{"gene":"NAGK","run_date":"2026-06-10T05:19:52","timeline":{"discoveries":[{"year":2022,"finding":"NAGK (N-acetylglucosamine kinase) directly phosphorylates the N-acetylmuramic acid moiety of muramyl dipeptide (MDP) at the hydroxyl group of its C6 position, yielding 6-O-phospho-MDP, which is the actual agonist for NOD2. Unmodified MDP does not activate NOD2; NAGK-phosphorylated MDP is required. Macrophages from NAGK-deficient mice are completely deficient in MDP sensing.","method":"Forward genetic screen, in vitro phosphorylation assay, NAGK knockout mice (macrophage functional assays), chemical characterization of phospho-MDP product","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct enzymatic activity demonstrated in vitro, genetic KO with defined cellular phenotype, product chemically characterized, replicated with mouse model","pmids":["36002575"],"is_preprint":false},{"year":2021,"finding":"NAGK mediates a hexosamine salvage pathway by phosphorylating free GlcNAc to feed UDP-GlcNAc pools when de novo hexosamine synthesis is suppressed by glutamine limitation. NAGK deletion from pancreatic ductal adenocarcinoma (PDA) cells impairs tumor growth in mice.","method":"Isotope tracing/metabolomics, NAGK genetic deletion (CRISPR/KO), xenograft mouse tumor growth assay","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Moderate — metabolic flux tracing with genetic KO and in vivo tumor growth readout, single lab but multiple orthogonal methods","pmids":["34844667"],"is_preprint":false},{"year":2019,"finding":"Nagk and the UDP-GlcNAc glycosylation salvage pathway specifically regulate Wnt signaling during vertebrate development, without affecting Fgf, TGFβ, Notch, or Shh pathways. This role is evolutionarily conserved in Xenopus, zebrafish, and Drosophila. GlcNAc is essential for growth of intestinal enteroids, which are Wnt-dependent.","method":"Kinase screen in Xenopus embryogenesis, pathway-specific reporter assays, genetic loss-of-function in zebrafish and Drosophila, intestinal enteroid growth assay","journal":"Mechanisms of development","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — epistasis and pathway specificity demonstrated across multiple model organisms, single lab, phenotypic readouts without full molecular mechanism","pmids":["30904594"],"is_preprint":false},{"year":2024,"finding":"NAGK knockdown in hypothalamic GT1-7 cells decreases transcription of Gnrh, Kiss1, Gpr54, Igf1, and Mapk14 mRNA and reduces GnRH secretion, while increasing β-catenin mRNA and apoptosis. In vivo, intracerebroventricular Nagk knockdown delays vaginal opening and reduces hypothalamic Gnrh and Kiss1 mRNA levels and serum E2 in female mice, establishing a role for NAGK in regulating puberty onset.","method":"siRNA knockdown in GT1-7 cells, RT-qPCR, GnRH secretion assay, ICV injection knockdown in mice, immunofluorescence, serum hormone measurement","journal":"Theriogenology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — genetic loss-of-function with defined cellular and in vivo phenotypic readouts, single lab, limited mechanistic pathway resolution","pmids":["39488153"],"is_preprint":false}],"current_model":"Human/mammalian NAGK (N-acetylglucosamine kinase) functions as a metabolic kinase with at least two distinct mechanistic roles: (1) it directly phosphorylates the C6-OH of the N-acetylmuramic acid moiety of muramyl dipeptide (MDP), generating 6-O-phospho-MDP, which is the obligate NOD2 agonist required for innate immune sensing of bacterial peptidoglycan; and (2) it phosphorylates free GlcNAc in the hexosamine salvage pathway to replenish UDP-GlcNAc pools under nutrient-limited conditions, supporting glycosylation and cell growth; additionally, NAGK activity in the salvage pathway specifically supports Wnt signaling during development and regulates hypothalamic GnRH/Kiss1 expression and puberty onset."},"narrative":{"mechanistic_narrative":"NAGK (N-acetylglucosamine kinase) is a metabolic sugar kinase with dual roles in innate immunity and hexosamine salvage metabolism [PMID:36002575, PMID:34844667]. In immune sensing, NAGK directly phosphorylates the C6 hydroxyl of the N-acetylmuramic acid moiety of muramyl dipeptide (MDP), generating 6-O-phospho-MDP; this phosphorylated species, not unmodified MDP, is the agonist that activates NOD2, and NAGK-deficient macrophages are completely unable to sense MDP [PMID:36002575]. In parallel, NAGK phosphorylates free GlcNAc to feed UDP-GlcNAc pools through a hexosamine salvage pathway that becomes critical when de novo synthesis is limited by glutamine restriction, a dependence exploited by pancreatic ductal adenocarcinoma cells for tumor growth [PMID:34844667]. This salvage-derived UDP-GlcNAc supply specifically supports Wnt signaling during