AZI2 (5-azacytidine-induced protein 2), better known as NAP1 (NAK-associated protein 1; also TBKBP2, TILP), is a cytoplasmic adapter protein that binds and positively regulates the IkappaB kinase (IKK)-related serine/threonine kinases TBK1 (NAK) and IKBKE (IKKepsilon). The protein has an N-terminal homodimerization region and two coiled-coil segments, and a C-terminal TBK1/IKBKE-binding domain (the Pfam TBD module, residues ~216-257) shared with the related adapters TANK and TBKBP1/SINTBAD. By binding TBK1, NAP1 promotes TBK1 activation and oligomerization and thereby couples upstream innate-immune signals to TBK1 kinase output. NAP1 functions as a shared adaptor in type I interferon induction downstream of both the endosomal Toll-like receptor 3 (via the TRIF/TICAM1 adaptor) and the cytoplasmic RIG-I/MDA5 RNA-sensing pathway, driving IRF3 activation and IFN-beta production, and it also potentiates NF-kappaB activation, including TBK1-dependent phosphorylation of the p65/RELA subunit. NAP1 is a constituent of the TBK1-IKKepsilon-NAP1 complex. Structurally, its N-terminal region binds the SKICH domains of the selective-autophagy cargo receptors NDP52/CALCOCO2 and TAX1BP1, allowing NAP1 (with its paralog SINTBAD) to bridge these receptors to TBK1 and recruit/ activate TBK1 at autophagic cargo. NAP1 is itself a phosphoprotein and is subject to TRIM38-mediated K48-linked polyubiquitination and degradation.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
|
GO:0005737
cytoplasm
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: Phylogenetic (PAN-GO) inference that NAP1 is active in the cytoplasm, consistent with experimental localization and its cytoplasmic adaptor role for TBK1/IKBKE.
Reason: Correct core compartment; NAP1 acts as a cytoplasmic adaptor that binds and activates TBK1, consistent with the experimental cytoplasmic localization (PMID:14560022).
Supporting Evidence:
file:human/AZI2/AZI2-uniprot.txt
SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:14560022}.
|
|
GO:0005737
cytoplasm
|
IEA
GO_REF:0000120 |
ACCEPT |
Summary: Electronic transfer of cytoplasmic localization (UniProt subcellular location / mouse ortholog), redundant with but consistent with the experimental and IBA cytoplasm annotations.
Reason: Correct core cytoplasmic localization; redundant electronic assignment that agrees with the EXP (PMID:14560022) and IBA evidence.
Supporting Evidence:
file:human/AZI2/AZI2-uniprot.txt
SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:14560022}.
|
|
GO:0005515
protein binding
|
IPI
PMID:14743216 A physical and functional map of the human TNF-alpha/NF-kapp... |
KEEP AS NON CORE |
Summary: IntAct interaction with TBK1 (Q9UHD2) from a TNF-alpha/NF-kappaB pathway interaction map. Records the functionally central TBK1 interaction but bare protein binding is uninformative.
Reason: Captures the key NAP1-TBK1 interaction underlying its adaptor function, but bare protein binding (GO:0005515) is uninformative per curation guidelines; the functional MF/CC is better captured by the kinase-complex and IFN annotations.
Supporting Evidence:
file:human/AZI2/AZI2-uniprot.txt
Q9H6S1; Q9UHD2: TBK1; NbExp=7; IntAct=EBI-359973, EBI-356402;
|
|
GO:0005515
protein binding
|
IPI
PMID:21903422 Mapping a dynamic innate immunity protein interaction networ... |
KEEP AS NON CORE |
Summary: IntAct interaction with TBK1 (Q9UHD2) from a dynamic innate-immunity (type I IFN) interaction network. Bare protein binding is uninformative.
Reason: Records the real NAP1-TBK1 interaction in the type I IFN network but bare protein binding is uninformative.
Supporting Evidence:
file:human/AZI2/AZI2-uniprot.txt
Q9H6S1; Q9UHD2: TBK1; NbExp=7; IntAct=EBI-359973, EBI-356402;
|
|
GO:0005515
protein binding
|
IPI
PMID:21931555 Vaccinia virus protein C6 is a virulence factor that binds T... |
KEEP AS NON CORE |
Summary: IntAct interactions from the vaccinia virus C6 study (NAP1 binds vaccinia C6/OPG029 and TBK1). C6 is a viral antagonist that targets TBK1 adaptors to block IRF3/IRF7. Bare protein binding is uninformative.
