ENPP1 is a type-II membrane ectoenzyme with extracellular nucleotide-hydrolyzing domains and a soluble processed form. It converts extracellular ATP to AMP and inorganic pyrophosphate, thereby controlling mineral deposition in bone and soft tissues. ENPP1 also hydrolyzes extracellular cyclic GMP–AMP, influencing the availability of this intercellular immune signal. Its catalytic architecture contains zinc ions and a separate calcium-binding structural domain. Protein interactions and expression-dependent effects on insulin signaling, adipocyte maturation and pigmentation have been observed in specific cell and disease contexts.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003676 nucleic acid binding | IEA GO_REF:0000002 | UNDECIDED | Summary: The nuclease-like domains are present, but their mapping does not by itself establish ENPP1 nucleic-acid binding. Reason: Official InterPro IPR001604/IPR020821 matches establish domain identity. PMID:23027977 identifies the nuclease-like fold and its calcium site, without a nucleic-acid-binding assay. PMID:22285541 explicitly reports ENPP1 oligoadenylate degradation in its abstract, so binding cannot be rejected on fold naming; the operative original and ENPP1-specific substrate assay remain unavailable. Supporting Evidence: GO_REF:0000002 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0004115 3',5'-cyclic-AMP phosphodiesterase activity | EXP PMID:28011303 The promiscuous ectonucleotidase NPP1: molecular insights in... | UNDECIDED | Summary: Cyclic-AMP hydrolysis remains unresolved in the inaccessible original assay. Reason: PMID:28011303 has a bibliography-only normal cache. The separately retrieved ScienceDirect abstract and section previews at https://doi.org/10.1016/j.bbagen.2016.12.019 describe biochemical experiments combined with homology modeling and docking; complete Methods, the protein preparation and Table 1 were not recovered. The indexed abstract names cAMP, but it is not sufficient to verify the source-specific assay or assign kinetics to a natural human product. Retain UNDECIDED pending operative assay evidence; there is no contradiction justifying removal. |
| GO:0004115 3',5'-cyclic-AMP phosphodiesterase activity | IEA GO_REF:0000116 | UNDECIDED | Summary: The Rhea reaction matches the cyclic-AMP term, but the ENPP1-specific cyclic-AMP assay remains unresolved. Reason: The official RHEA:25277 equation is cyclic AMP hydrolysis to AMP, so the chemical mapping is correct. PMID:28011303 was not recovered beyond abstract-level information. ATP and cyclic dinucleotide assays do not substitute for this distinct cyclic mononucleotide reaction. |
| GO:0004527 exonuclease activity | IDA PMID:22285541 Characterization of human phosphodiesterase 12 and identific... | UNDECIDED | Summary: ENPP1 is explicitly implicated in oligoadenylate degradation, but the exact exonuclease experiment remains unresolved. Reason: The verified PMID:22285541 abstract explicitly identifies human ENPP1 as an oligoadenylate nuclease, so this is not a wrong-gene reference. The ENPP1-specific experiments, substrate directionality, constructs and controls were not accessible. Exonuclease specificity cannot be independently resolved from the PDE12-focused kinetic description; retain uncertainty pending the original ENPP1 assays. |
| GO:0004528 phosphodiesterase I activity | EXP PMID:8001561 Biochemical characterization of human PC-1, an enzyme posses... | UNDECIDED | Summary: Specific oligonucleotide phosphodiesterase-I activity remains unresolved in the recovered source scope. Reason: PMID:8001561 Methods p. 436 assays a synthetic phosphonate, whereas current GO:0004528 specifies oligonucleotide exonucleolysis. The bounded original pages do not resolve this specificity. This is not evidence that the activity is absent; see the source guide. |
| GO:0004528 phosphodiesterase I activity | IBA GO_REF:0000033 | UNDECIDED | Summary: PAINT records an inherited phosphodiesterase-I assertion, whose exact oligonucleotide specificity remains unresolved here. Reason: The cached PTHR10151 IBD at PTN002562515 explicitly carries GO:0004528 with mouse, rat and human descendant evidence. This is not circular and donor count is not a weakness. Current GO defines sequential 3-prime-terminal oligonucleotide hydrolysis. The read human and mouse assays use synthetic phosphonate or pNP-TMP substrates, and the exact mouse donor originals listed by QuickGO/UniProt (PMID:11027689, PMID:1647027, PMID:8223581 and others) were not read. ENPP1 oligoadenylate activity is explicitly reported by the unavailable PMID:22285541 original. Retain uncertainty about the exact reaction, not a claim of erroneous phylogenetic placement or absent nuclease activity. Supporting Evidence: GO_REF:0000033 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0004528 phosphodiesterase I activity | IDA PMID:27467858 Effects of Different Variants in the ENPP1 Gene on the Funct... | UNDECIDED | Summary: The accessible abstract reports ENPP1 variant activity measurements, but the substrate and assay supporting the oligonucleotide-defined term could not be checked. Reason: PMID:27467858 was recovered only as an abstract; publisher full text and supplement were inaccessible. GO:0004528 denotes sequential nucleotide removal from oligonucleotide termini. General NPP activity or ATP hydrolysis does not independently verify that exact reaction. Retain uncertainty without contradicting the experimental curator. |
| GO:0004528 phosphodiesterase I activity | IEA GO_REF:0000120 | UNDECIDED | Summary: The ARBA and EC mappings assert phosphodiesterase I, but the exact oligonucleotide reaction remains unresolved. Reason: ARBA00088592 was recovered and its three FunFam conditions match the human UniProt record; EC:3.1.4.1 maps to the current oligonucleotide-defined GO term. Verified rule matching is not independent substrate evidence. The recovered synthetic-substrate assays and unread oligoadenylate original leave the exact terminal-removal reaction unresolved. Supporting Evidence: GO_REF:0000120 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0004528 phosphodiesterase I activity | ISS GO_REF:0000024 | UNDECIDED | Summary: The mouse ortholog has curated phosphodiesterase-I evidence, but its exact oligonucleotide substrate experiments were not assessed. Reason: UniProtKB:P06802 is verified mouse Enpp1, and its catalytic record cites PMID:11027689, PMID:1647027 and PMID:8223581 for the oligonucleotide reaction. Those operative originals were not recovered in this review. PMID:23027977 pNP-TMP hydrolysis does not independently establish sequential oligonucleotide cleavage; the positive ENPP1 oligoadenylate abstract of PMID:22285541 also prevents an absence claim. Supporting Evidence: GO_REF:0000024 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0004551 dinucleotide phosphatase activity | IBA GO_REF:0000033 | UNDECIDED | Summary: The inherited dinucleotide-phosphatase assertion requires acid-anhydride substrate evidence not established by the read cGAMP assays. Reason: The cached PAINT IBD at PTN002562515 carries GO:0004551 with human and mouse descendant support. Current ontology ancestry places it under pyrophosphatase and acid-anhydride hydrolysis. The read cGAMP originals establish phosphodiester cleavage, so their two mononucleotide products do not independently establish this reaction class. Reactome records FAD hydrolysis, but the corresponding original FAD/NAD or dinucleotide-pyrophosphate assay was not independently verified. Retain uncertainty without challenging the phylogenetic node or denying the enzyme’s established ATP/cGAMP activities. Supporting Evidence: GO_REF:0000033 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0004551 dinucleotide phosphatase activity | IDA PMID:12746903 One of two chondrocyte-expressed isoforms of cartilage inter... | UNDECIDED | Summary: The source-specific dinucleotide-phosphatase reaction remains unresolved. Reason: The operative PMID:12746903 original remains inaccessible; its CILP-centered abstract neither verifies the comparator assay nor establishes miscitation. GO:0004551 has acid-anhydride-hydrolysis ancestry. Independently read cGAMP cleavage concerns phosphodiester bonds and does not establish the required dinucleotide-pyrophosphate reaction merely because two mononucleotides are produced. The Reactome FAD mapping was not independently confirmed against an operative original substrate assay. Supporting Evidence: file:human/ENPP1/ENPP1-source-guide.md |