vertebrate development, conserved across Xenopus, zebrafish, and Drosophila and required for Wnt-dependent intestinal enteroid growth [PMID:30904594]. In the hypothalamus, NAGK supports transcription of Gnrh and Kiss1 and GnRH secretion, and its knockdown delays puberty onset in female mice [PMID:39488153].","teleology":[{"year":2019,"claim":"Establishing whether NAGK has a developmental signaling role beyond housekeeping metabolism, this work showed that NAGK-dependent UDP-GlcNAc salvage selectively gates Wnt signaling.","evidence":"Kinase screen in Xenopus embryogenesis with pathway-specific reporters, genetic loss-of-function in zebrafish and Drosophila, and Wnt-dependent intestinal enteroid growth assay","pmids":["30904594"],"confidence":"Medium","gaps":["Molecular link between UDP-GlcNAc levels and Wnt pathway specificity not resolved","Direct glycosylation target mediating Wnt dependence not identified"]},{"year":2021,"claim":"Defining the metabolic context where NAGK matters, this study showed that NAGK enables a hexosamine salvage route feeding UDP-GlcNAc when de novo synthesis is suppressed, supporting tumor growth.","evidence":"Isotope tracing/metabolomics with CRISPR/KO of NAGK and xenograft tumor growth in mice","pmids":["34844667"],"confidence":"High","gaps":["Downstream glycoproteins dependent on salvage flux not enumerated","Generalizability beyond pancreatic ductal adenocarcinoma not established"]},{"year":2022,"claim":"Resolving the long-standing question of how cytosolic peptidoglycan fragments are recognized, this work identified NAGK as the kinase that converts MDP into the true NOD2 agonist.","evidence":"Forward genetic screen, in vitro phosphorylation assay, chemical characterization of 6-O-phospho-MDP, and NAGK knockout mouse macrophage functional assays","pmids":["36002575"],"confidence":"High","gaps":["Structural basis of MDP recognition by NAGK not defined","How 6-O-phospho-MDP engages NOD2 mechanistically not detailed"]},{"year":2024,"claim":"Extending NAGK into neuroendocrine control, this study linked NAGK activity to hypothalamic GnRH/Kiss1 programs and puberty timing.","evidence":"siRNA knockdown in GT1-7 cells with RT-qPCR and GnRH secretion assays, plus ICV knockdown in mice with hormone measurement and immunofluorescence","pmids":["39488153"],"confidence":"Medium","gaps":["Causal pathway from NAGK kinase activity to Gnrh/Kiss1 transcription not mapped","Relationship between observed β-catenin/Wnt changes and the GnRH phenotype unresolved"]},{"year":null,"claim":"Whether NAGK's metabolic salvage activity and its peptidoglycan-sensing activity are mechanistically coupled, and how a single sugar kinase coordinates these distinct outputs, remains open.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified structural/regulatory model linking the GlcNAc-salvage and MDP-phosphorylation activities","Tissue-specific control of which NAGK function dominates is uncharacterized"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,1]}],"localization":[],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[1]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[0]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[2]}],"complexes":[],"partners":["NOD2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9UJ70","full_name":"N-acetyl-D-glucosamine kinase","aliases":["GlcNAc kinase","Muramyl dipeptide kinase","N-acetyl-D-mannosamine kinase"],"length_aa":344,"mass_kda":37.4,"function":"Converts endogenous N-acetylglucosamine (GlcNAc), a major component of complex carbohydrates, from lysosomal degradation or nutritional sources into GlcNAc 6-phosphate (PubMed:22692205). Involved in the N-glycolylneuraminic acid (Neu5Gc) degradation pathway: although human is not able to catalyze formation of Neu5Gc due to the inactive CMAHP enzyme, Neu5Gc is present in food and must be degraded (PubMed:22692205). Also has N-acetylmannosamine (ManNAc) kinase activity (By similarity). Also involved in innate immunity by promoting detection of bacterial peptidoglycan by NOD2: acts by catalyzing phosphorylation of muramyl dipeptide (MDP), a fragment of bacterial peptidoglycan, to generate 6-O-phospho-muramyl dipeptide, which acts as a direct ligand for NOD2 (PubMed:36002575)","subcellular_location":"","url":"https://www.uniprot.org/uniprotkb/Q9UJ70/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/NAGK","classification":"Not Classified","n_dependent_lines":6,"n_total_lines":1208,"dependency_fraction":0.004966887417218543},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/NAGK","total_profiled":1310},"omim":[{"mim_id":"606828","title":"N-ACETYLGLUCOSAMINE