Reason: Records a real host-virus interaction (vaccinia C6 targeting NAP1 as a TBK1 adaptor) and the TBK1 interaction, but bare protein binding is uninformative.
Supporting Evidence:
file:human/AZI2/AZI2-uniprot.txt
Q9H6S1; P17362: OPG029; Xeno; NbExp=2; IntAct=EBI-359973, EBI-9519257;
|
|
GO:0005515
protein binding
|
IPI
PMID:22014111 Flavivirus NS3 and NS5 proteins interaction network: a high-... |
KEEP AS NON CORE |
Summary: IntAct interaction with a flavivirus protein (Q9E7P0) from a flavivirus NS3/NS5 yeast two-hybrid screen. Bare protein binding is uninformative.
Reason: High-throughput host-virus Y2H interaction; bare protein binding is uninformative and the interaction is not central to the core function.
Supporting Evidence:
file:human/AZI2/AZI2-uniprot.txt
Q9H6S1; Q9E7P0; Xeno; NbExp=2; IntAct=EBI-359973, EBI-11361108;
|
|
GO:0005515
protein binding
|
IPI
PMID:29251827 Quantitative Proteomics Identified TTC4 as a TBK1 Interactor... |
KEEP AS NON CORE |
Summary: IntAct interaction with TBK1 (Q9UHD2) from the TBK1/STING/MDA5 interactome (TTC4 study). Bare protein binding is uninformative.
Reason: Records the NAP1-TBK1 interaction in the antiviral innate-immune interactome but bare protein binding is uninformative.
Supporting Evidence:
file:human/AZI2/AZI2-uniprot.txt
Q9H6S1; Q9UHD2: TBK1; NbExp=7; IntAct=EBI-359973, EBI-356402;
|
|
GO:0005515
protein binding
|
IPI
PMID:32707033 Kinase Interaction Network Expands Functional and Disease Ro... |
KEEP AS NON CORE |
Summary: IntAct interaction with TBK1 (Q9UHD2) from a human kinase interaction network. Bare protein binding is uninformative.
Reason: Records the NAP1-TBK1 interaction but bare protein binding is uninformative.
Supporting Evidence:
file:human/AZI2/AZI2-uniprot.txt
Q9H6S1; Q9UHD2: TBK1; NbExp=7; IntAct=EBI-359973, EBI-356402;
|
|
GO:0043124
negative regulation of canonical NF-kappaB signal transduction
|
IEA
GO_REF:0000107 |
KEEP AS NON CORE |
Summary: Ensembl Compara transfer from the mouse ortholog (Q9QYP6) of a negative regulation of canonical NF-kappaB role. The human-characterized role of NAP1 is predominantly to potentiate NF-kappaB (PMID:14560022), so this orthology-based term is at best context-specific and conflicts with the dominant positive-regulatory role.
Reason: Orthology-transferred (mouse) annotation; not contradicted by clearly identified human evidence so retained, but the dominant, experimentally characterized human role is positive regulation/potentiation of NF-kappaB, so this negative-regulation term is non-core and possibly context-specific.
Supporting Evidence:
file:human/AZI2/AZI2-uniprot.txt
Promotes TBK1-induced as well as TNF or PMA-induced activation of NF-kappa-B
|
|
GO:0005737
cytoplasm
|
EXP
PMID:14560022 Identification of NAP1, a regulatory subunit of IkappaB kina... |
ACCEPT |
Summary: Experimental evidence that NAP1 localizes to the cytoplasm (foundational identification paper). Core localization where NAP1 binds and activates TBK1/IKBKE.
Reason: Experimentally supported core cytoplasmic localization, the compartment in which NAP1 acts as a TBK1/IKBKE adaptor.
Supporting Evidence:
file:human/AZI2/AZI2-uniprot.txt
SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:14560022}.
|
|
GO:0051607
defense response to virus
|
NAS
PMID:17142768 NAK-associated protein 1 participates in both the TLR3 and t... |
ACCEPT |
Summary: ComplexPortal author-statement (TBK1-IKKepsilon-NAP1 complex, CPX-6038) that NAP1 participates in antiviral defense. NAP1 acts as a shared adaptor downstream of TLR3 and the cytoplasmic RIG-I/MDA5 pathway in type I IFN induction.
