometry), where ADA colocalizes with CD26 on the T-cell surface. Reason: Genuine ecto-ADA cell-surface localization on lymphocytes; secondary to the core cytosolic pool. Supporting Evidence: PMID:7594462 colocalized on the surface of T cells
GO:0032261 purine nucleotide salvage	IMP PMID:9361033 An adenosine deaminase (ADA) allele contains two newly ident...	KEEP AS NON CORE	Summary: IMP annotation placing ADA in purine nucleotide salvage; loss-of-function ADA mutations disrupt purine interconversion and cause toxic (deoxy)adenosine/dATP accumulation. ADA is described as a purine salvage enzyme. Reason: ADA participates in the broader purine salvage/interconversion network, but its own committed reaction is adenosine catabolism (the core process). Retained as an accurate pathway-level annotation. Supporting Evidence: PMID:9361033 the purine salvage enzyme adenosine deaminase
GO:0033632 regulation of cell-cell adhesion mediated by integrin	IDA PMID:11772392 Regulation of epithelial and lymphocyte cell adhesion by ade...	KEEP AS NON CORE	Summary: IDA annotation from experiments showing the ADA-CD26 interaction regulates lymphocyte-epithelial cell adhesion, with exogenous ADA increasing expression of activated integrins on T-cell lines (integrin activation assays). Reason: A genuine extra-enzymatic (moonlighting) role of ecto-ADA via CD26 in modulating integrin-mediated cell adhesion; secondary to the core catabolic function. Supporting Evidence: PMID:11772392 FACS analysis revealed a higher expression of activated
GO:0042110 T cell activation	IDA PMID:7594462 Expression of ecto-adenosine deaminase and CD26 in human T c...	KEEP AS NON CORE	Summary: IDA annotation that ADA acts in T cell activation; exogenous ADA binding to CD26 produces a costimulatory (enzyme-independent) synergism in the TCR-CD3 activation response. Reason: A genuine moonlighting immunological role of ecto-ADA via CD26, distinct from and secondary to the core cytosolic catalytic function. Supporting Evidence: PMID:7594462 binding to CD26 produces a costimulatory response in T cell activation events
GO:0060169 negative regulation of adenosine receptor signaling pathway	IDA PMID:16670267 Endothelial catabolism of extracellular adenosine during hyp...	KEEP AS NON CORE	Summary: IDA annotation that ADA negatively regulates adenosine-receptor signaling by clearing extracellular adenosine (the receptor agonist), limiting adenosine accumulation and downstream signaling in hypoxic endothelium. Reason: A genuine signaling consequence of ecto-ADA's extracellular adenosine clearance, secondary to the core catabolic activity. Context-dependent, since ADA can also positively modulate adenosine-receptor agonist affinity. Supporting Evidence: PMID:16670267 ADA localizes to the endothelial surface and limits the accumulation of extracellular adenosine during hypoxia
GO:0004000 adenosine deaminase activity	IDA PMID:3182793 Mutant human adenosine deaminase alleles and their expressio...	ACCEPT	Summary: IDA annotation of adenosine deaminase activity; wild-type ADA cDNA expressed by transfection produced ADA enzymatic levels ~40-fold higher than mutant sequences, confirming the enzyme's catalytic activity. Reason: Directly measured expressed ADA enzyme activity supports the core adenosine deaminase function; mutant alleles failed to encode functional enzyme. Supporting Evidence: PMID:3182793 they do not encode a
GO:0008270 zinc ion binding	IMP PMID:7599635 Four new adenosine deaminase mutations, altering a zinc-bind...	ACCEPT	Summary: IMP annotation of zinc ion binding from the ADASCID His15Asp mutation, the first naturally occurring mutation of a residue that directly coordinates the enzyme-associated zinc ion; H15D abolishes ADA activity. Reason: A disease mutation of a direct zinc-coordinating residue that abolishes activity provides strong functional evidence for ADA's core zinc-binding cofactor role. Supporting Evidence: PMID:7599635 the first naturally occurring mutation of a residue that coordinates