KINASE; NAGK","url":"https://www.omim.org/entry/606828"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"},{"location":"Nucleoplasm","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/NAGK"},"hgnc":{"alias_symbol":["GNK"],"prev_symbol":[]},"alphafold":{"accession":"Q9UJ70","domains":[{"cath_id":"3.30.420.40","chopping":"3-114_308-330","consensus_level":"medium","plddt":95.1315,"start":3,"end":330}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UJ70","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UJ70-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UJ70-F1-predicted_aligned_error_v6.png","plddt_mean":94.81},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=NAGK","jax_strain_url":"https://www.jax.org/strain/search?query=NAGK"},"sequence":{"accession":"Q9UJ70","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UJ70.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UJ70/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UJ70"}},"corpus_meta":[{"pmid":"36002575","id":"PMC_36002575","title":"Phosphorylation of muramyl peptides by NAGK is required for NOD2 activation.","date":"2022","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/36002575","citation_count":60,"is_preprint":false},{"pmid":"34844667","id":"PMC_34844667","title":"Glutamine deprivation triggers NAGK-dependent hexosamine salvage.","date":"2021","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/34844667","citation_count":43,"is_preprint":false},{"pmid":"19409905","id":"PMC_19409905","title":"N-acetyl-L-glutamate kinase (NAGK) from oxygenic phototrophs: P(II) signal transduction across domains of life reveals novel insights in NAGK control.","date":"2009","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/19409905","citation_count":43,"is_preprint":false},{"pmid":"30483512","id":"PMC_30483512","title":"The PII-NAGK-PipX-NtcA Regulatory Axis of Cyanobacteria: A Tale of Changing Partners, Allosteric Effectors and Non-covalent Interactions.","date":"2018","source":"Frontiers in molecular biosciences","url":"https://pubmed.ncbi.nlm.nih.gov/30483512","citation_count":41,"is_preprint":false},{"pmid":"20399792","id":"PMC_20399792","title":"A novel signal transduction protein P(II) variant from Synechococcus elongatus PCC 7942 indicates a two-step process for NAGK-P(II) complex formation.","date":"2010","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/20399792","citation_count":35,"is_preprint":false},{"pmid":"20386738","id":"PMC_20386738","title":"On the conservation of the slow conformational dynamics within the amino acid kinase family: NAGK the paradigm.","date":"2010","source":"PLoS computational biology","url":"https://pubmed.ncbi.nlm.nih.gov/20386738","citation_count":33,"is_preprint":false},{"pmid":"21901472","id":"PMC_21901472","title":"Site-directed mutagenesis and feedback-resistant N-acetyl-L-glutamate kinase (NAGK) increase Corynebacterium crenatum L-arginine production.","date":"2011","source":"Amino acids","url":"https://pubmed.ncbi.nlm.nih.gov/21901472","citation_count":26,"is_preprint":false},{"pmid":"30904594","id":"PMC_30904594","title":"Developmental regulation of Wnt signaling by Nagk and the UDP-GlcNAc salvage pathway.","date":"2019","source":"Mechanisms of development","url":"https://pubmed.ncbi.nlm.nih.gov/30904594","citation_count":18,"is_preprint":false},{"pmid":"24349456","id":"PMC_24349456","title":"From PII signaling to metabolite sensing: a novel 2-oxoglutarate sensor that details PII-NAGK complex formation.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24349456","citation_count":18,"is_preprint":false},{"pmid":"26317540","id":"PMC_26317540","title":"Energy Sensing versus 2-Oxoglutarate Dependent ATPase Switch in the Control of Synechococcus PII Interaction with Its Targets NAGK and PipX.","date":"2015","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/26317540","citation_count":18,"is_preprint":false},{"pmid":"22101454","id":"PMC_22101454","title":"Site-directed mutagenesis studies on the L-arginine-binding sites of feedback inhibition in N-acetyl-L-glutamate kinase (NAGK) from Corynebacterium glutamicum.","date":"2011","source":"Current microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/22101454","citation_count":17,"is_preprint":false},{"pmid":"29176648","id":"PMC_29176648","title":"Evidence for PII with NAGK interaction that regulates Arg synthesis in the microalga Myrmecia incisa in response to nitrogen starvation.","date":"2017","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/29176648","citation_count":12,"is_preprint":false},{"pmid":"32896084","id":"PMC_32896084","title":"Implementation of the plasma MYCN/NAGK ratio to detect MYCN amplification in patients with neuroblastoma.","date":"2020","source":"Molecular oncology","url":"https://pubmed.ncbi.nlm.nih.gov/32896084","citation_count":6,"is_preprint":false},{"pmid":"38126036","id":"PMC_38126036","title":"g-NK