Reason: Core biological process; NAP1 is an established adaptor in antiviral innate immunity feeding IRF3 activation and IFN-beta induction via both TLR3/TRIF and the cytoplasmic RNA-sensing pathways. Recent literature compiled in the falcon deep-research report reinforces NAP1 as a positive regulator of the TBK1-IRF3/IRF7 type I IFN axis downstream of the major nucleic-acid sensing pathways, although the specific sensor branches (RLR-MAVS, cGAS-STING, TLR3-TRIF) are general TBK1-pathway context rather than uniquely AZI2-specific findings.
Supporting Evidence:
file:human/AZI2/AZI2-uniprot.txt
Adapter protein which binds TBK1 and IKBKE playing a role in antiviral innate immunity
PMID:17142768
NAK-associated protein 1 participates in both the TLR3 and the cytoplasmic pathways in type I IFN induction
file:human/AZI2/AZI2-deep-research-falcon.md
NAP1 is critical for linking TBK1 to IRF3/IRF7 and the type I interferon response, acting downstream of RLR–MAVS, cGAS–STING, and TLR3–TRIF pathways.
|
|
GO:0060337
type I interferon-mediated signaling pathway
|
NAS
PMID:17142768 NAK-associated protein 1 participates in both the TLR3 and t... |
KEEP AS NON CORE |
Summary: ComplexPortal author-statement that NAP1 (in the TBK1-IKKepsilon-NAP1 complex) participates in type I interferon signaling/induction. NAP1 couples TLR3 and cytoplasmic RNA sensing to IRF3/type I IFN.
Reason: NAP1's documented role is in type I IFN induction (driving IRF3 activation and IFN-beta production upstream), rather than in the downstream IFN-receptor (JAK/STAT) signaling that GO:0060337 (type I interferon-mediated signaling pathway) most precisely denotes; retained as a correct but imprecise pathway-context annotation. The defense-response-to-virus and IFN-beta-production-related roles are the core capture.
Supporting Evidence:
PMID:17142768
NAK-associated protein 1 participates in both the TLR3 and the cytoplasmic pathways in type I IFN induction
|
|
GO:1902554
serine/threonine protein kinase complex
|
NAS
PMID:17142768 NAK-associated protein 1 participates in both the TLR3 and t... |
ACCEPT |
Summary: ComplexPortal author-statement that NAP1 is part of a serine/threonine protein kinase complex (the TBK1-IKKepsilon-NAP1 complex, CPX-6038). Core cellular component capturing NAP1's defining role as a subunit of the TBK1/IKBKE kinase complex.
Reason: Core cellular component; NAP1 is a constituent/regulatory subunit of the TBK1-IKKepsilon kinase complex, which is the structural basis of its adaptor and kinase-activating function. The falcon deep-research report corroborates the mechanistic basis, with NAP1 binding promoting TBK1 activation via Ser172 autophosphorylation.
Supporting Evidence:
file:human/AZI2/AZI2-uniprot.txt
Activates serine/threonine-protein kinase TBK1 and facilitates its oligomerization
file:human/AZI2/AZI2-deep-research-falcon.md
It binds and activates TANK-binding kinase 1 (TBK1), inducing conformational changes that enable TBK1 autophosphorylation at Ser172—essential for kinase activation
|
Q: Does human NAP1 have a genuine negative-regulatory role in canonical NF-kappaB signaling (as inferred by orthology from mouse), or is the IEA GO:0043124 annotation context-specific given that the foundational human study shows NAP1 potentiates NF-kappaB?
Q: How is NAP1's adaptor activity partitioned between TBK1 activation in antiviral type I IFN induction and TBK1 recruitment to NDP52/TAX1BP1 in selective autophagy, and do its four isoforms (which differ in the TBK1-binding region) have distinct functions?
Q: Recent primary literature (compiled in the falcon deep-research report but not yet reflected in GOA) implicates AZI2/NAP1 in TBK1 activation at centrosomes during mitosis/cytokinesis (Paul et al. 2023), in selective autophagy/mitophagy via OPTN/NDP52 and FIP200/RB1CC1 (Adriaenssens et al. 2024; Yeo et al. 2024), and in a TBK1-dependent TNF-receptor cell-death checkpoint with TANK (Ujevic et al. 2024). Should these become curated GO annotations (e.g. mitotic cell cycle, macroautophagy/mitophagy, negative regulation of programmed cell death), and which are AZI2-specific versus shared TBK1-adaptor functions?
Experiment: Reconstitute TBK1 activation in vitro with purified TBK1 and wild-type versus TBK1-binding-domain (residues 216-257) mutant NAP1 to quantify how NAP1 promotes TBK1 trans-autophosphorylation and oligomerization, and test substrate phosphorylation (IRF3, p65/RELA).