| GO:0005044 scavenger receptor activity | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: A somatomedin-B domain match does not establish scavenger-receptor activity for ENPP1. Reason: IPR020436 genuinely matches ENPP1, but its generic GO mapping requires binding a polyanionic ligand and delivering it into the cell by endocytosis. The actual ENPP1 SMB evidence concerns oligomerization and protein interaction; neither that work nor the original targeting study demonstrates this ligand-delivery function. Mark the functional extrapolation as over-annotated without denying the domain match or all possible internalization. Supporting Evidence: GO_REF:0000002 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0005158 insulin receptor binding | IDA PMID:7830796 Membrane glycoprotein PC-1 and insulin resistance in non-ins... | KEEP AS NON CORE | Summary: ENPP1 associates with the insulin receptor in the tested human cell systems. Reason: The operative PMID:7830796 original remains inaccessible. Independently read PMID:11289049 Figs. 2–3 demonstrates ENPP1–INSR association by receptor capture and co-immunoprecipitation. Retain receptor binding as a supported non-core interaction; this does not claim a purified binary affinity measurement or verify the unread 1995 experiment. |
| GO:0005509 calcium ion binding | ISS GO_REF:0000024 | ACCEPT | Summary: The conserved extracellular enzyme contains a calcium-binding structural site. Reason: The verified donor is mouse Enpp1. PMID:23027977, Nuclease-Like Domain section, identifies a calcium ion coordinated by an EF-hand-like motif; this supports the ortholog transfer. The site is separate from the catalytic zinc ions. Mouse residue coordinates are not assigned directly to human ENPP1. |
| GO:0005515 protein binding | IPI PMID:11289049 The Q allele variant (GLN121) of membrane glycoprotein PC-1 ... | MODIFY | Summary: Specify the experimentally identified insulin-receptor interaction. Reason: PMID:11289049 (doi:10.2337/diabetes.50.4.831), PC-1–IR interaction Methods and Figs. 2–3, identifies the partner as INSR/P06213 by receptor capture and co-immunoprecipitation of human ENPP1 in MCF-7 cells. GO:0005158 insulin receptor binding is therefore more informative than generic protein binding and is independently used to retain the existing receptor-binding annotation. This refinement does not claim purified binary affinity or make the interaction a core catalytic function. Proposed replacements: insulin receptor binding |
| GO:0005515 protein binding | IPI PMID:26065921 Loss of microRNA-27b contributes to breast cancer stem cell ... | KEEP AS NON CORE | Summary: ENPP1 physically associates with ABCG2 in the tested human cell systems. Reason: PMID:26065921, Results on ABCG2 surface localization, Fig. 6f,g and Supplementary Fig. 9, combines proximity ligation, affinity-purified protein binding and deletion/co-immunoprecipitation assays. The N-terminal ENPP1 region contributes to this interaction. Retain supported binding as non-core under campaign policy; these data do not establish a general transporter or adapter molecular function. |
| GO:0005524 ATP binding | IDA PMID:7830796 Membrane glycoprotein PC-1 and insulin resistance in non-ins... | ACCEPT | Summary: ATP interaction is inherent to the established ENPP1 ATP-hydrolysis reaction. Reason: PMID:7830796 was recovered only at abstract/landing-page level. Independently read PMID:8001561 pp. 437–438/Figs. 2–3 reports ATP-derived labeling of human PC-1, while PMID:23027977 directly establishes mouse ENPP1 ATP hydrolysis. Retain ATP binding as part of the catalytic function without presenting these studies as verification of the unread 1995 assay or claiming a measured human equilibrium affinity. |
| GO:0005576 extracellular region | IBA GO_REF:0000033 | ACCEPT | Summary: ENPP1 has extracellular catalytic domains and a soluble extracellular product. Reason: The cached PTN002562515 IBD carries extracellular location with human and mouse support. PMID:11159191 Methods and Fig. 2 detect soluble human plasma PC-1. The imported human record annotates a 103–925 processed chain by mouse similarity; this does not establish a human splice isoform or directly verify the human cleavage site. |
| GO:0005576 extracellular region | IDA PMID:11159191 PC-1 nucleoside triphosphate pyrophosphohydrolase deficiency... | ACCEPT | Summary: Soluble human PC-1/ENPP1 was detected in plasma. Reason: PMID:11159191 measured soluble PC-1 in human plasma by a PC-1-specific ELISA and found it in controls, with very low levels in the proband. This directly supports extracellular region as a location, without claiming that all ENPP1 is soluble or specifying a natural isoform. |
| GO:0005576 extracellular region | IEA GO_REF:0000044 | ACCEPT | Summary: ENPP1 has extracellular catalytic domains and a soluble extracellular product. Reason: The UniProt SL-0243 mapping denotes secretion. PMID:11159191 Methods and Fig. 2 detect soluble human plasma PC-1. The imported human record annotates a 103–925 processed chain by mouse similarity; this does not establish a human splice isoform or directly verify the human cleavage site. |
| GO:0005576 extracellular region | ISS GO_REF:0000024 | ACCEPT | Summary: ENPP1 has extracellular catalytic domains and a soluble extracellular product. Reason: The verified donor P06802 has an annotated proteolytically secreted product. PMID:11159191 Methods and Fig. 2 detect soluble human plasma PC-1. The imported human record annotates a 103–925 processed chain by mouse similarity; this does not establish a human splice isoform or directly verify the human cleavage site. |
| GO:0005765 lysosomal membrane | HDA PMID:17897319 Integral and associated lysosomal membrane proteins. | UNDECIDED | Summary: The cited human placental lysosomal proteomics study was recovered, but its ENPP1-specific enrichment result remains unverified. Reason: PMID:17897319 distinguishes significantly enriched proteins from depleted or non-significant detections using comparative spectral counts. The ENPP1-specific Supplementary Table S3 entry was not recovered. The HDA localization remains unresolved; a missing accessible protein-level result is not evidence against the annotation. |
| GO:0005886 plasma membrane | EXP PMID:15072822 Expression and localization of ecto-nucleotide pyrophosphata... | ACCEPT | Summary: Plasma-membrane localization is independently established for human ENPP1. Reason: The operative PMID:15072822 original was not recovered; its source-specific images and controls remain unverified. Human PC-1 surface staining in PMID:8001561 p. 439/Fig. 4 and human valve-cell localization in PMID:25644539 independently establish the location. Retain the correct annotation and its original citation without claiming that the inaccessible experiment was read. Supporting Evidence: file:human/ENPP1/ENPP1-source-guide.md |
| GO:0005886 plasma membrane | EXP PMID:8001561 Biochemical characterization of human PC-1, an enzyme posses... | ACCEPT | Summary: Human ENPP1 is displayed at the cell surface. Reason: PMID:8001561 p. 439/Figure 4 shows surface staining of human PC-1 expressed in mouse Ltk− cells, with a negative vector control; p. 436 specifies the flow-cytometry method. |
| GO:0005886 plasma membrane | IBA GO_REF:0000033 | ACCEPT | Summary: ENPP1 is a cell-surface plasma-membrane enzyme. Reason: The imported IBA names PTN002562515. The pinned PAINT cache carries basolateral localization at this node, but no exact plasma-membrane IBD row; full tree retrieval failed. This cache difference is not treated as a biological contradiction or a fabricated node-placement result. Human PC-1 surface staining in PMID:8001561 p. 439/Fig. 4 and human valve-cell localization in PMID:25644539 independently support this location. Supporting Evidence: GO_REF:0000033 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0005886 plasma membrane | IDA PMID:10513816 Differential mechanisms of inorganic pyrophosphate productio... | ACCEPT | Summary: Plasma-membrane localization is independently established for human ENPP1. Reason: The operative PMID:10513816 original was not recovered; its source-specific images and controls remain unverified. Human PC-1 surface staining in PMID:8001561 p. 439/Fig. 4 and human valve-cell localization in PMID:25644539 independently establish the location. Retain the correct annotation and its original citation without claiming that the inaccessible experiment was read. Supporting Evidence: file:human/ENPP1/ENPP1-source-guide.md |