📄 View Raw YAML

id: P00813
gene_symbol: ADA
product_type: PROTEIN
status: INITIALIZED
taxon:
  id: NCBITaxon:9606
  label: Homo sapiens
description: Adenosine deaminase (ADA1; EC 3.5.4.4) is a zinc-dependent hydrolase of
  purine catabolism that catalyzes the irreversible hydrolytic deamination of adenosine
  to inosine and of 2'-deoxyadenosine to 2'-deoxyinosine, releasing ammonia. Each subunit
  binds one catalytic zinc ion (coordinated by conserved histidine and aspartate residues)
  and adopts the metallo-dependent hydrolase (TIM-barrel) fold of the adenosine/AMP deaminase
  family. By clearing (deoxy)adenosine it maintains adenosine homeostasis and is essential
  in lymphocytes, where loss of activity leads to toxic intracellular accumulation of
  2'-deoxyadenosine and dATP; complete deficiency causes adenosine-deaminase-deficient severe
  combined immunodeficiency (ADA-SCID, a T-B-NK-negative SCID), while a partial excess of
  activity is associated with hereditary hemolytic anemia. The enzyme is predominantly
  cytosolic (also detectable in lysosomes), but a fraction is found at the cell surface as
  ecto-ADA, where it is anchored as a peripheral membrane protein via the ectoenzyme CD26/DPP4;
  ecto-ADA catabolizes extracellular adenosine (notably in hypoxic endothelium), modulates
  adenosine-receptor signaling, and serves as a T-cell costimulatory molecule and regulator
  of lymphocyte-epithelial cell adhesion. ADA also deaminates the nucleoside drug ribavirin
  and the natural product cordycepin.
existing_annotations:
- term:
    id: GO:0004000
    label: adenosine deaminase activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: Phylogenetic (IBA) inference of the defining molecular function of ADA,
      the hydrolytic deamination of adenosine to inosine. This is the core catalytic
      activity of the protein and is supported experimentally in human ADA.
    action: ACCEPT
    reason: Core molecular function of ADA, conserved across the adenosine deaminase
      family and directly demonstrated for the human enzyme by catalytic-activity
      and biophysicochemical studies.
    supported_by:
    - reference_id: file:human/ADA/ADA-uniprot.txt
      supporting_text: Catalyzes the hydrolytic deamination of adenosine and 2-
    - reference_id: PMID:8452534
      supporting_text: the conversion of [3H]adenosine into [3H]inosine was proportional
        to incubation time
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  review:
    summary: Phylogenetic inference that ADA acts in the cytosol. ADA is predominantly
      a cytosolic enzyme, consistent with its role in intracellular purine catabolism.
    action: ACCEPT
    reason: The cytosol is the primary site of ADA activity; UniProt and multiple
      Reactome/TAS annotations place the enzyme in the cytosol, and the cell-surface
      (ecto-ADA) pool is a secondary localization.
    supported_by:
    - reference_id: PMID:11772392
      supporting_text: an enzyme mainly localized in the cytosol but also found on
        the cell surface of monocytes
- term:
    id: GO:0042110
    label: T cell activation
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: Involvement in T cell activation, inferred phylogenetically and supported
      experimentally through the ecto-ADA/CD26 costimulatory axis on the T-cell surface.
    action: KEEP_AS_NON_CORE
    reason: This is a genuine but moonlighting (extra-enzymatic / cell-surface) role
      of ADA, distinct from its core cytosolic catalytic function in purine catabolism.
      Cell-surface ADA bound to CD26 provides a costimulatory signal in T cell activation.
    supported_by:
    - reference_id: PMID:7594462
      supporting_text: binding to CD26 produces a costimulatory response in T cell
        activation events
- term:
    id: GO:0045187
    label: regulation of circadian sleep/wake cycle, sleep
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: Phylogenetic inference linking ADA to regulation of sleep. Adenosine
      is a well-established somnogen, and the common ADA*2 (Asp8Asn) polymorphism,
      which lowers ADA activity, enhances deep sleep and slow-wave activity in humans.
    action: KEEP_AS_NON_CORE
    reason: A genuine physiological consequence of ADA controlling adenosine tone in
      the brain, but downstream of and secondary to the core catabolic activity rather
      than a defining molecular function. Supported by human polymorphism data.
    supported_by:
    - reference_id: file:human/ADA/ADA-uniprot.txt
      supporting_text: It specifically enhances deep sleep and slow-wave activity
- term:
    id: GO:0006154
    label: adenosine catabolic process
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: Phylogenetic inference that ADA participates in adenosine catabolism.
      This is the core biological process for ADA, the committed step converting adenosine
      to inosine in the purine degradation pathway.
    action: ACCEPT
    reason: Adenosine catabolism is the defining biological role of ADA and is directly
      supported by its catalytic activity and by the phenotype of ADA-deficient cells,
      which accumulate the substrate (deoxy)adenosine.
    supported_by:
    - reference_id: file:human/ADA/ADA-uniprot.txt
      supporting_text: Plays an important role in purine
    - reference_id: PMID:9361033
      supporting_text: the purine salvage enzyme adenosine deaminase
- term:
    id: GO:0009897
    label: external side of plasma membrane
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  review:
    summary: Phylogenetic inference that a pool of ADA is active on the external side
      of the plasma membrane (ecto-ADA), anchored via CD26/DPP4. This is corroborated
      by direct experimental localization in human cells.
    action: KEEP_AS_NON_CORE
    reason: Ecto-ADA is a genuine second localization of the enzyme, but represents
      a moonlighting/cell-surface pool secondary to the predominant cytosolic activity.
    supported_by:
    - reference_id: PMID:16670267
      supporting_text: ADA localizes to the endothelial surface and limits the accumulation
        of extracellular adenosine during hypoxia
- term:
    id: GO:0060169
    label: negative regulation of adenosine receptor signaling pathway
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: Inference that ADA negatively regulates adenosine-receptor signaling.
      By catabolizing extracellular adenosine (the receptor agonist), ecto-ADA reduces
      adenosine-receptor activation; the net effect can be complex, since ADA can also
      allosterically enhance receptor agonist affinity.
    action: KEEP_AS_NON_CORE
    reason: A real downstream signaling consequence of ADA's extracellular adenosine
      clearance, but secondary to the core catabolic activity rather than a defining
      molecular function. Note the effect is context-dependent (ADA also acts as a
      positive allosteric modulator of ADORA1/ADORA2A).
    supported_by:
    - reference_id: PMID:16670267
      supporting_text: increasing the endothelial capacity to metabolize adenosine
        to inosine
- term:
    id: GO:0043103
    label: hypoxanthine salvage
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: Phylogenetic inference associating ADA with hypoxanthine salvage. ADA
      produces inosine; hypoxanthine is generated downstream by purine nucleoside
      phosphorylase (PNP), not by ADA itself.
    action: MARK_AS_OVER_ANNOTATED
    reason: ADA contributes to purine salvage upstream by generating inosine, but it
      does not catalyze any step producing or reutilizing hypoxanthine. Annotating
      ADA to hypoxanthine salvage over-extends the enzyme into a downstream pathway
      step carried out by other enzymes (PNP, HPRT). The upstream inosine-biosynthesis
      and adenosine-catabolism annotations already capture ADA's true contribution.
    propagation_review:
      root_cause: TERM_SCOPING_PROBLEM
      failure_modes:
      - GRANULARITY_MISMATCH
      source_entities:
      - source_id: UniProtKB:P22333
        source_label: ADA family ortholog
        comment: Family-level purine-salvage framing; ADA generates inosine but does
          not perform hypoxanthine salvage, which is downstream (PNP/HPRT).
- term:
    id: GO:0046103
    label: inosine biosynthetic process
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: Phylogenetic inference that ADA contributes to inosine biosynthesis. Inosine
      is the direct reaction product of adenosine deamination by ADA.
    action: ACCEPT
    reason: ADA directly produces inosine from adenosine, so it is genuinely involved