Experiment: Use NAP1 (AZI2) knockout cells reconstituted with isoform-specific or domain-mutant constructs to dissect NAP1's contribution to TLR3- versus RIG-I/MDA5-driven IFN-beta induction and to NDP52/TAX1BP1-dependent selective autophagy/xenophagy.
The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.
We are interested in where in or outside the cell the gene product carries out its function.
We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.
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| Aspect | Summary for AZI2/NAP1 | Key evidence / mechanistic detail | Citations |
|---|---|---|---|
| Verified identity | Human AZI2 encodes 5-azacytidine-induced protein 2, also called NAK-associated protein 1 (NAP1), a TBK1 adaptor protein. | Recent literature explicitly equates AZI2 with NAP1 and studies it in human cell systems in innate immunity, autophagy, mitosis, and TNF signaling. | (paul2023nakassociatedprotein1nap1 pages 1-2, yeo2024azi2mediatestbk1 pages 1-2, ujevic2024tbk1associatedadapterstank pages 1-2) |
| Primary molecular function | Scaffold/adaptor for TBK1 rather than an enzyme or transporter. | AZI2 binds TBK1 and promotes its activation by adaptor-driven assembly/oligomerization and TBK1 Ser172 autophosphorylation; it links TBK1 to different signaling platforms and cargo receptor complexes. | (paul2023nakassociatedprotein1nap1 pages 1-2, zhou2020tbk1acentral pages 1-2, zhou2020tbk1acentral pages 2-3) |
| TBK1-binding role | AZI2 directly engages the TBK1 adaptor-binding region through its own TBK1-binding domain (TBD). | Reviews and mechanistic studies describe a central TBD in NAP1/AZI2 that associates with the C-terminal adaptor-binding domain of TBK1; adaptor competition with TANK/SINTBAD helps specify pathway usage. | (glon2025nap1switchesfrom pages 1-5, zhou2020tbk1acentral pages 2-3) |
| Structural features / domains | Modular coiled-coil adaptor with homodimerization region, central TBD, intrinsically disordered regions, and a FIP200-binding region (FIR) used in selective autophagy. | NAP1/AZI2 is described as one of three homologous TBK1 adaptors; structural work resolved NAP1 FIR interaction with RB1CC1/FIP200 and places NAP1 in NDP52–TBK1–FIP200 assemblies. | (glon2025nap1switchesfrom pages 1-5, fu2021structuralandbiochemical pages 1-2) |
| Type I IFN pathway | AZI2 is a positive regulator of TBK1–IRF3/IRF7 signaling for type I interferon induction. | TBK1 is the central kinase downstream of RLR-MAVS, cGAS-STING, and TLR3/TRIF; AZI2/NAP1 is one of the key TBK1 adaptors that helps activate this axis. In some contexts, AZI2 also promotes DDX3X–IRF3 signaling and pro-inflammatory chemokine transcription. | (yeo2024azi2mediatestbk1 pages 1-2, zhou2020tbk1acentral pages 1-2, yeo2024azi2mediatestbk1 pages 2-4) |
| TNF signaling pathway | AZI2 helps recruit TBK1 to the TNF receptor signaling complex to restrain inflammatory cell death. | In 2024 work, AZI2 and TANK cooperatively sustained TBK1 activation in TNF signaling; AZI2 was recruited later via A20, enabling TBK1-dependent suppression of RIPK1-driven apoptosis/necroptosis and limiting excessive NF-κB pathway activation. | (ujevic2024tbk1associatedadapterstank pages 1-2, ujevic2024tbk1associatedadapterstank pages 2-3) |
| Selective autophagy pathway | AZI2 bridges cargo receptors to TBK1 and promotes selective autophagy execution. | NDP52 binds NAP1/SINTBAD, which recruit TBK1; NAP1 also engages FIP200/RB1CC1, integrating TBK1 and ULK/FIP200 modules at cargo. Structural work shows competitive interactions among NAP1, RB1CC1, and ATG8-family proteins. | (fu2021structuralandbiochemical pages 1-2, adriaenssens2024controlofmitophagy pages 2-3) |
| Mitophagy control | AZI2 acts as a context-dependent rheostat in mitophagy. | Under PINK1/Parkin mitophagy, NAP1/SINTBAD can inhibit OPTN-driven initiation by competing for TBK1, yet support NDP52-driven progression by recruiting TBK1 and stabilizing NDP52–FIP200 interactions. Artificial mitochondrial tethering of NAP1 was sufficient to induce mitophagy-like responses. | (adriaenssens2024controlofmitophagy pages 1-2, adriaenssens2024controlofmitophagy pages 2-3, adriaenssens2024controlofmitophagy pages 3-4) |