| GO:0005886 plasma membrane | IDA PMID:25644539 Adenosine derived from ecto-nucleotidases in calcific aortic... | ACCEPT | Summary: Human valve interstitial cells display NPP1 at the plasma membrane. Reason: PMID:25644539 reports confocal co-localization of NPP1 and the membrane marker WGA in human VICs. This directly supports the cellular location. The experiment is separate from the mouse A2a receptor knockout assays later in the article. |
| GO:0005886 plasma membrane | IDA PMID:27467858 Effects of Different Variants in the ENPP1 Gene on the Funct... | ACCEPT | Summary: Plasma-membrane localization is independently established for human ENPP1. Reason: The operative PMID:27467858 original was not recovered; its source-specific images and controls remain unverified. Human PC-1 surface staining in PMID:8001561 p. 439/Fig. 4 and human valve-cell localization in PMID:25644539 independently establish the location. Retain the correct annotation and its original citation without claiming that the inaccessible experiment was read. Supporting Evidence: file:human/ENPP1/ENPP1-source-guide.md |
| GO:0005886 plasma membrane | IEA GO_REF:0000120 | ACCEPT | Summary: ENPP1 is a cell-surface plasma-membrane enzyme. Reason: ARBA00027801 was recovered; an actual matching FunFam condition set and SL-0039 support the membrane-location mapping. Human PC-1 surface staining in PMID:8001561 p. 439/Fig. 4 and human valve-cell localization in PMID:25644539 independently support this location. Supporting Evidence: GO_REF:0000120 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0005886 plasma membrane | ISS GO_REF:0000024 | ACCEPT | Summary: ENPP1 is a cell-surface plasma-membrane enzyme. Reason: The verified P06802 donor is mouse Enpp1, whose membrane targeting was directly tested in PMID:11598187. Human PC-1 surface staining in PMID:8001561 p. 439/Fig. 4 and human valve-cell localization in PMID:25644539 independently support this location. Supporting Evidence: GO_REF:0000024 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0005886 plasma membrane | TAS Reactome:R-HSA-196955 | ACCEPT | Summary: ENPP1 is a cell-surface plasma-membrane enzyme. Reason: Reactome R-HSA-196955 places the ENPP1 catalyst at the plasma membrane; metabolite compartment labels are not evidence for cytosolic ENPP1. Human PC-1 surface staining in PMID:8001561 p. 439/Fig. 4 and human valve-cell localization in PMID:25644539 independently support this location. Supporting Evidence: Reactome:R-HSA-196955 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0006091 generation of precursor metabolites and energy | IDA PMID:12746903 One of two chondrocyte-expressed isoforms of cartilage inter... | UNDECIDED | Summary: PMID:12746903 original experimental evidence could not be accessed. Reason: The abstract focuses on CILP isoforms, their lack of NPP activity, and inhibition of IGF-1 responses. It does not resolve whether ENPP1 was assayed as a comparator or which experiment supports this annotation. The title and abstract are insufficient to reject a curator-read experimental annotation or assert wrong-gene attribution. Original assay evidence is needed. |
| GO:0006796 phosphate-containing compound metabolic process | IDA PMID:10513816 Differential mechanisms of inorganic pyrophosphate productio... | MODIFY | Summary: Nucleoside-triphosphate catabolism identifies the directly established phosphate-compound reaction. Reason: PMID:10513816 remains abstract-only, so its exact assays were not reviewed. Independent human PC-1 experiments in PMID:11159191 Fig. 9 establish NTPPPH activity and extracellular PPi generation, and PMID:23027977 establishes ATP-to-AMP/PPi chemistry in mouse enzyme. Replace the broad phosphate-compound metabolism term with the established NTP-catabolic process; this is a functional replacement, not a claim of a verified GO child relation. Proposed replacements: nucleoside triphosphate catabolic process Supporting Evidence: file:human/ENPP1/ENPP1-source-guide.md |
| GO:0006796 phosphate-containing compound metabolic process | IDA PMID:11159191 PC-1 nucleoside triphosphate pyrophosphohydrolase deficiency... | MODIFY | Summary: Human PC-1 directly supports nucleotide-triphosphate breakdown and PPi generation. Reason: PMID:11159191 connects human PC-1 expression to increased NTPPPH activity and extracellular PPi in human aortic smooth muscle cells (Figure 9), and to increased activity and PPi after proband fibroblast transfection (reported without displayed data). Nucleoside triphosphate catabolic process describes the enzymatic work more clearly than the broad phosphate-containing compound term. This is a functional replacement, not a claimed is_a descendant relationship in the captured current ontology. Proposed replacements: nucleoside triphosphate catabolic process |
| GO:0006955 immune response | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: ENPP1 nucleotide hydrolysis can regulate extracellular immune signaling. Reason: The broad IPR020436 immune-response mapping is not established merely by the SMB domain. Independent primary evidence supports the biological assertion: PMID:25344812 establishes native-cell/knockout ENPP1-dependent cGAMP destruction, and PMID:30356045 tests human THP-1 interferon reporter consequences. Retain immune response as a contextual consequence of extracellular enzymatic activity; do not infer a scavenger-receptor mechanism. Supporting Evidence: GO_REF:0000002 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0008270 zinc ion binding | ISS GO_REF:0000024 | ACCEPT | Summary: ENPP1 has a zinc-dependent catalytic site. Reason: P06802 is the verified mouse ortholog. PMID:23027977 Catalytic Domain section/Fig. 3 resolves two zinc ions around the catalytic center; PMID:30356045 independently supports the mouse catalytic architecture. This supports the ISS claim without transferring mouse residue numbering to the human product. Supporting Evidence: GO_REF:0000024 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0009143 nucleoside triphosphate catabolic process | IBA GO_REF:0000033 | ACCEPT | Summary: ENPP1 directly catalyzes nucleoside-triphosphate breakdown. Reason: The cached PTN002562515 IBD includes direct human descendant support; the human target appearing among sources is legitimate. Human PC-1 expression and NTPPPH measurements in PMID:11159191 Fig. 9 support the activity; purified mouse ENPP1 in PMID:23027977 Fig. 1 generates AMP and PPi from ATP. These are enzyme-performed reaction steps. Supporting Evidence: GO_REF:0000033 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0009143 nucleoside triphosphate catabolic process | IDA PMID:10513816 Differential mechanisms of inorganic pyrophosphate productio... | ACCEPT | Summary: ENPP1 directly catalyzes nucleoside-triphosphate breakdown. Reason: The operative PMID:10513816 original remains unavailable. Independent human PC-1 NTPPPH and PPi assays in PMID:11159191 Fig. 9 and mouse ATP product identification in PMID:23027977 establish the biochemical step. Retain the process while preserving the original citation and its access limitation. Supporting Evidence: file:human/ENPP1/ENPP1-source-guide.md |
| GO:0009143 nucleoside triphosphate catabolic process | IEA GO_REF:0000117 | ACCEPT | Summary: ENPP1 directly catalyzes nucleoside-triphosphate breakdown. Reason: ARBA00091019 was recovered and its relevant FunFam-plus-Primates condition set matches human ENPP1. Human PC-1 expression and NTPPPH measurements in PMID:11159191 Fig. 9 support the activity; purified mouse ENPP1 in PMID:23027977 Fig. 1 generates AMP and PPi from ATP. These are enzyme-performed reaction steps. Supporting Evidence: GO_REF:0000117 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0009986 cell surface | IBA GO_REF:0000033 | ACCEPT | Summary: ENPP1 acts at the cell surface. Reason: The cached PTN002562515 IBD includes cell-surface location with human and mouse evidence. Human PC-1 surface flow cytometry in PMID:8001561 Fig. 4 and human valve-cell localization in PMID:25644539 independently support the assertion. Supporting Evidence: GO_REF:0000033 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0009986 cell surface | IDA PMID:10513816 Differential mechanisms of inorganic pyrophosphate productio... | ACCEPT | Summary: ENPP1 is a cell-surface ectoenzyme. Reason: The original PMID:10513816 localization experiments were not recovered. Independently examined human PC-1 surface flow cytometry in PMID:8001561 p. 439/Fig. 4 and human valve-cell localization in PMID:25644539 support the assertion; these do not verify the unread source experiment. Supporting Evidence: file:human/ENPP1/ENPP1-source-guide.md |
