Affinage

NAGK

N-acetyl-D-glucosamine kinase · UniProt Q9UJ70

Round 2 corrected
Length
344 aa
Mass
37.4 kDa
Annotated
2026-04-29
46 papers in source corpus 4 papers cited in narrative 4 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

NAGK (N-acetyl-D-glucosamine kinase) is a sugar kinase that phosphorylates GlcNAc to GlcNAc-6-phosphate, feeding the hexosamine salvage pathway to maintain UDP-GlcNAc pools essential for glycosylation; under glutamine limitation, pancreatic cancer cells depend on this NAGK-driven salvage route for tumor growth (PMID:34844667). Beyond its canonical sugar kinase activity, NAGK directly phosphorylates the N-acetylmuramic acid moiety of muramyl dipeptide (MDP) at C6, generating 6-O-phospho-MDP as the obligate NOD2 agonist required for innate immune sensing of bacterial peptidoglycan (PMID:36002575). The UDP-GlcNAc salvage pathway including NAGK selectively promotes Wnt signaling during embryonic anteroposterior patterning, a role conserved across vertebrates and Drosophila (PMID:30904594).

Mechanistic history

Synthesis pass · year-by-year structured walk · 4 steps
  1. 2019 Medium

    It was unknown whether hexosamine salvage enzymes including NAGK had signaling-pathway-specific roles during development; a cross-species screen demonstrated that the NAGK-dependent salvage pathway selectively promotes Wnt signaling without affecting Fgf, TGFβ, Notch, or Shh, establishing a non-metabolic developmental function for the pathway.

    Evidence Human kinase screen in Xenopus embryos with morpholino knockdown, validated in zebrafish and Drosophila, plus intestinal enteroid culture

    PMID:30904594

    Open questions at the time
    • The specific glycosylation substrate(s) mediating Wnt sensitivity downstream of UDP-GlcNAc remain unidentified
    • Whether NAGK enzymatic activity per se or a scaffolding role drives the Wnt effect is unresolved
  2. 2021 High

    It was unclear how cancer cells sustain UDP-GlcNAc pools under glutamine deprivation; isotope tracing and genetic deletion showed that NAGK phosphorylates free GlcNAc to bypass the glutamine-dependent de novo hexosamine biosynthesis pathway, and this salvage route is required for pancreatic tumor growth.

    Evidence Isotope tracing metabolomics, NAGK genetic deletion in PDA cell lines, and xenograft mouse models

    PMID:34844667

    Open questions at the time
    • Source of free GlcNAc in the tumor microenvironment not fully defined
    • Whether other sugar kinases partially compensate for NAGK loss in non-pancreatic contexts is untested
  3. 2022 High

    The biochemical basis for NOD2 activation by muramyl dipeptide was incomplete; a forward genetic screen and reconstituted enzymatic assays revealed that NAGK phosphorylates MDP at the C6 hydroxyl of its MurNAc moiety, and this 6-O-phospho-MDP—not unmodified MDP—is the true NOD2 agonist, establishing NAGK as an essential upstream checkpoint in innate immune sensing.

    Evidence Forward genetic screen, in vitro phosphorylation assay with chemical characterization of product, NAGK-KO mouse macrophages

    PMID:36002575

    Open questions at the time
    • Structural basis for how 6-O-phospho-MDP binds NOD2 versus unmodified MDP not determined
    • Whether NAGK processes other bacterial glycan fragments remains unexplored
  4. 2024 Medium

    Whether NAGK has roles in neuroendocrine regulation was unknown; knockdown studies in hypothalamic cells and in vivo in female mice showed that NAGK is required for normal GnRH and Kisspeptin expression and timely puberty onset.

    Evidence siRNA knockdown in GT1-7 hypothalamic cells and intracerebroventricular knockdown in female mice with measurement of GnRH, Kiss1, and serum estradiol

    PMID:39488153

    Open questions at the time
    • The molecular mechanism linking NAGK kinase activity to GnRH/Kiss1 transcription is not established
    • Whether the effect proceeds through UDP-GlcNAc-dependent glycosylation or an independent function is unknown
    • Single study without independent replication

Open questions

Synthesis pass · forward-looking unresolved questions
  • It remains unresolved how NAGK's catalytic activity is partitioned between GlcNAc phosphorylation and MDP phosphorylation in different cell types, and whether its developmental and neuroendocrine roles are mechanistically downstream of UDP-GlcNAc supply, NOD2 activation, or a yet-uncharacterized activity.
  • No structural model of NAGK bound to MDP or GlcNAc in a mammalian context
  • Cell-type-specific regulation of NAGK expression and substrate preference not mapped
  • No interactome or post-translational modification landscape for NAGK itself