      in inosine biosynthesis. This is a valid process-level annotation directly downstream
      of the core catalytic reaction.
    supported_by:
    - reference_id: PMID:8452534
      supporting_text: the conversion of [3H]adenosine into [3H]inosine was proportional
        to incubation time
- term:
    id: GO:0004000
    label: adenosine deaminase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: enables
  review:
    summary: Electronic annotation (multiple IEA methods, incl. RHEA:24408 mapping)
      of the core adenosine deaminase activity. Duplicate of the experimentally and
      phylogenetically supported core MF.
    action: ACCEPT
    reason: Correct core molecular function, consistent with the RHEA reaction and
      experimental catalytic-activity data.
    supported_by:
    - reference_id: file:human/ADA/ADA-uniprot.txt
      supporting_text: Catalyzes the hydrolytic deamination of adenosine and 2-
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: located_in
  review:
    summary: Electronic localization to the cytoplasm. Consistent with ADA being a
      predominantly cytosolic enzyme, though cytosol (GO:0005829) is the more specific
      and better-supported term.
    action: KEEP_AS_NON_CORE
    reason: Correct but less specific than the cytosol annotation. Retained as accurate
      but non-core relative to the cytosol location captured elsewhere.
    supported_by:
    - reference_id: PMID:11772392
      supporting_text: an enzyme mainly localized in the cytosol but also found on
        the cell surface of monocytes
- term:
    id: GO:0005764
    label: lysosome
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: Electronic (UniProt SubCell keyword) localization to the lysosome. Corroborated
      by direct experimental demonstration of ADA activity in purified human fibroblast
      lysosomes.
    action: KEEP_AS_NON_CORE
    reason: Genuine minor localization (~10% of cellular activity is lysosomal), but
      a secondary compartment relative to the dominant cytosolic pool.
    supported_by:
    - reference_id: PMID:8452534
      supporting_text: Human fibroblast lysosomes, purified on Percoll density gradients,
        contain an
- term:
    id: GO:0005886
    label: plasma membrane
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: Electronic (UniProt SubCell keyword) localization to the plasma membrane.
      Consistent with the ecto-ADA pool, which is a peripheral membrane protein on
      the extracellular side, tethered by CD26/DPP4.
    action: KEEP_AS_NON_CORE
    reason: Correct for the cell-surface (ecto-ADA) pool; a secondary localization
      relative to the dominant cytosolic activity. The more specific 'external side
      of plasma membrane' annotation captures the topology better.
    supported_by:
    - reference_id: PMID:16670267
      supporting_text: ADA localizes to the endothelial surface and limits the accumulation
        of extracellular adenosine during hypoxia
- term:
    id: GO:0006154
    label: adenosine catabolic process
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  qualifier: involved_in
  review:
    summary: ARBA machine-learning electronic annotation of the core biological process,
      adenosine catabolism. Duplicate of the experimentally/phylogenetically supported
      core BP.
    action: ACCEPT
    reason: Correct core biological process, consistent with the enzyme's catalytic
      function.
    supported_by:
    - reference_id: file:human/ADA/ADA-uniprot.txt
      supporting_text: Plays an important role in purine
- term:
    id: GO:0009168
    label: purine ribonucleoside monophosphate biosynthetic process
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: involved_in
  review:
    summary: InterPro2GO electronic mapping to purine ribonucleoside monophosphate
      biosynthesis. ADA is a catabolic deaminase acting on nucleosides (adenosine,
      2'-deoxyadenosine); it does not synthesize any purine ribonucleoside monophosphate.
    action: REMOVE
    reason: Over-propagated electronic annotation. ADA's product is inosine (a nucleoside,
      not a monophosphate), and the enzyme is degradative rather than biosynthetic.
      The InterPro domain family (IPR006650/IPR028893) is shared with AMP deaminases,
      but human ADA does not perform monophosphate biosynthesis; this term contradicts
      the enzyme's catabolic biology and should be removed.
- term:
    id: GO:0019239
    label: deaminase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: enables
  review:
    summary: InterPro2GO electronic mapping to the general parent term deaminase activity.
      Correct but less specific than adenosine deaminase activity (GO:0004000).
    action: MODIFY
    reason: The essence is correct but the term is too general. ADA's specific activity
      is adenosine deaminase activity; the parent 'deaminase activity' should be refined
      to the specific child.
    proposed_replacement_terms:
    - id: GO:0004000
      label: adenosine deaminase activity
    supported_by:
    - reference_id: file:human/ADA/ADA-uniprot.txt
      supporting_text: Catalyzes the hydrolytic deamination of adenosine and 2-
- term:
    id: GO:0060205
    label: cytoplasmic vesicle lumen
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: Electronic (UniProt SubCell keyword) localization to cytoplasmic vesicle
      lumen, transferred by similarity from the rat ortholog (P03958). There is no
      direct evidence for human ADA in a cytoplasmic vesicle lumen.
    action: REMOVE
    reason: Weakly supported electronic annotation transferred by similarity. Human
      ADA is dominantly cytosolic, with well-documented lysosomal and cell-surface
      pools; the cytoplasmic vesicle lumen assignment is not experimentally supported
      for the human protein and is a keyword-driven over-propagation.
- term:
    id: GO:0070161
    label: anchoring junction
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: Electronic (UniProt SubCell keyword 'Cell junction') mapping to anchoring
      junction. ADA colocalizes with CD26 at the cell surface and its ADA-CD26 axis
      influences cell adhesion, but there is no evidence it is a structural component
      of an anchoring junction.
    action: MARK_AS_OVER_ANNOTATED
    reason: The 'Cell junction' keyword derives from the ecto-ADA/CD26 role in cell-cell
      adhesion, but mapping this to the specific structural term 'anchoring junction'
      over-interprets a peripheral, adhesion-modulating function as junctional residency.
      Retained as a flag rather than removed since the underlying cell-junction association
      is real.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:28514442
  qualifier: enables
  review:
    summary: High-throughput affinity-purification/mass-spectrometry interactome IPI
      (interacting partner POTEF/A5A3E0). Bare 'protein binding' conveys no specific
      molecular function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Uninformative 'protein binding' term derived from a proteome-scale interactome
      screen; the POTEF interaction is not a characterized functional partnership for
      ADA. Per curation guidelines, bare protein binding is not retained as informative
      MF, but the IPI is not removed.
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:33961781
  qualifier: enables
  review:
    summary: High-throughput interactome IPI (BioPlex; interacting partner POTEF/A5A3E0).
      Bare 'protein binding' conveys no specific molecular function.
    action: MARK_AS_OVER_ANNOTATED
    reason: Uninformative 'protein binding' from a proteome-scale interactome dataset,
      capturing the same POTEF association. Not retained as informative MF; not removed.
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: is_active_in
  review:
    summary: Ensembl-Compara electronic transfer (from mouse ortholog P03958) that
      ADA is active in the cytosol. Duplicate of the core cytosolic localization.
    action: ACCEPT
    reason: Correct primary localization, consistent with the IBA and Reactome/TAS
      cytosol annotations.
    supported_by:
    - reference_id: PMID:11772392
      supporting_text: an enzyme mainly localized in the cytosol but also found on
        the cell surface of monocytes
- term:
    id: GO:0006196
    label: AMP catabolic process
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: involved_in
  review:
    summary: Ensembl-Compara electronic transfer of AMP catabolic process. ADA acts
      on the nucleosides adenosine and 2'-deoxyadenosine, not directly on the nucleotide
      AMP; the direct catalytic step on AMP is carried out by other enzymes (AMP deaminase,