cells from umbilical cord blood are phenotypically and functionally different than g-NK cells from peripheral blood.","date":"2023","source":"Oncoimmunology","url":"https://pubmed.ncbi.nlm.nih.gov/38126036","citation_count":3,"is_preprint":false},{"pmid":"39488153","id":"PMC_39488153","title":"NAGK regulates the onset of puberty in female mice.","date":"2024","source":"Theriogenology","url":"https://pubmed.ncbi.nlm.nih.gov/39488153","citation_count":0,"is_preprint":false},{"pmid":"41999177","id":"PMC_41999177","title":"The interaction between PII and NAGK regulates arginine biosynthesis in the green microalga Haematococcus pluvialis.","date":"2026","source":"Journal of phycology","url":"https://pubmed.ncbi.nlm.nih.gov/41999177","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.07.03.24309734","title":"The Optimal Prediction Model for Successful External Cephalic Version","date":"2024-07-05","source":"bioRxiv","url":"https://doi.org/10.1101/2024.07.03.24309734","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10724,"output_tokens":1272,"usd":0.025626,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":7923,"output_tokens":2007,"usd":0.044895,"stage2_stop_reason":"end_turn"},"total_usd":0.070521,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2022,\n      \"finding\": \"NAGK (N-acetylglucosamine kinase) directly phosphorylates the N-acetylmuramic acid moiety of muramyl dipeptide (MDP) at the hydroxyl group of its C6 position, yielding 6-O-phospho-MDP, which is the actual agonist for NOD2. Unmodified MDP does not activate NOD2; NAGK-phosphorylated MDP is required. Macrophages from NAGK-deficient mice are completely deficient in MDP sensing.\",\n      \"method\": \"Forward genetic screen, in vitro phosphorylation assay, NAGK knockout mice (macrophage functional assays), chemical characterization of phospho-MDP product\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct enzymatic activity demonstrated in vitro, genetic KO with defined cellular phenotype, product chemically characterized, replicated with mouse model\",\n      \"pmids\": [\"36002575\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"NAGK mediates a hexosamine salvage pathway by phosphorylating free GlcNAc to feed UDP-GlcNAc pools when de novo hexosamine synthesis is suppressed by glutamine limitation. NAGK deletion from pancreatic ductal adenocarcinoma (PDA) cells impairs tumor growth in mice.\",\n      \"method\": \"Isotope tracing/metabolomics, NAGK genetic deletion (CRISPR/KO), xenograft mouse tumor growth assay\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — metabolic flux tracing with genetic KO and in vivo tumor growth readout, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"34844667\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Nagk and the UDP-GlcNAc glycosylation salvage pathway specifically regulate Wnt signaling during vertebrate development, without affecting Fgf, TGFβ, Notch, or Shh pathways. This role is evolutionarily conserved in Xenopus, zebrafish, and Drosophila. GlcNAc is essential for growth of intestinal enteroids, which are Wnt-dependent.\",\n      \"method\": \"Kinase screen in Xenopus embryogenesis, pathway-specific reporter assays, genetic loss-of-function in zebrafish and Drosophila, intestinal enteroid growth assay\",\n      \"journal\": \"Mechanisms of development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — epistasis and pathway specificity demonstrated across multiple model organisms, single lab, phenotypic readouts without full molecular mechanism\",\n      \"pmids\": [\"30904594\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"NAGK knockdown in hypothalamic GT1-7 cells decreases transcription of Gnrh, Kiss1, Gpr54, Igf1, and Mapk14 mRNA and reduces GnRH secretion, while increasing β-catenin mRNA and apoptosis. In vivo, intracerebroventricular Nagk knockdown delays vaginal opening and reduces hypothalamic Gnrh and Kiss1 mRNA levels and serum E2 in female mice, establishing a role for NAGK in regulating puberty onset.\",\n      \"method\": \"siRNA knockdown in GT1-7 cells, RT-qPCR, GnRH secretion assay, ICV injection knockdown in mice, immunofluorescence, serum hormone measurement\",\n      \"journal\": \"Theriogenology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — genetic loss-of-function with defined cellular and in vivo phenotypic readouts, single lab, limited mechanistic pathway resolution\",\n      \"pmids\": [\"39488153\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"Human/mammalian NAGK (N-acetylglucosamine kinase) functions as a metabolic kinase with at least two distinct mechanistic roles: (1) it directly phosphorylates the C6-OH of the N-acetylmuramic acid moiety of muramyl dipeptide (MDP), generating 6-O-phospho-MDP, which is the obligate NOD2 agonist required for innate immune sensing of bacterial peptidoglycan; and (2) it phosphorylates free GlcNAc in the hexosamine salvage pathway to replenish UDP-GlcNAc pools under nutrient-limited conditions, supporting glycosylation and cell growth; additionally, NAGK activity in the salvage pathway specifically supports Wnt signaling during development and regulates hypothalamic GnRH/Kiss1 expression and puberty onset.