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0016740 transferase activity 2
Localization
GO:0005829 cytosol 1
Pathway
R-HSA-1430728 Metabolism 1 R-HSA-162582 Signal Transduction 1 R-HSA-168256 Immune System 1
Partners
NOD2

Evidence

Reading pass · 4 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2022 NAGK (N-acetylglucosamine kinase) was identified as essential for NOD2-mediated innate immune signaling. Mechanistically, NAGK directly phosphorylates the N-acetylmuramic acid moiety of muramyl dipeptide (MDP) at the C6 hydroxyl position, yielding 6-O-phospho-MDP. This phosphorylated form—not unmodified MDP—is the actual agonist for NOD2. Macrophages from NAGK-deficient mice are completely deficient in MDP sensing. Forward genetic screen; in vitro phosphorylation assay; genetic KO mouse macrophages; structural/chemical characterization of phospho-MDP product Nature High 36002575
2021 Under glutamine limitation, pancreatic ductal adenocarcinoma (PDA) cells engage NAGK-dependent hexosamine salvage to maintain UDP-GlcNAc pools. Free GlcNAc is phosphorylated by NAGK to feed the hexosamine biosynthesis pathway, bypassing the de novo route that requires glutamine. NAGK deletion from PDA cells impairs tumor growth in mice. Isotope tracing metabolomics; NAGK genetic deletion in cell lines and xenograft mouse models; NAGK overexpression analysis in human PDA datasets eLife High 34844667
2019 Nagk and other UDP-GlcNAc salvage pathway components were identified as regulators of Wnt signaling during Xenopus laevis embryogenesis. The salvage pathway selectively affects anteroposterior patterning via Wnt signaling without affecting Fgf, TGFβ, Notch, or Shh pathways. This role is evolutionarily conserved in zebrafish and Drosophila, and GlcNAc is essential for growth of Wnt-dependent intestinal enteroids. Human kinase screen in Xenopus embryos; morpholino/genetic knockdown; reporter assays for multiple signaling pathways; zebrafish and Drosophila genetic validation; intestinal enteroid culture Mechanisms of development Medium 30904594
2024 NAGK is expressed in the hypothalamic-pituitary-ovarian axis of female mice and regulates puberty onset. Nagk knockdown in GT1-7 hypothalamic cells decreased Gnrh, Kiss1, Gpr54, Igf1, and Mapk14 mRNA levels, reduced GnRH secretion, and increased apoptosis. Intracerebroventricular Nagk knockdown in vivo delayed vaginal opening and reduced hypothalamic Gnrh and Kiss1 mRNA and serum estradiol. RT-qPCR; immunofluorescence; siRNA knockdown in GT1-7 cells; ICV injection of knockdown construct in female mice; measurement of GnRH/Kisspeptin levels and reproductive hormones Theriogenology Medium 39488153