      5'-nucleotidase).
    action: MARK_AS_OVER_ANNOTATED
    reason: This is a broad pathway-participation (involved_in) annotation rather than
      a direct-substrate claim. ADA does participate in overall AMP catabolism downstream
      (AMP is dephosphorylated to adenosine, which ADA then deaminates to inosine), so
      the term is not strictly wrong at the pathway level; but it is a nonspecific,
      ortholog-transferred over-annotation that does not capture ADA's actual catalytic
      step, so it is marked as over-annotated rather than treated as a core function.
- term:
    id: GO:0008270
    label: zinc ion binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: enables
  review:
    summary: Ensembl-Compara electronic transfer of zinc ion binding. ADA is a zinc
      metalloenzyme that binds one catalytic Zn2+ per subunit, coordinated by conserved
      histidine/aspartate residues; this is required for catalysis.
    action: ACCEPT
    reason: Correct and core molecular-function cofactor binding, directly supported
      by the crystal structure and by an ADASCID mutation (H15D) that disrupts zinc
      coordination and abolishes activity.
    supported_by:
    - reference_id: file:human/ADA/ADA-uniprot.txt
      supporting_text: Binds 1 zinc ion per subunit
    - reference_id: PMID:7599635
      supporting_text: the first naturally occurring mutation of a residue that coordinates
- term:
    id: GO:0032263
    label: GMP salvage
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: involved_in
  review:
    summary: Ensembl-Compara electronic transfer of GMP salvage. ADA has no role in
      guanine-nucleotide salvage; it deaminates adenosine/2'-deoxyadenosine and does
      not act on any guanine-containing metabolite.
    action: REMOVE
    reason: Biologically incorrect for ADA's substrate specificity. GMP salvage involves
      HGPRT/guanine metabolism, entirely separate from adenosine deamination. This
      is an over-propagated pathway-network annotation and should be removed.
- term:
    id: GO:0044209
    label: AMP salvage
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: involved_in
  review:
    summary: Ensembl-Compara electronic transfer of AMP salvage. ADA does not catalyze
      any AMP-salvage step; by deaminating adenosine it in fact diverts the substrate
      away from adenine/AMP salvage toward the inosine/hypoxanthine catabolic branch.
    action: REMOVE
    reason: Over-propagated pathway-network annotation that is at odds with ADA's biology.
      AMP salvage is carried out by adenine phosphoribosyltransferase and adenosine
      kinase; ADA is catabolic. Should be removed.
- term:
    id: GO:0046059
    label: dAMP catabolic process
  evidence_type: IEA
  original_reference_id: GO_REF:0000107
  qualifier: involved_in
  review:
    summary: Ensembl-Compara electronic transfer of dAMP catabolic process. ADA deaminates
      the deoxynucleoside 2'-deoxyadenosine, not directly the deoxynucleotide dAMP; the
      direct catalytic step on dAMP is carried out by other enzymes (e.g. 5'-nucleotidases,
      deoxynucleotide deaminases).
    action: MARK_AS_OVER_ANNOTATED
    reason: As for the AMP catabolic-process annotation, this is a broad involved_in
      pathway term rather than a direct-substrate claim. ADA participates downstream in
      dAMP catabolism (dAMP is dephosphorylated to 2'-deoxyadenosine, which ADA deaminates
      to 2'-deoxyinosine), so the term is not strictly wrong at the pathway level; it is a
      nonspecific, ortholog-transferred over-annotation and is marked as over-annotated
      rather than treated as a core function.
- term:
    id: GO:0046936
    label: 2'-deoxyadenosine deaminase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: enables
  review:
    summary: Electronic annotation (RHEA:28190) of 2'-deoxyadenosine deaminase activity.
      ADA hydrolytically deaminates 2'-deoxyadenosine to 2'-deoxyinosine; this activity
      is the physiologically critical one whose loss drives dATP accumulation in ADA-SCID.
    action: ACCEPT
    reason: Correct core molecular function alongside adenosine deaminase activity,
      supported by the second RHEA reaction and by experimental catalytic data.
    supported_by:
    - reference_id: file:human/ADA/ADA-uniprot.txt
      supporting_text: Catalyzes the hydrolytic deamination of adenosine and 2-
- term:
    id: GO:0006805
    label: xenobiotic metabolic process
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-9748784
  qualifier: involved_in
  review:
    summary: Reactome (Drug ADME) annotation reflecting ADA's deamination of nucleoside
      analog drugs, notably ribavirin (RBV -> RBV-COOH) and cordycepin. This is a
      pharmacologically important but incidental substrate promiscuity.
    action: KEEP_AS_NON_CORE
    reason: A genuine xenobiotic/drug-metabolism role arising from ADA's broad specificity
      for adenosine-like nucleosides, but secondary to its endogenous purine-catabolic
      function.
    supported_by:
    - reference_id: file:human/ADA/ADA-uniprot.txt
      supporting_text: responsible for the deamination of cordycepin
- term:
    id: GO:0043101
    label: purine-containing compound salvage
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-74217
  qualifier: involved_in
  review:
    summary: Reactome (Purine salvage pathway) TAS annotation. ADA participates in
      the purine salvage/interconversion network by converting adenosine and 2'-deoxyadenosine
      to their inosine counterparts, which are then further metabolized.
    action: ACCEPT
    reason: ADA is a bona fide participant in the purine salvage/interconversion pathway;
      this broader process term is accurate and reflects the enzyme's contribution
      to purine-containing compound turnover.
    supported_by:
    - reference_id: PMID:9361033
      supporting_text: the purine salvage enzyme adenosine deaminase
- term:
    id: GO:0005886
    label: plasma membrane
  evidence_type: IDA
  original_reference_id: GO_REF:0000052
  qualifier: located_in
  review:
    summary: Human Protein Atlas immunofluorescence localization to the plasma membrane,
      consistent with the ecto-ADA cell-surface pool tethered by CD26/DPP4.
    action: KEEP_AS_NON_CORE
    reason: Correct for the cell-surface (ecto-ADA) pool; a secondary localization
      relative to the dominant cytosolic activity.
    supported_by:
    - reference_id: PMID:11999881
      supporting_text: indicating surface expression of ADA
- term:
    id: GO:0004000
    label: adenosine deaminase activity
  evidence_type: IMP
  original_reference_id: PMID:26166670
  qualifier: enables
  review:
    summary: IMP annotation of adenosine deaminase activity from a study of the ADA1
      G22A (Asp8Asn/ADA*2) polymorphism in fertile vs infertile men, in which ADA
      isoenzyme activities were measured; the low-activity GA genotype had reduced
      ADA1 activity.
    action: ACCEPT
    reason: Supports the core adenosine deaminase activity of the human enzyme via
      genotype-linked measurement of ADA1 activity.
    supported_by:
    - reference_id: PMID:26166670
      supporting_text: the ADA1 activity with GG genotype was higher than GA carriers
        in all population
- term:
    id: GO:0046936
    label: 2'-deoxyadenosine deaminase activity
  evidence_type: IMP
  original_reference_id: PMID:9361033
  qualifier: enables
  review:
    summary: IMP annotation from characterization of ADASCID mutant alleles (Y97C,
      L106V) whose loss of ADA activity is measured, establishing the enzyme's deoxyadenosine-deaminase
      function via mutation-driven activity loss and toxic dATP/deoxyadenosine accumulation.
    action: ACCEPT
    reason: Loss-of-function mutations abolishing enzyme activity, coupled with accumulation
      of the deoxyadenosine substrate, directly support ADA's 2'-deoxyadenosine deaminase
      activity as a core function.
    supported_by:
    - reference_id: PMID:9361033
      supporting_text: directly with the accumulation of the toxic metabolites deoxyATP
        and deoxyadenosine
- term:
    id: GO:0019239
    label: deaminase activity
  evidence_type: EXP
  original_reference_id: PMID:2166947
  qualifier: enables
  review:
    summary: Experimental annotation to the general parent 'deaminase activity' from
      characterization of hot-spot ADASCID mutations (e.g. Arg76Trp) that alter mutant
      ADA enzyme activity. The specific activity is adenosine deaminase activity.
    action: MODIFY
    reason: Correct in essence but too general; the mutations characterized affect