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"NAGK (N-acetylglucosamine kinase) is a metabolic sugar kinase with dual roles in innate immunity and hexosamine salvage metabolism [#0, #1]. In immune sensing, NAGK directly phosphorylates the C6 hydroxyl of the N-acetylmuramic acid moiety of muramyl dipeptide (MDP), generating 6-O-phospho-MDP; this phosphorylated species, not unmodified MDP, is the agonist that activates NOD2, and NAGK-deficient macrophages are completely unable to sense MDP [#0]. In parallel, NAGK phosphorylates free GlcNAc to feed UDP-GlcNAc pools through a hexosamine salvage pathway that becomes critical when de novo synthesis is limited by glutamine restriction, a dependence exploited by pancreatic ductal adenocarcinoma cells for tumor growth [#1]. This salvage-derived UDP-GlcNAc supply specifically supports Wnt signaling during vertebrate development, conserved across Xenopus, zebrafish, and Drosophila and required for Wnt-dependent intestinal enteroid growth [#2]. In the hypothalamus, NAGK supports transcription of Gnrh and Kiss1 and GnRH secretion, and its knockdown delays puberty onset in female mice [#3].\",\n  \"teleology\": [\n    {\n      \"year\": 2019,\n      \"claim\": \"Establishing whether NAGK has a developmental signaling role beyond housekeeping metabolism, this work showed that NAGK-dependent UDP-GlcNAc salvage selectively gates Wnt signaling.\",\n      \"evidence\": \"Kinase screen in Xenopus embryogenesis with pathway-specific reporters, genetic loss-of-function in zebrafish and Drosophila, and Wnt-dependent intestinal enteroid growth assay\",\n      \"pmids\": [\"30904594\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Molecular link between UDP-GlcNAc levels and Wnt pathway specificity not resolved\", \"Direct glycosylation target mediating Wnt dependence not identified\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Defining the metabolic context where NAGK matters, this study showed that NAGK enables a hexosamine salvage route feeding UDP-GlcNAc when de novo synthesis is suppressed, supporting tumor growth.\",\n      \"evidence\": \"Isotope tracing/metabolomics with CRISPR/KO of NAGK and xenograft tumor growth in mice\",\n      \"pmids\": [\"34844667\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Downstream glycoproteins dependent on salvage flux not enumerated\", \"Generalizability beyond pancreatic ductal adenocarcinoma not established\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Resolving the long-standing question of how cytosolic peptidoglycan fragments are recognized, this work identified NAGK as the kinase that converts MDP into the true NOD2 agonist.\",\n      \"evidence\": \"Forward genetic screen, in vitro phosphorylation assay, chemical characterization of 6-O-phospho-MDP, and NAGK knockout mouse macrophage functional assays\",\n      \"pmids\": [\"36002575\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Structural basis of MDP recognition by NAGK not defined\", \"How 6-O-phospho-MDP engages NOD2 mechanistically not detailed\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Extending NAGK into neuroendocrine control, this study linked NAGK activity to hypothalamic GnRH/Kiss1 programs and puberty timing.\",\n      \"evidence\": \"siRNA knockdown in GT1-7 cells with RT-qPCR and GnRH secretion assays, plus ICV knockdown in mice with hormone measurement and immunofluorescence\",\n      \"pmids\": [\"39488153\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Causal pathway from NAGK kinase activity to Gnrh/Kiss1 transcription not mapped\", \"Relationship between observed β-catenin/Wnt changes and the GnRH phenotype unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Whether NAGK's metabolic salvage activity and its peptidoglycan-sensing activity are mechanistically coupled, and how a single sugar kinase coordinates these distinct outputs, remains open.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No unified structural/regulatory model linking the GlcNAc-salvage and MDP-phosphorylation activities\", \"Tissue-specific control of which NAGK function dominates is uncharacterized\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0016301\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"NOD2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}