| GO:0010467 gene expression | IDA PMID:28592560 Ectopic calcification in pseudoxanthoma elasticum responds t... | UNDECIDED | Summary: The intended experimental support for ENPP1 participation in gene expression remains unresolved. Reason: PMID:28592560, Results on patient fibroblasts and Fig. 2C–F, compares human ABCC6-, ENPP1- and NT5E-mutant cells. Fig. 2D measures ENPP1 mRNA itself; Fig. 2F finds unchanged NT5E mRNA in ENPP1-mutant cells despite lower CD73 activity. The ALPL expression increase is measured in ABCC6-mutant cells, and Discussion/Fig. 7 proposes an explicitly untested ENPP1-to-AMP-to-adenosine/receptor pathway affecting TNAP expression. The inspected experiments therefore raise a concern about conflating an expression readout or regulatory consequence with involvement in the gene-sequence-to-product process defined by GO:0010467. However, detailed supplementary methods remain unavailable, and the experimental curator may have relied on evidence not inspected here. Retain UNDECIDED and the curator source query rather than remove an IDA assertion from incomplete experimental coverage. This does not deny a role in downstream expression regulation. |
| GO:0016020 membrane | ISS GO_REF:0000024 | MODIFY | Summary: Plasma membrane is the supported specific location for the membrane-anchored ENPP1 product. Reason: The verified mouse P06802 donor has type-II membrane topology and experimentally established basolateral targeting. Human surface expression is independently shown in PMID:8001561 Fig. 4. Replace generic membrane with GO:0005886, already supported by the existing human plasma-membrane rows, rather than retaining redundant location generality. The soluble processed product remains distinguished in product notes. Proposed replacements: plasma membrane Supporting Evidence: GO_REF:0000024 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0016020 membrane | TAS PMID:1315502 Molecular cloning of cDNAs for human fibroblast nucleotide p... | MODIFY | Summary: Plasma membrane is the independently established specific ENPP1 membrane location. Reason: PMID:1315502 was accessible only as an abstract. Human PC-1 surface expression in PMID:8001561 Fig. 4 independently supports replacement of the generic membrane term by GO:0005886, already represented in the specific plasma-membrane rows. This refinement does not claim that the unread cloning original was assessed. The soluble processed chain remains distinguished from the anchored protein. Proposed replacements: plasma membrane |
| GO:0016192 vesicle-mediated transport | IEA GO_REF:0000108 | MARK AS OVER ANNOTATED | Summary: The vesicle-transport inference depends on an unsupported scavenger-receptor assignment. Reason: The imported supporting entity is GO:0005044. Its mapped ligand-delivery function is not established for ENPP1 by the somatomedin-B domain. PMID:11598187 studies ENPP1 sorting as membrane cargo; this does not establish that ENPP1 performs vesicle transport. PMID:26065921 demonstrates ABCG2 association/surface localization but does not resolve a vesicle-transport step performed by ENPP1. This is a scope concern, not a claim that ENPP1 never traffics. Supporting Evidence: GO_REF:0000108 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0016323 basolateral plasma membrane | EXP PMID:11598187 Characterization of a di-leucine-based signal in the cytopla... | KEEP AS NON CORE | Summary: Mouse ENPP1 basolateral targeting is consistent with the conserved human targeting motif. Reason: PMID:11598187 Methods identifies mouse NPP1 constructs expressed in canine MDCK cells. Figs. 2–3 demonstrate basolateral localization by imaging and sided surface biotinylation; Figs. 6 and 9 test the sorting motif, including its human/mouse conservation. Retain this context-dependent location with explicit ortholog scope, without claiming direct human imaging or that wild-type ENPP1 performs endocytosis. |
| GO:0016323 basolateral plasma membrane | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: Basolateral targeting is supported as a cell-context-dependent ENPP1 location. Reason: SL-0026 maps to basolateral cell membrane. PMID:11598187 Methods uses mouse NPP1 in canine MDCK cells; Figs. 2–3 establish localization and Fig. 9 tests a targeting motif conserved in human and mouse. Retain the location with explicit ortholog scope rather than claim direct human imaging. |
| GO:0016323 basolateral plasma membrane | NAS PMID:9553761 Ecto-phosphodiesterase/pyrophosphatase of lymphocytes and no... | KEEP AS NON CORE | Summary: Basolateral targeting is supported by independent ortholog evidence. Reason: PMID:9553761 remained abstract-only, so the cited review’s original human context was not assessed. PMID:11598187 directly tests mouse NPP1 in polarized MDCK cells and a conserved human/mouse targeting motif. Retain the context-dependent basolateral location with this explicit species boundary; do not present the independent paper as verification of the unread review. |
| GO:0016787 hydrolase activity | IEA GO_REF:0000002 | MODIFY | Summary: Specific ATP diphosphatase and cGAMP hydrolase activities describe ENPP1 hydrolysis. Reason: IPR001604/IPR020821 genuinely match ENPP1, but generic hydrolase is less informative than the two established substrate reactions. Human PC-1 NTPPPH/PPi activity in PMID:11159191, product-resolved mouse ATP assays in PMID:23027977 and native-cell/recombinant cGAMP evidence in PMID:25344812 support replacement by GO:0047693 and GO:0106177, which are already present in specific catalytic rows. The two replacements represent distinct reactions and are not an ancestor–descendant pair. Proposed replacements: ATP diphosphatase activity cyclic-GMP-AMP hydrolase activity Supporting Evidence: GO_REF:0000002 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0016791 phosphatase activity | IDA PMID:28592560 Ectopic calcification in pseudoxanthoma elasticum responds t... | MODIFY | Summary: ENPP1 catalyzes nucleotide-triphosphate cleavage that releases PPi, rather than the phosphomonoester hydrolysis defined by GO:0016791. Reason: PMID:28592560 Figure 2C reports ENPP1 enzyme activity and Figure 7 places ENPP1 at ATP conversion to AMP plus PPi, separate from CD73 conversion of AMP and TNAP hydrolysis of PPi. GO:0016791 defines phosphoric-monoester hydrolysis releasing phosphate. The appropriate bond-specific activity is GO:0047429, independently supported by the human PC-1 NTPPPH and PPi experiments in PMID:11159191 Figure 9. This is a lateral chemical correction, not a claim that the replacement is a descendant of phosphatase activity. The inaccessible supplemental assay protocol is not claimed to establish any particular synthetic substrate. Proposed replacements: nucleoside triphosphate diphosphatase activity |