      adenosine deaminase activity specifically and the term should be refined to GO:0004000.
    proposed_replacement_terms:
    - id: GO:0004000
      label: adenosine deaminase activity
    supported_by:
    - reference_id: PMID:2166947
      supporting_text: resulting in Arg76 to Trp
- term:
    id: GO:0019239
    label: deaminase activity
  evidence_type: EXP
  original_reference_id: PMID:2783588
  qualifier: enables
  review:
    summary: Experimental annotation to the general parent 'deaminase activity' from
      identification of the Pro297Gln mutation causing a heat-labile ADA in partial
      ADA deficiency. The specific activity is adenosine deaminase activity.
    action: MODIFY
    reason: Correct in essence but too general; refine to the specific adenosine deaminase
      activity term.
    proposed_replacement_terms:
    - id: GO:0004000
      label: adenosine deaminase activity
    supported_by:
    - reference_id: PMID:2783588
      supporting_text: replacement of a proline
- term:
    id: GO:0019239
    label: deaminase activity
  evidence_type: EXP
  original_reference_id: PMID:3182793
  qualifier: enables
  review:
    summary: Experimental annotation to the general parent 'deaminase activity'. Mutant
      ADA alleles (e.g. Arg101Trp, Arg211His, Ala329Val) expressed by transfection
      failed to produce functional enzyme, demonstrating loss of adenosine deaminase
      activity.
    action: MODIFY
    reason: Correct in essence but too general; refine to the specific adenosine deaminase
      activity term.
    proposed_replacement_terms:
    - id: GO:0004000
      label: adenosine deaminase activity
    supported_by:
    - reference_id: PMID:3182793
      supporting_text: they do not encode a
- term:
    id: GO:0019239
    label: deaminase activity
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-9754964
  qualifier: enables
  review:
    summary: Reactome TAS annotation (ADA deamidates ribavirin) to the general parent
      'deaminase activity'. The specific activity is adenosine deaminase activity acting
      on ribavirin, an adenosine analog.
    action: MODIFY
    reason: Correct in essence but too general; the underlying reaction is ADA's adenosine
      deaminase activity applied to a nucleoside-analog drug. Refine to GO:0004000.
    proposed_replacement_terms:
    - id: GO:0004000
      label: adenosine deaminase activity
    supported_by:
    - reference_id: file:human/ADA/ADA-uniprot.txt
      supporting_text: Catalyzes the hydrolytic deamination of adenosine and 2-
- term:
    id: GO:0014074
    label: response to purine-containing compound
  evidence_type: IDA
  original_reference_id: PMID:25644539
  qualifier: involved_in
  review:
    summary: IDA annotation (MGI) from a study of calcific aortic valve disease in
      which adenosine, generated by ecto-nucleotidases, drives valve-interstitial-cell
      mineralization through the A2a adenosine receptor; ADA is part of the extracellular
      adenosine-metabolizing machinery in this context.
    action: KEEP_AS_NON_CORE
    reason: A context-specific (disease-associated) response annotation downstream
      of ADA's role in extracellular adenosine handling; peripheral to the core catabolic
      function.
    supported_by:
    - reference_id: PMID:25644539
      supporting_text: adenosine stimulated the mineralization of
- term:
    id: GO:0046085
    label: adenosine metabolic process
  evidence_type: IDA
  original_reference_id: PMID:25644539
  qualifier: involved_in
  review:
    summary: IDA annotation (MGI) placing ADA in adenosine metabolism in the context
      of calcific aortic valve disease. Adenosine metabolic process is a valid broader
      parent of ADA's core adenosine catabolic activity.
    action: KEEP_AS_NON_CORE
    reason: Correct but broader than the more specific 'adenosine catabolic process'
      that captures ADA's defining role. Retained as accurate; the specific catabolic
      term is preferred for the core function.
    supported_by:
    - reference_id: PMID:25644539
      supporting_text: adenosine stimulated the mineralization of
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-9734745
  qualifier: located_in
  review:
    summary: Reactome TAS cytosolic localization (defective ADA does not deaminate
      (deoxy)adenosine). Consistent with the core cytosolic site of ADA activity.
    action: ACCEPT
    reason: Correct primary localization, redundant with the IBA/IEA/other Reactome
      cytosol annotations.
    supported_by:
    - reference_id: PMID:11772392
      supporting_text: an enzyme mainly localized in the cytosol but also found on
        the cell surface of monocytes
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-74241
  qualifier: located_in
  review:
    summary: Reactome TAS cytosolic localization (ADA catalyzes the deamination of
      (deoxy)adenosine). Consistent with the core cytosolic site of ADA activity.
    action: ACCEPT
    reason: Correct primary localization, redundant with the other cytosol annotations.
    supported_by:
    - reference_id: PMID:11772392
      supporting_text: an enzyme mainly localized in the cytosol but also found on
        the cell surface of monocytes
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: TAS
  original_reference_id: Reactome:R-HSA-9754964
  qualifier: located_in
  review:
    summary: Reactome TAS cytosolic localization (ADA deamidates ribavirin). Consistent
      with the core cytosolic site of ADA activity.
    action: ACCEPT
    reason: Correct primary localization, redundant with the other cytosol annotations.
    supported_by:
    - reference_id: PMID:11772392
      supporting_text: an enzyme mainly localized in the cytosol but also found on
        the cell surface of monocytes
- term:
    id: GO:0004000
    label: adenosine deaminase activity
  evidence_type: IDA
  original_reference_id: PMID:8894685
  qualifier: enables
  review:
    summary: IDA annotation from full genetic rescue of ADA-deficient mice by the human
      ADA gene, demonstrating that the human enzyme provides functional adenosine deaminase
      activity that complements murine ADA in all tissues.
    action: ACCEPT
    reason: In vivo functional complementation is strong support that the human protein
      carries out adenosine deaminase activity; the lethal ADA-deficient phenotype
      is due to absence of the enzyme.
    supported_by:
    - reference_id: PMID:8894685
      supporting_text: human ADA can complement murine ADA in
- term:
    id: GO:0006154
    label: adenosine catabolic process
  evidence_type: IDA
  original_reference_id: PMID:8894685
  qualifier: acts_upstream_of_or_within
  review:
    summary: IDA annotation that ADA acts upstream of or within adenosine catabolism,
      from mouse genetic rescue showing the lethal ADA-deficient phenotype is corrected
      by restoring ADA function.
    action: ACCEPT
    reason: The rescue of ADA-deficient mice by the human gene confirms ADA's role
      in adenosine catabolism in vivo; this is the core biological process.
    supported_by:
    - reference_id: PMID:8894685
      supporting_text: lethal phenotype of ADA-deficient mice is due to the absence
- term:
    id: GO:0046103
    label: inosine biosynthetic process
  evidence_type: IDA
  original_reference_id: PMID:8894685
  qualifier: acts_upstream_of_or_within
  review:
    summary: IDA annotation that ADA acts upstream of or within inosine biosynthesis;
      inosine is the direct product of adenosine deamination, restored upon complementation
      of ADA-deficient mice by the human gene.
    action: ACCEPT
    reason: ADA directly generates inosine; valid process annotation downstream of
      the core catalytic reaction, supported by in vivo complementation.
    supported_by:
    - reference_id: PMID:8894685
      supporting_text: restoration of viability through introduction of the
- term:
    id: GO:0004000
    label: adenosine deaminase activity
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: enables
  review:
    summary: Sequence-similarity (ISS from mouse P03958) transfer of the core adenosine
      deaminase activity. Redundant with the directly demonstrated human activity.
    action: ACCEPT
    reason: Correct core molecular function, well supported by experimental data for
      the human enzyme.
    supported_by:
    - reference_id: file:human/ADA/ADA-uniprot.txt
      supporting_text: Catalyzes the hydrolytic deamination of adenosine and 2-
- term:
    id: GO:0006154
    label: adenosine catabolic process
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: involved_in
  review:
    summary: Sequence-similarity (ISS) transfer of the core adenosine catabolic process.
      Redundant with experimentally supported annotations.
    action: ACCEPT
    reason: Correct core biological process.
    supported_by:
    - reference_id: file:human/ADA/ADA-uniprot.txt
      supporting_text: Plays an important role in purine
- term:
    id: GO:0008270
    label: zinc ion binding
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: enables
  review:
    summary: Sequence-similarity (ISS) transfer of zinc ion binding. ADA binds one
      catalytic zinc per subunit; conserved across the family and required for catalysis.
    action: ACCEPT
    reason: Correct core cofactor-binding function, supported by structure and by disease
      mutations affecting zinc-coordinating residues.
    supported_by:
    - reference_id: file:human/ADA/ADA-uniprot.txt
      supporting_text: Binds 1 zinc ion per subunit
- term:
    id: GO:0046103
    label: inosine biosynthetic process
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: involved_in
  review:
    summary: Sequence-similarity (ISS) transfer of inosine biosynthetic process; inosine
      is the direct product of ADA-catalyzed adenosine deamination.
    action: ACCEPT
    reason: Valid process downstream of the core catalytic reaction.
    supported_by:
    - reference_id: PMID:8452534
      supporting_text: the conversion of [3H]adenosine into [3H]inosine was proportional
        to incubation time
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:8101391
  qualifier: enables
  review:
    summary: IPI documenting the direct, specific association of ADA with CD26/DPP4
      (P27487) on the T-cell surface, through the extracellular domain of CD26. This
      is the physiologically important ecto-ADA anchoring interaction.
    action: MARK_AS_OVER_ANNOTATED
    reason: The interaction itself is real and biologically important, but the term
      'protein binding' is uninformative. The functional consequences of the ADA-CD26
      interaction are already captured by the T-cell activation and cell-adhesion process
      annotations; the bare MF term is not retained as informative, though the IPI
      is not removed.
    supported_by:
    - reference_id: PMID:8101391
      supporting_text: an in vitro binding assay showed that the binding was through
        the extracellular domain of CD26
- term:
    id: GO:0004000
    label: adenosine deaminase activity
  evidence_type: IDA
  original_reference_id: PMID:11999881
  qualifier: enables
  review:
    summary: IDA annotation from a study of anti-ADA autoantibodies in lupus, which
      used purified/commercial ADA and detected ADA (the ADA1 40 kDa component) on
      cells; supports the identity and activity of the human ADA protein.
    action: ACCEPT
    reason: Consistent with the well-established core adenosine deaminase activity of
      human ADA1.
    supported_by:
    - reference_id: PMID:11999881
      supporting_text: corresponding to ADA1, the major component
    - reference_id: file:human/ADA/ADA-uniprot.txt
      supporting_text: Catalyzes the hydrolytic deamination of adenosine and 2-
- term:
    id: GO:0016020
    label: membrane
  evidence_type: IDA
  original_reference_id: PMID:11999881
  qualifier: located_in
  review:
    summary: IDA annotation to the very general term 'membrane', from immunofluorescence
      showing anti-ADA antibodies stain the cell surface of HEp-2 cells and lymphocytes.
      The staining reflects the ecto-ADA (cell-surface) pool.
    action: MODIFY
    reason: The generic 'membrane' term under-specifies the observation; the data show
      cell-surface/plasma-membrane localization of ecto-ADA. Refine to cell surface.
    proposed_replacement_terms:
    - id: GO:0009986
      label: cell surface
    supported_by:
    - reference_id: PMID:11999881
      supporting_text: surface of HEp-2 cells and lymphocytes, indicating surface expression
        of ADA
- term:
    id: GO:0001666
    label: response to hypoxia
  evidence_type: IDA
  original_reference_id: PMID:16670267
  qualifier: involved_in
  review:
    summary: IDA annotation that ADA participates in the hypoxia response; endothelial
      ADA (and its partner CD26) are induced by hypoxia at mRNA and protein levels,
      localizing ADA activity to the cell surface to clear elevated extracellular adenosine.
    action: KEEP_AS_NON_CORE
    reason: A genuine, experimentally demonstrated regulatory response (hypoxia-induced
      ADA/CD26), but a physiological/context-specific role secondary to the core catabolic
      function.
    supported_by:
    - reference_id: PMID:16670267
      supporting_text: hypoxia induces endothelial ADA and CD26
- term:
    id: GO:0004000
    label: adenosine deaminase activity
  evidence_type: IDA
  original_reference_id: PMID:16670267
  qualifier: enables
  review:
    summary: IDA annotation of adenosine deaminase activity; the study confirmed induction
      of enzymatically active ADA in hypoxic endothelium, degrading extracellular adenosine
      to inosine.
    action: ACCEPT
    reason: Directly demonstrated core adenosine deaminase activity of the human enzyme.
    supported_by:
    - reference_id: PMID:16670267
      supporting_text: increasing the endothelial capacity to metabolize adenosine
        to inosine
- term:
    id: GO:0004000
    label: adenosine deaminase activity
  evidence_type: IDA
  original_reference_id: PMID:8452534
  qualifier: enables
  review:
    summary: IDA annotation of adenosine deaminase activity, from direct assay of ADA
      activity (adenosine to inosine, Km 37 uM) in purified human fibroblast lysosomes.
    action: ACCEPT
    reason: Direct biochemical demonstration of the core adenosine deaminase activity
      of the human enzyme.
    supported_by:
    - reference_id: PMID:8452534
      supporting_text: the conversion of [3H]adenosine into [3H]inosine was proportional
        to incubation time
- term:
    id: GO:0004000
    label: adenosine deaminase activity
  evidence_type: IDA
  original_reference_id: PMID:9361033
  qualifier: enables
  review:
    summary: IDA annotation of adenosine deaminase activity from expression of wild-type
      and mutant ADA cDNAs; the Y97C mutant retained only detectable but markedly reduced
      activity, and wild-type ADA showed normal activity.
    action: ACCEPT
    reason: Directly measured expressed ADA activity supports the core adenosine deaminase
      function.
    supported_by:
    - reference_id: PMID:9361033
      supporting_text: detectable but markedly reduced activity
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:14684150
  qualifier: enables
  review:
    summary: IPI from a cryo-EM 3D structure of the CD26-ADA complex (partner P27487/DPP4),
      mapping the ADA-binding site across CD26 beta-propeller blades 4 and 5. Documents
      the specific ADA-CD26 interaction.
    action: MARK_AS_OVER_ANNOTATED
    reason: Real, structurally characterized ADA-CD26 interaction, but 'protein binding'
      is uninformative as a molecular function; the interaction's biological role is
      captured by the ecto-ADA process annotations. IPI retained, not removed.
    supported_by:
    - reference_id: PMID:14684150
      supporting_text: ADA binding occurs at the outer edges of the
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:7594462
  qualifier: enables
  review:
    summary: IPI documenting the ADA-CD26 (P27487) interaction on the T-cell surface,
      where ADA and CD26 colocalize and exogenous ADA produces an enzyme-independent
      costimulatory synergism in T-cell activation.
    action: MARK_AS_OVER_ANNOTATED
    reason: Genuine, functionally important ADA-CD26 interaction, but 'protein binding'
      is uninformative; the costimulatory role is captured by the T-cell activation
      process annotation. IPI retained, not removed.
    supported_by:
    - reference_id: PMID:7594462
      supporting_text: addition of ADA produced an enzyme-independent synergism
- term:
    id: GO:0005764
    label: lysosome
  evidence_type: IDA
  original_reference_id: PMID:8452534
  qualifier: located_in
  review:
    summary: IDA localization to the lysosome, from direct demonstration of ADA activity
      in Percoll-purified human fibroblast lysosomes (~10% of total cellular ADA activity).
    action: KEEP_AS_NON_CORE
    reason: Genuine but minor secondary localization relative to the dominant cytosolic
      pool.
    supported_by:
    - reference_id: PMID:8452534
      supporting_text: adenosine deaminase (ADA) activity that accounts for approximately
        10% of the total ADA activity
- term:
    id: GO:0006154