Source papers

Stage 0 corpus · 46 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2005 Towards a proteome-scale map of the human protein-protein interaction network. Nature 2090 16189514
1997 IKK-1 and IKK-2: cytokine-activated IkappaB kinases essential for NF-kappaB activation. Science (New York, N.Y.) 1784 9346484
2001 TAK1 is a ubiquitin-dependent kinase of MKK and IKK. Nature 1723 11460167
2002 Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences. Proceedings of the National Academy of Sciences of the United States of America 1479 12477932
2015 The BioPlex Network: A Systematic Exploration of the Human Interactome. Cell 1118 26186194
2017 Architecture of the human interactome defines protein communities and disease networks. Nature 1085 28514442
2014 A proteome-scale map of the human interactome network. Cell 977 25416956
2020 A reference map of the human binary protein interactome. Nature 849 32296183
2009 Involvement of linear polyubiquitylation of NEMO in NF-kappaB activation. Nature cell biology 801 19136968
2003 Complete sequencing and characterization of 21,243 full-length human cDNAs. Nature genetics 754 14702039
2021 Dual proteome-scale networks reveal cell-specific remodeling of the human interactome. Cell 705 33961781
2011 Phylogenetic-based propagation of functional annotations within the Gene Ontology consortium. Briefings in bioinformatics 656 21873635
2008 Large-scale proteomics and phosphoproteomics of urinary exosomes. Journal of the American Society of Nephrology : JASN 607 19056867
1994 Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides. Gene 492 8125298
2003 Exploring proteomes and analyzing protein processing by mass spectrometric identification of sorted N-terminal peptides. Nature biotechnology 485 12665801
1992 Selection of optimal kappa B/Rel DNA-binding motifs: interaction of both subunits of NF-kappa B with DNA is required for transcriptional activation. Molecular and cellular biology 471 1406630
2015 Widespread macromolecular interaction perturbations in human genetic disorders. Cell 454 25910212
2004 The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). Genome research 438 15489334
2007 A critical role of RICK/RIP2 polyubiquitination in Nod-induced NF-kappaB activation. The EMBO journal 429 18079694
2005 Diversification of transcriptional modulation: large-scale identification and characterization of putative alternative promoters of human genes. Genome research 409 16344560
2015 Panorama of ancient metazoan macromolecular complexes. Nature 407 26344197
2017 Synergistic drug combinations for cancer identified in a CRISPR screen for pairwise genetic interactions. Nature biotechnology 378 28319085
2012 The ubiquitin ligase XIAP recruits LUBAC for NOD2 signaling in inflammation and innate immunity. Molecular cell 326 22607974
2012 A high-throughput approach for measuring temporal changes in the interactome. Nature methods 273 22863883
2011 A directed protein interaction network for investigating intracellular signal transduction. Science signaling 258 21900206
2004 Functional proteomics mapping of a human signaling pathway. Genome research 247 15231748
2013 OTULIN restricts Met1-linked ubiquitination to control innate immune signaling. Molecular cell 217 23806334
1999 Targeting of p38 mitogen-activated protein kinases to MEF2 transcription factors. Molecular and cellular biology 213 10330143
2011 Toward an understanding of the protein interaction network of the human liver. Molecular systems biology 207 21988832
2011 Next-generation sequencing to generate interactome datasets. Nature methods 200 21516116
2022 Phosphorylation of muramyl peptides by NAGK is required for NOD2 activation. Nature 59 36002575
2021 Glutamine deprivation triggers NAGK-dependent hexosamine salvage. eLife 43 34844667
2009 N-acetyl-L-glutamate kinase (NAGK) from oxygenic phototrophs: P(II) signal transduction across domains of life reveals novel insights in NAGK control. Journal of molecular biology 43 19409905
2018 The PII-NAGK-PipX-NtcA Regulatory Axis of Cyanobacteria: A Tale of Changing Partners, Allosteric Effectors and Non-covalent Interactions. Frontiers in molecular biosciences 40 30483512
2010 A novel signal transduction protein P(II) variant from Synechococcus elongatus PCC 7942 indicates a two-step process for NAGK-P(II) complex formation. Journal of molecular biology 35 20399792
2010 On the conservation of the slow conformational dynamics within the amino acid kinase family: NAGK the paradigm. PLoS computational biology 33 20386738
2011 Site-directed mutagenesis and feedback-resistant N-acetyl-L-glutamate kinase (NAGK) increase Corynebacterium crenatum L-arginine production. Amino acids 26 21901472
2019 Developmental regulation of Wnt signaling by Nagk and the UDP-GlcNAc salvage pathway. Mechanisms of development 18 30904594
2015 Energy Sensing versus 2-Oxoglutarate Dependent ATPase Switch in the Control of Synechococcus PII Interaction with Its Targets NAGK and PipX. PloS one 18 26317540
2013 From PII signaling to metabolite sensing: a novel 2-oxoglutarate sensor that details PII-NAGK complex formation. PloS one 18 24349456
2011 Site-directed mutagenesis studies on the L-arginine-binding sites of feedback inhibition in N-acetyl-L-glutamate kinase (NAGK) from Corynebacterium glutamicum. Current microbiology 17 22101454
2017 Evidence for PII with NAGK interaction that regulates Arg synthesis in the microalga Myrmecia incisa in response to nitrogen starvation. Scientific reports 12 29176648
2020 Implementation of the plasma MYCN/NAGK ratio to detect MYCN amplification in patients with neuroblastoma. Molecular oncology 6 32896084
2023 g-NK cells from umbilical cord blood are phenotypically and functionally different than g-NK cells from peripheral blood. Oncoimmunology 3 38126036
2026 The interaction between PII and NAGK regulates arginine biosynthesis in the green microalga Haematococcus pluvialis. Journal of phycology 0 41999177
2024 NAGK regulates the onset of puberty in female mice. Theriogenology 0 39488153