| GO:0030247 polysaccharide binding | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: A real somatomedin-B domain match is insufficiently specific for the polysaccharide ligand class. Reason: The inspected InterPro IPR020436 entry groups somatomedin-B domains in several proteins and maps them to GO:0030247. ENPP1 evidence instead establishes disulfide-dependent oligomerization (PMID:28964717, Fig. 4f–h) and a mobile domain arrangement distinct from ENPP2 (PMID:23027977, SMB-Like Domains). Neither supplies recognition of a polymer of glycosidically linked monosaccharides, the specific ligand class required by this term. The domain-level functional transfer therefore overshoots the target evidence and is marked over-annotated. This is an assessment of the accessible electronic mapping, not an unavailable-publication judgment or proof that all polysaccharide binding is impossible. Unlike scavenger-receptor activity, this term requires no endocytosis; the objection is ligand specificity, not missing transport. Supporting Evidence: GO_REF:0000002 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0030282 bone mineralization | IDA PMID:28652107 Plasma PPi Deficiency Is the Major, but Not the Exclusive, C... | MODIFY | Summary: Human ENPP1 modulates bone mineralization through PPi balance in a mouse transgenic rescue model. Reason: PMID:28652107 expresses human ENPP1 in Enpp1-asj mice, raises plasma PPi, and improves femoral mineral density/microarchitecture. This supports regulation of bone mineralization rather than ENPP1 directly depositing hydroxyapatite. Table 3 shows incomplete and sex-dependent rescue, so neither uniform normalization nor an unconditional positive or negative direction is asserted. The human transgene contributes direct chemical activity, but the phenotypic context is mouse and the accelerating diet must remain explicit. Proposed replacements: regulation of bone mineralization |
| GO:0030308 negative regulation of cell growth | IDA PMID:17849011 Role of ENPP1 on adipocyte maturation. | MODIFY | Summary: The experiment measures reduced cell population expansion rather than reduced individual-cell growth. Reason: PMID:17849011 Figure 2C counts cells during differentiation after stable expression of human ENPP1 K121K or K121Q in mouse 3T3-L1 cells. Viability measurements found no increased cell death. Current GO cell growth concerns increased individual-cell size, which was not measured. Negative regulation of cell population proliferation better matches the endpoint; this is a context-dependent overexpression phenotype. Proposed replacements: negative regulation of cell population proliferation |
| GO:0030318 melanocyte differentiation | IMP PMID:28964717 ENPP1 Mutation Causes Recessive Cole Disease by Altering Mel... | UNDECIDED | Summary: Patient ENPP1 mutations alter melanocyte pigmentation and gene-expression state; whether this establishes melanocyte differentiation remains unresolved. Reason: PMID:28964717 Figs. 3 and 5 examine skin pigmentation and already isolated patient melanocytes. Development/pigmentation pathways derive from RNA-seq enrichment, with selected transcripts checked by qPCR. GO:0030318 requires acquisition of specialized melanocyte features by an initially unspecialized cell. These data do not resolve that transition or the relevant ENPP1 process role; retain uncertainty without rejecting the human phenotype. |
| GO:0030500 regulation of bone mineralization | IBA GO_REF:0000033 | ACCEPT | Summary: ENPP1-derived PPi regulates bone mineralization. Reason: The cached PTN002562515 IBD has mouse and zebrafish descendant evidence. Independent human-PC-1 cell assays in PMID:11159191 establish extracellular PPi generation, and human ENPP1 expression in mutant mice in PMID:28652107 Fig. 3/Table 3 changes bone mineralization parameters. ENPP1 supplies a biochemical regulator, rather than directly depositing mineral. The regulation can differ by tissue and phosphate/PPi balance. Supporting Evidence: GO_REF:0000033 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0030500 regulation of bone mineralization | IC PMID:10513816 Differential mechanisms of inorganic pyrophosphate productio... | ACCEPT | Summary: ENPP1-derived extracellular PPi regulates mineralization. Reason: The IC source retains GO:0030505 and PMID:10513816, whose operative original was inaccessible. Independent human PC-1 NTPPPH/PPi production in PMID:11159191 and human ENPP1 transgene effects on mouse bone in PMID:28652107 support mineralization regulation. This independently supports the biological assertion while leaving the original transport-based inference unverified; it does not endorse ENPP1-mediated PPi transport. Supporting Evidence: file:human/ENPP1/ENPP1-source-guide.md |
| GO:0030502 negative regulation of bone mineralization | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: ENPP1 can restrain mineral deposition by generating extracellular PPi. Reason: The verified mouse donor carries experimentally supported negative regulation annotations. Independent human-PC-1 PPi production in PMID:11159191 and human ENPP1 transgene experiments in PMID:28652107 support the conserved anti-calcification chemistry. Retain the signed bone-mineralization role as context-dependent: PPi deficiency and altered Pi balance can produce distinct skeletal outcomes, and this is not a universal direction for every bone measurement. Supporting Evidence: GO_REF:0000024 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0030505 inorganic diphosphate transport | IBA GO_REF:0000033 | MARK AS OVER ANNOTATED | Summary: The inherited PPi-transport label exceeds the demonstrated role of ENPP1 in extracellular PPi generation. Reason: The actual PTN002562515 IBD has human and mouse descendant support; the concern is process meaning, not donor count, target self-support or an inferred node-placement error. Current GO:0030505 requires directed movement by an agent such as a transporter or pore. Human PMID:11159191 Fig. 9 measures enzymatic PPi production. Mouse donor PMID:28701330 Figs. 1/3 tests supplied-PPi uptake and rescue, and PMID:28704395 Figs. 1–4 tests PPi levels and rescue in Npt2a/Enpp1 mutants. These originals distinguish ENPP1 production from transport and do not establish ENPP1 executing the movement. The unread human PMID:10513816 experimental row remains separately unresolved. Supporting Evidence: GO_REF:0000033 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0030505 inorganic diphosphate transport | IDA PMID:10513816 Differential mechanisms of inorganic pyrophosphate productio... | UNDECIDED | Summary: PMID:10513816 provides an abstract-level lead, but the original experimental evidence remains inaccessible. Reason: The abstract reports altered extracellular PPi, which by itself cannot distinguish extracellular production from directed transmembrane transport. Publisher access attempts did not recover the original Methods, Results, or captions. Retain source-specific uncertainty; this is not a finding that the annotation is false. For GO:0030505 specifically, production/release of a measured metabolite is not itself a demonstration of transport by ENPP1. No construct species, transport mechanism, or misattribution is inferred from the abstract. |
| GO:0030643 intracellular phosphate ion homeostasis | IDA PMID:11159191 PC-1 nucleoside triphosphate pyrophosphohydrolase deficiency... | MARK AS OVER ANNOTATED | Summary: The original intracellular assay measures PPi, not the phosphate ions specified by this term. Reason: PMID:11159191 Methods and Figure 3 address intracellular and extracellular inorganic pyrophosphate (PPi), which were both low in proband fibroblasts. Human PC-1 transfection increases NTPPPH activity and extracellular PPi. These are positive observations of PPi production and abundance, but they do not demonstrate maintenance of intracellular orthophosphate (Pi) concentrations. The Discussion contrasts the PC-1 pattern with the ANK phenotype and explicitly says ANK was not investigated. The source therefore overextends to Pi-specific homeostasis; possible phosphate-related roles supported elsewhere are not excluded. |
| GO:0032869 cellular response to insulin stimulus | IDA PMID:17849011 Role of ENPP1 on adipocyte maturation. | KEEP AS NON CORE | Summary: Human ENPP1 overexpression modifies the insulin response of mouse adipocyte cells. Reason: PMID:17849011 Methods and Figure 4 show reduced insulin-induced receptor/Akt phosphorylation and glucose uptake in 3T3-L1 cells expressing human ENPP1 K121K or K121Q. Retain this broad insulin-response annotation as a non-core contextual role; the experiment is not a direct ENPP1–insulin-binding assay. |
| GO:0032869 cellular response to insulin stimulus | IDA PMID:7830796 Membrane glycoprotein PC-1 and insulin resistance in non-ins... | KEEP AS NON CORE | Summary: ENPP1 can modulate cellular insulin responses. Reason: PMID:7830796 remains abstract-only. Independently assessed PMID:17849011 Fig. 4 shows reduced insulin-induced receptor/Akt phosphorylation and glucose uptake in mouse cells expressing human ENPP1, and PMID:11289049 measures receptor association and insulin-dependent glycogen responses in human cells. Retain this contextual role as non-core while leaving the original 1995 assay details unverified. Supporting Evidence: file:human/ENPP1/ENPP1-source-guide.md |