    label: adenosine catabolic process
  evidence_type: IDA
  original_reference_id: PMID:16670267
  qualifier: involved_in
  review:
    summary: IDA annotation of adenosine catabolic process; hypoxia-induced endothelial
      ADA (with CD26) increases the capacity to catabolize extracellular adenosine
      to inosine.
    action: ACCEPT
    reason: Direct demonstration of ADA's core biological process (adenosine catabolism)
      in a physiological setting.
    supported_by:
    - reference_id: PMID:16670267
      supporting_text: increasing the endothelial capacity to metabolize adenosine
        to inosine
- term:
    id: GO:0009897
    label: external side of plasma membrane
  evidence_type: IDA
  original_reference_id: PMID:16670267
  qualifier: located_in
  review:
    summary: IDA localization of ecto-ADA to the external side of the plasma membrane,
      tethered by CD26; surface binding was blocked by HIV gp120, which competes for
      ADA-CD26 binding.
    action: KEEP_AS_NON_CORE
    reason: Genuine cell-surface (extracellular) localization of the ecto-ADA pool;
      secondary to the dominant cytosolic activity.
    supported_by:
    - reference_id: PMID:16670267
      supporting_text: ADA localizes to the endothelial surface and limits the accumulation
        of extracellular adenosine during hypoxia
- term:
    id: GO:0009897
    label: external side of plasma membrane
  evidence_type: IDA
  original_reference_id: PMID:7759315
  qualifier: located_in
  review:
    summary: IDA localization of surface ADA on the plasma membrane of mononuclear
      blood cells detected by flow cytometry; surface ADA is a proposed B-cell marker
      in chronic lymphocytic leukemia.
    action: KEEP_AS_NON_CORE
    reason: Genuine cell-surface (ecto-ADA) localization; secondary to the dominant
      cytosolic pool.
    supported_by:
    - reference_id: PMID:7759315
      supporting_text: surface ADA might be considered a novel marker for CLL
- term:
    id: GO:0009986
    label: cell surface
  evidence_type: IDA
  original_reference_id: PMID:11772392
  qualifier: located_in
  review:
    summary: IDA localization of ADA to the cell surface, where cell-surface ADA (e.g.
      on Caco-2 epithelial cells) participates in ADA-CD26-mediated lymphocyte-epithelial
      adhesion.
    action: KEEP_AS_NON_CORE
    reason: Genuine ecto-ADA cell-surface localization; secondary to the core cytosolic
      pool.
    supported_by:
    - reference_id: PMID:11772392
      supporting_text: an enzyme mainly localized in the cytosol but also found on
        the cell surface of monocytes
- term:
    id: GO:0009986
    label: cell surface
  evidence_type: IDA
  original_reference_id: PMID:7594462
  qualifier: located_in
  review:
    summary: IDA localization of surface ADA on activated human T cells (flow cytometry),
      where ADA colocalizes with CD26 on the T-cell surface.
    action: KEEP_AS_NON_CORE
    reason: Genuine ecto-ADA cell-surface localization on lymphocytes; secondary to
      the core cytosolic pool.
    supported_by:
    - reference_id: PMID:7594462
      supporting_text: colocalized on the surface of T cells
- term:
    id: GO:0032261
    label: purine nucleotide salvage
  evidence_type: IMP
  original_reference_id: PMID:9361033
  qualifier: involved_in
  review:
    summary: IMP annotation placing ADA in purine nucleotide salvage; loss-of-function
      ADA mutations disrupt purine interconversion and cause toxic (deoxy)adenosine/dATP
      accumulation. ADA is described as a purine salvage enzyme.
    action: KEEP_AS_NON_CORE
    reason: ADA participates in the broader purine salvage/interconversion network,
      but its own committed reaction is adenosine catabolism (the core process). Retained
      as an accurate pathway-level annotation.
    supported_by:
    - reference_id: PMID:9361033
      supporting_text: the purine salvage enzyme adenosine deaminase
- term:
    id: GO:0033632
    label: regulation of cell-cell adhesion mediated by integrin
  evidence_type: IDA
  original_reference_id: PMID:11772392
  qualifier: involved_in
  review:
    summary: IDA annotation from experiments showing the ADA-CD26 interaction regulates
      lymphocyte-epithelial cell adhesion, with exogenous ADA increasing expression
      of activated integrins on T-cell lines (integrin activation assays).
    action: KEEP_AS_NON_CORE
    reason: A genuine extra-enzymatic (moonlighting) role of ecto-ADA via CD26 in modulating
      integrin-mediated cell adhesion; secondary to the core catabolic function.
    supported_by:
    - reference_id: PMID:11772392
      supporting_text: FACS analysis revealed a higher expression of activated
- term:
    id: GO:0042110
    label: T cell activation
  evidence_type: IDA
  original_reference_id: PMID:7594462
  qualifier: involved_in
  review:
    summary: IDA annotation that ADA acts in T cell activation; exogenous ADA binding
      to CD26 produces a costimulatory (enzyme-independent) synergism in the TCR-CD3
      activation response.
    action: KEEP_AS_NON_CORE
    reason: A genuine moonlighting immunological role of ecto-ADA via CD26, distinct
      from and secondary to the core cytosolic catalytic function.
    supported_by:
    - reference_id: PMID:7594462
      supporting_text: binding to CD26 produces a costimulatory response in T cell
        activation events
- term:
    id: GO:0060169
    label: negative regulation of adenosine receptor signaling pathway
  evidence_type: IDA
  original_reference_id: PMID:16670267
  qualifier: involved_in
  review:
    summary: IDA annotation that ADA negatively regulates adenosine-receptor signaling
      by clearing extracellular adenosine (the receptor agonist), limiting adenosine
      accumulation and downstream signaling in hypoxic endothelium.
    action: KEEP_AS_NON_CORE
    reason: A genuine signaling consequence of ecto-ADA's extracellular adenosine clearance,
      secondary to the core catabolic activity. Context-dependent, since ADA can also
      positively modulate adenosine-receptor agonist affinity.
    supported_by:
    - reference_id: PMID:16670267
      supporting_text: ADA localizes to the endothelial surface and limits the accumulation
        of extracellular adenosine during hypoxia
- term:
    id: GO:0004000
    label: adenosine deaminase activity
  evidence_type: IDA
  original_reference_id: PMID:3182793
  qualifier: enables
  review:
    summary: IDA annotation of adenosine deaminase activity; wild-type ADA cDNA expressed
      by transfection produced ADA enzymatic levels ~40-fold higher than mutant sequences,
      confirming the enzyme's catalytic activity.
    action: ACCEPT
    reason: Directly measured expressed ADA enzyme activity supports the core adenosine
      deaminase function; mutant alleles failed to encode functional enzyme.
    supported_by:
    - reference_id: PMID:3182793
      supporting_text: they do not encode a
- term:
    id: GO:0008270
    label: zinc ion binding
  evidence_type: IMP
  original_reference_id: PMID:7599635
  qualifier: enables
  review:
    summary: IMP annotation of zinc ion binding from the ADASCID His15Asp mutation,
      the first naturally occurring mutation of a residue that directly coordinates
      the enzyme-associated zinc ion; H15D abolishes ADA activity.
    action: ACCEPT
    reason: A disease mutation of a direct zinc-coordinating residue that abolishes
      activity provides strong functional evidence for ADA's core zinc-binding cofactor
      role.
    supported_by:
    - reference_id: PMID:7599635
      supporting_text: the first naturally occurring mutation of a residue that coordinates
core_functions:
- description: Zinc-dependent hydrolytic deamination of adenosine to inosine and of
    2'-deoxyadenosine to 2'-deoxyinosine, the committed catabolic step that clears
    (deoxy)adenosine and maintains adenosine/purine homeostasis. Loss of this activity
    causes toxic (deoxy)adenosine and dATP accumulation and ADA-SCID.
  molecular_function:
    id: GO:0004000
    label: adenosine deaminase activity
  directly_involved_in:
  - id: GO:0006154
    label: adenosine catabolic process
  locations:
  - id: GO:0005829
    label: cytosol
  substrates:
  - id: CHEBI:16335
    label: adenosine
  - id: CHEBI:17256
    label: 2'-deoxyadenosine
  supported_by:
  - reference_id: file:human/ADA/ADA-uniprot.txt
    supporting_text: Catalyzes the hydrolytic deamination of adenosine and 2-
  - reference_id: PMID:8452534
    supporting_text: the conversion of [3H]adenosine into [3H]inosine was proportional
      to incubation time
- description: 2'-deoxyadenosine deaminase activity; hydrolytic deamination of the