| GO:0033198 response to ATP | IDA PMID:25644539 Adenosine derived from ecto-nucleotidases in calcific aortic... | MODIFY | Summary: ENPP1 contributes an enzymatic step in the cellular response to extracellular ATP in human VICs. Reason: PMID:25644539 finds that NPP1 knockdown reduces ATP-induced mineralization in human VIC cultures, alongside loss of NPP1 expression/activity. ENPP1 performs ATP-to-AMP conversion; CD73 then generates adenosine and A2a receptor signaling mediates the response. GO:0071318 specifies the cellular scale actually tested and is a verified descendant of response to ATP. This does not assign ATP receptor activity or direct adenosine production to ENPP1, and it does not imply that all tissues respond with increased mineralization. Proposed replacements: cellular response to ATP |
| GO:0036219 GTP diphosphatase activity | IEA GO_REF:0000116 | KEEP AS NON CORE | Summary: GTP diphosphatase activity is supported within ENPP1 substrate breadth. Reason: RHEA:29391 directly matches GTP-to-GMP-plus-PPi chemistry. PMID:23027977 Substrate Specificity/Fig. 1 measures purified mouse enzyme kinetics and resolves a GMP-bound structure. Retain the conserved alternative-substrate activity as non-core; the mouse kinetics do not establish a physiological human GTP flux or human numerical constants. |
| GO:0036219 GTP diphosphatase activity | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: GTP diphosphatase activity is supported within ENPP1 substrate breadth. Reason: P06802 is the verified mouse Enpp1 ortholog, with a direct PMID:23027977 GTP activity record. PMID:23027977 Substrate Specificity/Fig. 1 measures purified mouse enzyme kinetics and resolves a GMP-bound structure. Retain the conserved alternative-substrate activity as non-core; the mouse kinetics do not establish a physiological human GTP flux or human numerical constants. |
| GO:0036221 UTP diphosphatase activity | EXP PMID:28011303 The promiscuous ectonucleotidase NPP1: molecular insights in... | UNDECIDED | Summary: The cited human UTP assay remains inaccessible; independent mouse evidence supports a conserved activity. Reason: PMID:28011303 has a bibliography-only normal cache. The separately retrieved ScienceDirect abstract and section previews at https://doi.org/10.1016/j.bbagen.2016.12.019 describe biochemical experiments combined with homology modeling and docking; complete Methods, the protein preparation and Table 1 were not recovered. The indexed abstract names UTP. Independent PMID:23027977 Substrate Specificity/Fig. 1 measures purified mouse ENPP1 UTP turnover, supporting conserved substrate use, but it does not verify the unread human preparation in this citation. Retain the source-specific UNDECIDED judgment. |
| GO:0036221 UTP diphosphatase activity | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: UTP diphosphatase activity is supported as part of ENPP1 substrate breadth. Reason: The official RHEA:29395 equation matches UTP-to-UMP-plus-PPi hydrolysis. The current ARBA00098322 endpoint was unavailable, so no rule conditions are invented. PMID:23027977 directly measures the mouse ortholog using UTP; this supports retaining the conserved alternative-substrate activity as non-core, without claiming the inaccessible human PMID:28011303 methods were assessed. Supporting Evidence: GO_REF:0000120 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0042803 protein homodimerization activity | IDA PMID:28964717 ENPP1 Mutation Causes Recessive Cole Disease by Altering Mel... | KEEP AS NON CORE | Summary: Wild-type human ENPP1 forms disulfide-linked homodimers in the tested expression system. Reason: PMID:28964717 Fig. 4f-h compares wild-type, C120R and C164S in HEK293T cells under reducing and nonreducing conditions. Retain the measured oligomerization as non-core; the experiment does not establish obligatory dimerization of every processed ENPP1 product. |
| GO:0042803 protein homodimerization activity | IDA PMID:7830796 Membrane glycoprotein PC-1 and insulin resistance in non-ins... | KEEP AS NON CORE | Summary: Human ENPP1 homodimerization is independently established. Reason: The operative PMID:7830796 original was unavailable. PMID:8001561 pp. 437–438/Fig. 3 and PMID:28964717 Fig. 4f–h independently show human ENPP1 monomer/dimer behavior under reducing and nonreducing conditions. Retain oligomerization as non-core, without asserting that every processed product is dimeric or that the unread 1995 experiment was assessed. |
| GO:0045599 negative regulation of fat cell differentiation | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: ENPP1 can negatively regulate adipocyte differentiation in the tested expression context. Reason: The cached PTN002562515 IBD records human and mouse descendant evidence. PMID:17849011 Figs. 2–3 uses human ENPP1 in mouse 3T3-L1 cells and Fig. 5 supplies separate mouse-knockout support. Retain the context-dependent regulatory phenotype, without requiring ENPP1 itself to catalyze an adipogenesis reaction or claiming a universal effect. |
| GO:0045599 negative regulation of fat cell differentiation | IDA PMID:17849011 Role of ENPP1 on adipocyte maturation. | KEEP AS NON CORE | Summary: Human ENPP1 overexpression suppresses adipocyte maturation in the tested culture system. Reason: PMID:17849011 Figures 2–3 show reduced lipid accumulation and adipogenic markers in mouse 3T3-L1 cells expressing human ENPP1 K121K or K121Q. Figure 5 supplies separate corroboration from mouse Enpp1-knockout embryonic fibroblasts. Retain the differentiation effect as non-core and distinguish the human transgene from the mouse loss-of-function experiment. |
| GO:0045719 negative regulation of glycogen biosynthetic process | IDA PMID:11289049 The Q allele variant (GLN121) of membrane glycoprotein PC-1 ... | KEEP AS NON CORE | Summary: Human ENPP1 reduces insulin-stimulated glycogen synthesis in MCF-7 cells. Reason: PMID:11289049 Methods, Results, and Figure 6 measure reduced radiolabeled glucose incorporation into glycogen with human K121/Q121 ENPP1. Retain this downstream effect as non-core. |
| GO:0046034 ATP metabolic process | IBA GO_REF:0000033 | ACCEPT | Summary: ENPP1 directly consumes extracellular ATP to form AMP and PPi. Reason: The cached PTN002562515 IBD carries the ATP-metabolism assertion with human and mouse evidence. Human valve-cell experiments in PMID:25644539 and purified mouse enzyme assays in PMID:23027977 establish an enzyme-performed ATP metabolic step. Retain the broader process alongside existing catabolic and catalytic terms. Supporting Evidence: GO_REF:0000033 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0046034 ATP metabolic process | IDA PMID:25644539 Adenosine derived from ecto-nucleotidases in calcific aortic... | ACCEPT | Summary: ENPP1 executes ATP metabolism by converting ATP to AMP and PPi. Reason: PMID:25644539 distinguishes the upstream NPP1 reaction from downstream CD73 production of adenosine. Human VIC NPP1 knockdown reduces enzyme activity and ATP-dependent mineralization, consistent with ENPP1 catalyzing the ATP-metabolism step. ATP is the substrate, while ENPP1 performs the chemical work; the evidence does not assign adenosine generation to ENPP1 itself. |
| GO:0046034 ATP metabolic process | ISS GO_REF:0000024 | ACCEPT | Summary: ENPP1 directly consumes extracellular ATP to form AMP and PPi. Reason: The verified mouse P06802 donor has direct ATP-hydrolysis evidence in PMID:23027977. Human valve-cell experiments in PMID:25644539 and purified mouse enzyme assays in PMID:23027977 establish an enzyme-performed ATP metabolic step. Retain the broader process alongside existing catabolic and catalytic terms. Supporting Evidence: GO_REF:0000024 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0046325 negative regulation of D-glucose import across plasma membrane | IDA PMID:17849011 Role of ENPP1 on adipocyte maturation. | KEEP AS NON CORE | Summary: Human ENPP1 overexpression decreases insulin-stimulated glucose uptake in the tested adipocyte model. Reason: PMID:17849011 glucose-transport Methods and Figure 4 measure radiolabeled 2-deoxyglucose uptake in mouse 3T3-L1 cells expressing human ENPP1 K121K or K121Q. The reduced insulin-dependent uptake supports a non-core regulatory effect; it does not show direct ENPP1 binding to or catalysis by a glucose transporter. |