    deoxynucleoside 2'-deoxyadenosine to 2'-deoxyinosine. This is the physiologically
    critical activity in lymphocytes, since its loss drives dATP accumulation underlying
    ADA-SCID.
  molecular_function:
    id: GO:0046936
    label: 2'-deoxyadenosine deaminase activity
  directly_involved_in:
  - id: GO:0006154
    label: adenosine catabolic process
  locations:
  - id: GO:0005829
    label: cytosol
  supported_by:
  - reference_id: PMID:9361033
    supporting_text: directly with the accumulation of the toxic metabolites deoxyATP
      and deoxyadenosine
- description: Catalytic zinc-ion binding cofactor function. Each ADA subunit binds
    one Zn2+ coordinated by conserved histidine and aspartate residues; the zinc activates
    a water molecule for nucleophilic attack and is required for deaminase catalysis.
  molecular_function:
    id: GO:0008270
    label: zinc ion binding
  locations:
  - id: GO:0005829
    label: cytosol
  supported_by:
  - reference_id: file:human/ADA/ADA-uniprot.txt
    supporting_text: Binds 1 zinc ion per subunit
  - reference_id: PMID:7599635
    supporting_text: the first naturally occurring mutation of a residue that coordinates
references:
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO
    terms
  findings: []
- id: GO_REF:0000024
  title: Manual transfer of experimentally-verified manual GO annotation data to orthologs
    by curator judgment of sequence similarity
  findings: []
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location
    vocabulary mapping, accompanied by conservative changes to GO terms applied by
    UniProt
  findings: []
- id: GO_REF: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:0000117
  title: Electronic Gene Ontology annotations created by ARBA machine learning models
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:11772392
  title: Regulation of epithelial and lymphocyte cell adhesion by adenosine deaminase-CD26
    interaction.
  findings: []
- id: PMID:11999881
  title: Anti-adenosine deaminase antibodies in lupus erythematosus.
  findings: []
- id: PMID:14684150
  title: 3D structure of the CD26-ADA complex obtained by cryo-EM and single particle
    analysis.
  findings: []
- id: PMID:16670267
  title: 'Endothelial catabolism of extracellular adenosine during hypoxia: the role
    of surface adenosine deaminase and CD26.'
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Full text available; directly demonstrates hypoxia-induced ecto-ADA/CD26
      catabolizing extracellular adenosine to inosine. Supports the ecto-ADA localization,
      adenosine catabolic process, and hypoxia-response annotations.
- id: PMID:2166947
  title: Hot spot mutations in adenosine deaminase deficiency.
  findings: []
- id: PMID:25644539
  title: Adenosine derived from ecto-nucleotidases in calcific aortic valve disease
    promotes mineralization through A2a adenosine receptor.
  findings: []
- id: PMID:26166670
  title: The Role of G22 A Adenosine Deaminase 1 Gene Polymorphism and the Activities
    of ADA Isoenzymes in Fertile and Infertile Men.
  findings: []
- id: PMID:2783588
  title: Identification of a point mutation resulting in a heat-labile adenosine deaminase
    (ADA) in two unrelated children with partial ADA deficiency.
  findings: []
- id: PMID:28514442
  title: Architecture of the human interactome defines protein communities and disease
    networks.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: Proteome-scale AP-MS interactome (BioPlex). Source of a bare 'protein
      binding' IPI to POTEF; correctly cited but not functionally informative for ADA.
- id: PMID:3182793
  title: Mutant human adenosine deaminase alleles and their expression by transfection
    into fibroblasts.
  findings: []
- id: PMID:33961781
  title: Dual proteome-scale networks reveal cell-specific remodeling of the human
    interactome.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: Proteome-scale interactome dataset; source of a bare 'protein binding'
      IPI to POTEF. Correctly cited but not functionally informative for ADA.
- id: PMID:7594462
  title: Expression of ecto-adenosine deaminase and CD26 in human T cells triggered
    by the TCR-CD3 complex. Possible role of adenosine deaminase as costimulatory
    molecule.
  findings: []
- id: PMID:7599635
  title: Four new adenosine deaminase mutations, altering a zinc-binding histidine,
    two conserved alanines, and a 5' splice site.
  findings: []
- id: PMID:7759315
  title: Surface adenosine deaminase. A novel B-cell marker in chronic lymphocytic
    leukemia.
  findings: []
- id: PMID:8101391
  title: Direct association of adenosine deaminase with a T cell activation antigen,
    CD26.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Foundational paper establishing the specific ADA-CD26/DPP4 interaction
      via the CD26 extracellular domain. Underpins the ecto-ADA/CD26 (moonlighting)
      annotations; the bare 'protein binding' MF is uninformative and marked over-annotated.
- id: PMID:8452534
  title: Demonstration of adenosine deaminase activity in human fibroblast lysosomes.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Direct biochemical assay of human ADA activity (adenosine->inosine,
      Km 37 uM) and demonstration of a minor lysosomal pool (~10% of total activity).
      Supports the core MF and the lysosome localization.
- id: PMID:8894685
  title: Full genetic rescue of adenosine deaminase-deficient mice through introduction
    of the human gene.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: In vivo demonstration that the human ADA gene fully complements the
      lethal ADA-deficient mouse phenotype, confirming ADA's essential catabolic function.
- id: PMID:9361033
  title: An adenosine deaminase (ADA) allele contains two newly identified deleterious
    mutations (Y97C and L106V) that interact to abolish enzyme activity.
  findings: []
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Characterizes ADASCID loss-of-function mutations and the link between
      loss of activity and toxic deoxyATP/deoxyadenosine accumulation. Supports the
      core adenosine/deoxyadenosine deaminase functions and the disease mechanism.
- id: Reactome:R-HSA-74217
  title: Purine salvage
  findings: []
- id: Reactome:R-HSA-74241
  title: ADA catalyzes the deamination of (deoxy)adenosine
  findings: []
- id: Reactome:R-HSA-9734745
  title: Defective ADA does not deaminate (deoxy)adenosine
  findings: []
- id: Reactome:R-HSA-9748784
  title: Drug ADME
  findings: []
- id: Reactome:R-HSA-9754964
  title: ADA deamidates RBV
  findings: []
suggested_questions:
- question: Are the cell-surface (ecto-ADA), cytosolic, and lysosomal pools of ADA
    the product of a single gene/transcript, and how is surface localization (via
    CD26/DPP4) achieved given ADA lacks a signal peptide or transmembrane domain?
- question: To what extent are ADA's extra-enzymatic (moonlighting) roles in T-cell
    costimulation and cell adhesion mechanistically separable from its catalytic clearance
    of extracellular adenosine?
suggested_experiments:
- description: Catalytically-dead (e.g. zinc-site) ADA knock-in versus wild-type rescue
    in ADA-deficient lymphocytes to dissect enzyme-dependent versus CD26-binding (moonlighting)
    contributions to T-cell activation and adhesion.
- description: Quantitative subcellular fractionation plus surface biotinylation across
    cell types to measure the relative sizes of the cytosolic, lysosomal, and ecto-ADA
    pools and their dependence on CD26 expression.

Gene Description

Existing Annotations Review

Core Functions

Zinc-dependent hydrolytic deamination of adenosine to inosine and of 2'-deoxyadenosine to 2'-deoxyinosine, the committed catabolic step that clears (deoxy)adenosine and maintains adenosine/purine homeostasis. Loss of this activity causes toxic (deoxy)adenosine and dATP accumulation and ADA-SCID.

2'-deoxyadenosine deaminase activity; hydrolytic deamination of the deoxynucleoside 2'-deoxyadenosine to 2'-deoxyinosine. This is the physiologically critical activity in lymphocytes, since its loss drives dATP accumulation underlying ADA-SCID.

Catalytic zinc-ion binding cofactor function. Each ADA subunit binds one Zn2+ coordinated by conserved histidine and aspartate residues; the zinc activates a water molecule for nucleophilic attack and is required for deaminase catalysis.

References

Suggested Questions for Experts

Suggested Experiments

📚 Additional Documentation

Notes

ADA (human) — curation notes

Core biology

Localization

Annotation decisions (summary)

Sleep (GO:0045187)

📄 View Raw YAML