| GO:0046627 negative regulation of insulin receptor signaling pathway | IDA PMID:17849011 Role of ENPP1 on adipocyte maturation. | KEEP AS NON CORE | Summary: Human ENPP1 suppresses insulin-receptor signaling in the tested expression system. Reason: PMID:17849011 Figure 4 measures reduced insulin-stimulated receptor phosphorylation and downstream Akt phosphorylation in mouse 3T3-L1 cells expressing human ENPP1 K121K or K121Q. Retain the experimentally supported signaling effect as non-core. This source does not independently test the proposed physical receptor-binding mechanism. |
| GO:0046627 negative regulation of insulin receptor signaling pathway | IDA PMID:7830796 Membrane glycoprotein PC-1 and insulin resistance in non-ins... | KEEP AS NON CORE | Summary: ENPP1 can suppress insulin-receptor signaling in the tested cell systems. Reason: PMID:7830796 remains abstract-only. Independent human ENPP1 expression experiments in PMID:17849011 Fig. 4 reduce receptor and Akt phosphorylation, and PMID:11289049 independently supports receptor association and reduced insulin responses. Retain the contextual signaling regulation as non-core, without claiming the unread 1995 assay or a purified receptor-inhibition mechanism was verified. Supporting Evidence: file:human/ENPP1/ENPP1-source-guide.md |
| GO:0046872 metal ion binding | IEA GO_REF:0000002 | MODIFY | Summary: Zinc and calcium binding specify the established ENPP1 metal sites. Reason: The InterPro domain matches are supported by the resolved mouse ENPP1 sites in PMID:23027977 Catalytic Domain/Nuclease-Like Domain sections. Replace generic metal binding with GO:0008270 zinc binding and GO:0005509 calcium binding, already represented by the specific ortholog-supported rows. The two zinc ions are catalytic and the separate calcium site is structural; mouse residue coordinates are not copied onto human ENPP1. Proposed replacements: zinc ion binding calcium ion binding |
| GO:0047429 nucleoside triphosphate diphosphatase activity | EXP PMID:28011303 The promiscuous ectonucleotidase NPP1: molecular insights in... | ACCEPT | Summary: Nucleoside-triphosphate diphosphatase is independently established ENPP1 activity. Reason: Retain the independently established ENPP1 activity on the additional directly read originals, with the species and construct boundaries in the source guide. PMID:28011303 has a bibliography-only normal cache. The separately retrieved ScienceDirect abstract and section previews at https://doi.org/10.1016/j.bbagen.2016.12.019 describe biochemical experiments combined with homology modeling and docking; complete Methods, the protein preparation and Table 1 were not recovered. The indexed material is corroboration, not independent verification of the 2017 experiment. PMID:23027977 Substrate Specificity/Fig. 1 supplies direct multi-nucleotide enzymology; PMID:25344812 provides additional ATP and cGAMP evidence. Supporting Evidence: file:human/ENPP1/ENPP1-source-guide.md |
| GO:0047429 nucleoside triphosphate diphosphatase activity | IDA PMID:10513816 Differential mechanisms of inorganic pyrophosphate productio... | ACCEPT | Summary: Nucleoside-triphosphate diphosphatase is independently established ENPP1 activity. Reason: The operative PMID:10513816 original was inaccessible. Human PC-1 expression and NTPPPH/PPi measurements in PMID:11159191 and mouse product-resolved ATP hydrolysis in PMID:23027977 support the general catalytic function. Retain the annotation while preserving the cited experiment’s access limitation; no exact substrate conditions are attributed to the unread paper. Supporting Evidence: file:human/ENPP1/ENPP1-source-guide.md |
| GO:0047429 nucleoside triphosphate diphosphatase activity | IDA PMID:11159191 PC-1 nucleoside triphosphate pyrophosphohydrolase deficiency... | ACCEPT | Summary: Human PC-1 expression increases NTPPPH activity and extracellular PPi. Reason: PMID:11159191 transfects human PC-1 into human aortic smooth muscle cells and demonstrates increased NTPPPH activity and extracellular PPi in Figure 9. PC-1-deficient proband fibroblasts likewise show low NTPPPH/PPi and respond to wild-type PC-1 expression, with that rescue described without displayed data. These experiments support the ENPP1 nucleoside triphosphate diphosphatase activity; no exact synthetic assay substrate or natural protein isoform is inferred. |
| GO:0047429 nucleoside triphosphate diphosphatase activity | IDA PMID:25344812 Hydrolysis of 2'3'-cGAMP by ENPP1 and design of nonhydrolyza... | ACCEPT | Summary: ENPP1 catalyzes nucleoside-triphosphate diphosphatase reactions. Reason: ENPP1 nucleoside-triphosphate diphosphatase activity is established. PMID:25344812 Fig.2 includes ATP hydrolysis by the commercial ENPP1 preparation; independent mouse extracellular-enzyme work in PMID:23027977 establishes ATP conversion to AMP and PPi. The cited commercial preparation must not be represented as the full natural human protein, and neither experiment establishes equal physiological relevance for every nucleotide substrate. |
| GO:0047429 nucleoside triphosphate diphosphatase activity | IDA PMID:7830796 Membrane glycoprotein PC-1 and insulin resistance in non-ins... | ACCEPT | Summary: Nucleoside-triphosphate diphosphatase is independently established ENPP1 activity. Reason: The operative PMID:7830796 original was inaccessible. Human PC-1 expression and NTPPPH/PPi measurements in PMID:11159191 and mouse product-resolved ATP hydrolysis in PMID:23027977 support the general catalytic function. Retain the annotation while preserving the cited experiment’s access limitation; no exact substrate conditions are attributed to the unread paper. Supporting Evidence: file:human/ENPP1/ENPP1-source-guide.md |
| GO:0047429 nucleoside triphosphate diphosphatase activity | IEA GO_REF:0000120 | ACCEPT | Summary: ENPP1 catalyzes nucleoside-triphosphate cleavage yielding monophosphate and PPi. Reason: Official RHEA:23996 is the general NTP reaction; RHEA:27762 is its CTP example, consistent with EC:3.6.1.9. Human PC-1 assays in PMID:11159191 and purified mouse enzyme in PMID:23027977 independently establish this chemistry. Retain the general catalytic function without treating alternate substrate turnover as equal physiological importance. Supporting Evidence: GO_REF:0000120 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0047693 ATP diphosphatase activity | EXP PMID:25344812 Hydrolysis of 2'3'-cGAMP by ENPP1 and design of nonhydrolyza... | ACCEPT | Summary: ATP-to-AMP/PPi hydrolysis is a central ENPP1 reaction. Reason: ATP diphosphatase is a central ENPP1 activity. PMID:25344812 Fig.2 measures ATP hydrolysis with a commercial reagent; PMID:23027977 directly resolves AMP and PPi products in mouse extracellular ENPP1 assays. Retain the existing source context while distinguishing preparation-specific kinetics from full-length human protein measurements. |
| GO:0047693 ATP diphosphatase activity | EXP PMID:28011303 The promiscuous ectonucleotidase NPP1: molecular insights in... | ACCEPT | Summary: ATP diphosphatase activity is independently established. Reason: Retain the independently established ENPP1 activity on the additional directly read originals, with the species and construct boundaries in the source guide. PMID:28011303 has a bibliography-only normal cache. The separately retrieved ScienceDirect abstract and section previews at https://doi.org/10.1016/j.bbagen.2016.12.019 describe biochemical experiments combined with homology modeling and docking; complete Methods, the protein preparation and Table 1 were not recovered. The indexed material is corroboration, not independent verification of the 2017 experiment. PMID:23027977 Substrate Specificity/Fig. 1 and PMID:25344812 Fig. 2 supply independent ATP-hydrolysis evidence. Supporting Evidence: file:human/ENPP1/ENPP1-source-guide.md |
| GO:0047693 ATP diphosphatase activity | IEA GO_REF:0000120 | ACCEPT | Summary: ENPP1 hydrolyzes ATP to AMP and PPi. Reason: RHEA:14245 explicitly records this reaction. ARBA00098486 was unavailable at its current endpoint, so its rule conditions were not reconstructed. Human PC-1 NTPPPH/PPi assays in PMID:11159191, human valve-cell ATP metabolism in PMID:25644539, and mouse product identification in PMID:23027977 independently support the core reaction. Supporting Evidence: GO_REF:0000120 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0048513 animal organ development | IEA GO_REF:0000117 | UNDECIDED | Summary: The specific developmental scope of the rule-derived organ-development assertion remains unresolved. Reason: ARBA00029247 was recovered and a matching three-FunFam condition set was verified. The assessed human-transgene evidence establishes extracellular PPi control and partial bone-mineralization rescue. It does not resolve whether the relevant ENPP1 contribution is to organ formation/progression or to mineral balance in an existing organ. A regulatory contribution can legitimately participate in development; neither the breadth of the term nor lack of a developmental-machinery role is grounds to reject it. Retain uncertainty while preserving the established mineralization regulation. Supporting Evidence: GO_REF:0000117 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0050427 3'-phosphoadenosine 5'-phosphosulfate metabolic process | IDA PMID:7830796 Membrane glycoprotein PC-1 and insulin resistance in non-ins... | UNDECIDED | Summary: PAPS metabolism could not be verified in the cited original. Reason: The available PMID:7830796 abstract and landing page do not expose a PAPS substrate or product experiment, and the full Methods and Results were unavailable. This access limit cannot establish absence of the assay or miscitation. Leave the process assertion unresolved pending operative original evidence. |
| GO:0050656 3'-phosphoadenosine 5'-phosphosulfate binding | IC PMID:7830796 Membrane glycoprotein PC-1 and insulin resistance in non-ins... | UNDECIDED | Summary: The inferred PAPS-binding assertion remains unresolved with its supporting metabolism claim. Reason: This IC row explicitly depends on GO:0050427. Operative PAPS-metabolism evidence in PMID:7830796 was unavailable, so that inference cannot be independently assessed. The uncertainty does not imply that ENPP1 cannot bind PAPS, and the existing supporting entity is preserved. |
| GO:0055062 phosphate ion homeostasis | IDA PMID:28652107 Plasma PPi Deficiency Is the Major, but Not the Exclusive, C... | MARK AS OVER ANNOTATED | Summary: The transgenic study establishes PPi correction without demonstrating Pi-specific homeostasis. Reason: PMID:28652107 Table 2 shows major changes and rescue in plasma PPi and the PPi/Pi ratio following human ENPP1 expression in mouse disease models, while plasma Pi and Ca/Pi are not significantly altered. Thus the experiment supports regulation of extracellular PPi availability and mineralization, but does not itself demonstrate maintenance of phosphate-ion concentration as defined by GO:0055062. This is a source-specific overextension, not a claim that ENPP1 cannot affect phosphate physiology in another setting. |
| GO:0090304 nucleic acid metabolic process | IDA PMID:22285541 Characterization of human phosphodiesterase 12 and identific... | UNDECIDED | Summary: ENPP1 oligoadenylate-metabolism evidence remains incompletely assessed. Reason: PMID:22285541 explicitly reports ENPP1 oligoadenylate nuclease activity, but the accessible abstract does not resolve the ENPP1-specific assay and physiological compartment. The experimental context underlying this broad nucleic-acid-metabolism annotation remains unverified; do not infer it is erroneous merely because PDE12 is foregrounded. |
| GO:0106177 cyclic-GMP-AMP hydrolase activity | EXP PMID:28011303 The promiscuous ectonucleotidase NPP1: molecular insights in... | ACCEPT | Summary: ENPP1 cGAMP hydrolase activity is independently established. Reason: Retain the independently established ENPP1 activity on the additional directly read originals, with the species and construct boundaries in the source guide. PMID:28011303 has a bibliography-only normal cache. The separately retrieved ScienceDirect abstract and section previews at https://doi.org/10.1016/j.bbagen.2016.12.019 describe biochemical experiments combined with homology modeling and docking; complete Methods, the protein preparation and Table 1 were not recovered. The indexed material is corroboration, not independent verification of the 2017 experiment. PMID:25344812 Figs. 1–3 and PMID:30356045 Figs. 1–3 independently support cGAMP hydrolysis. Supporting Evidence: file:human/ENPP1/ENPP1-source-guide.md |
| GO:0106177 cyclic-GMP-AMP hydrolase activity | IBA GO_REF:0000033 | ACCEPT | Summary: ENPP1 hydrolyzes extracellular cGAMP. Reason: The cached PTN002562515 IBD explicitly carries cGAMP hydrolase activity with human and mouse support. PMID:25344812 combines recombinant assays with native human-cell knockdown and mouse knockout evidence; PMID:30356045 adds mouse structural mechanism and separately identified human reporter constructs. The source guide distinguishes engineered proteins, natural products and the current commercial datasheet from the historical assay lot. Supporting Evidence: GO_REF:0000033 file:human/ENPP1/ENPP1-source-guide.md |
| GO:0106177 cyclic-GMP-AMP hydrolase activity | IDA PMID:25344812 Hydrolysis of 2'3'-cGAMP by ENPP1 and design of nonhydrolyza... | ACCEPT | Summary: Native-cell, knockout and recombinant experiments support ENPP1 cGAMP hydrolysis. Reason: PMID:25344812 Figs.1–3 combines recombinant 2′3′-cGAMP hydrolysis, human MDA-MB-231 knockdown and mouse knockout tissue/plasma assays. These independent observations support ENPP1 cGAMP hydrolase activity despite the commercial construct boundary. PMID:30356045 adds mouse structural and biochemical support. The findings do not establish cytosolic ENPP1 activity or a transport mechanism. |
| GO:0106177 cyclic-GMP-AMP hydrolase activity | IEA GO_REF:0000116 | ACCEPT | Summary: ENPP1 hydrolyzes extracellular cGAMP. Reason: Official RHEA:58808 gives 2-prime,3-prime-cGAMP hydrolysis to GMP and AMP. PMID:25344812 combines recombinant assays with native human-cell knockdown and mouse knockout evidence; PMID:30356045 adds mouse structural mechanism and separately identified human reporter constructs. The source guide distinguishes engineered proteins, natural products and the current commercial datasheet from the historical assay lot. Supporting Evidence: GO_REF:0000116 file:human/ENPP1/ENPP1-source-guide.md |
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Download this section (compressed HTML)Q: Which ENPP1 constructs and natural oligonucleotide substrates in PMID:22285541 and the older phosphodiesterase-I studies establish cleavage directionality and product identity, distinct from synthetic-substrate hydrolysis?
Q: What experiments support direct ENPP1-dependent PPi movement, as distinct from extracellular PPi generation or uptake of supplied PPi, in the GO:0030505 source chain?
Q: Does the Cole-disease melanocyte phenotype reflect altered differentiation, mature-cell pigmentation, or both, and which ENPP1 biochemical or interaction function mediates it?
Q: Which ENPP1 enrichment and validation data in the PMID:17897319 supplementary tables support lysosomal-membrane localization?
Q: What are the abundance, cleavage site and oligomeric state of the natural soluble human ENPP1 product, and how do its substrate activities compare with membrane-anchored ENPP1?
Q: Can the historical reagent composition used in PMID:25344812 and the human constructs used in PMID:28011303 be documented well enough to assign substrate kinetics to defined ENPP1 products?
Q: Which existing GO process best represents ENPP1-derived pyrophosphate restraining ectopic soft-tissue calcification, separately from its context-dependent effects on bone mineralization?
Q: Does natural ENPP1 encounter and cleave physiological oligonucleotide substrates at relevant extracellular concentrations, and which products and signaling consequences result?
Q: For the PMID:28592560 GO:0010467 assertion, is an experiment beyond Fig. 2C–F and the Discussion/Fig. 7 regulatory model intended to demonstrate ENPP1 participation in producing a gene product, rather than measuring ENPP1 expression or downstream regulation?
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