| Mitosis and cytokinesis | AZI2 is required for TBK1 activation during cell division and supports accurate mitosis/cytokinesis. | NAP1/AZI2 localizes with TBK1 at centrosomes; loss of NAP1 reduces mitotic p-TBK1 and causes slower growth, binucleation/multinucleation, spindle defects, lagging chromosomes, and cytokinetic abnormalities. | (paul2023nakassociatedprotein1nap1 pages 1-2, paul2023nakassociatedprotein1nap1 pages 2-5) |
| Cell-death control | AZI2 contributes to a cell-death checkpoint by supporting TBK1 anti-death signaling. | In TNF signaling, AZI2 enables TBK1-mediated inhibition of RIPK1 activation; in AML-related work, NAP1 also interacted with PTPN23 to facilitate endosomal sorting of TNFR1 and influence sensitivity to TNFα-induced cytotoxicity. | (ujevic2024tbk1associatedadapterstank pages 1-2, song2024ptpn23dependentescrtmachinery pages 1-2, ujevic2024tbk1associatedadapterstank pages 2-3) |
| Cancer-related implementation | AZI2-TBK1 signaling can be exploited to increase tumor immunogenicity and CD8 T-cell infiltration. | In breast cancer models, RB1CC1/FIP200 loss caused AZI2 puncta, TBK1 activation, DDX3X–IRF3 signaling, chemokine induction, and increased CD8+ T-cell infiltration; Lys05 was identified as a pharmacologic inducer of this pathway. | (yeo2024azi2mediatestbk1 pages 1-2, okamoto2020fip200suppressesimmune pages 1-3, yeo2024azi2mediatestbk1 pages 2-4) |
| Basal subcellular localization | Predominantly diffuse cytosolic under unstimulated conditions. | Mitophagy and condensate studies report NAP1/SINTBAD dispersed through the cytosol before pathway induction. | (adriaenssens2024controlofmitophagy pages 2-3) |
| Localization in mitosis | Centrosomes and associated spindle structures. | NAP1 is described as a centrosomal protein required for local TBK1 activation during mitosis; activated TBK1 signal extends across centrosome/spindle regions. | (paul2023nakassociatedprotein1nap1 pages 1-2, paul2023nakassociatedprotein pages 9-12) |
| Localization in mitophagy | Recruited to depolarized mitochondria and early autophagosome initiation sites. | Upon oligomycin/antimycin treatment, HA-NAP1 accumulated on damaged mitochondria and colocalized with WIPI2, indicating function at phagophore initiation sites. | (adriaenssens2024controlofmitophagy pages 2-3) |
| Localization in selective-autophagy blockade | Forms cytoplasmic AZI2 puncta with active TBK1, ubiquitin, and cargo receptors. | RB1CC1 depletion caused AZI2 puncta that colocalized with p-TBK1, SQSTM1/p62, TAX1BP1, NBR1, OPTN, and ubiquitin, supporting a role at unresolved cargo receptor complexes rather than generic bulk autophagy structures. | (yeo2024azi2mediatestbk1 pages 1-2, yeo2024azi2mediatestbk1 pages 2-4) |
| Localization in innate immune signaling | Present in cytoplasmic liquid-like condensates after danger signaling. | Endogenous NAP1, SINTBAD, TANK, and TBK1 accumulate in cytoplasmic condensates after viral infection or 5'ppp-dsRNA stimulation; NAP1 condensates concentrate TBK1 and later PP2A. | (glon2025nap1switchesfrom pages 1-5, glon2025nap1switchesfrom pages 5-9) |
| Regulation by condensate formation | AZI2 can first activate and then limit TBK1 signaling through condensate dynamics. | NAP1 initially enhances TBK1 activity; subsequent TBK1-dependent phosphorylation favors NAP1 condensate formation that concentrates TBK1 with PP2A phosphatase, promoting TBK1 dephosphorylation and dampening IFN output. | (glon2025nap1switchesfrom pages 1-5, glon2025nap1switchesfrom pages 5-9) |
| Regulation by competing adaptors / cargo receptors | AZI2 function is tuned by competition with OPTN, NDP52, TANK, and SINTBAD for TBK1 or pathway assembly. | In mitophagy, NAP1/SINTBAD compete with OPTN for TBK1 but support NDP52-driven progression; in innate signaling, the homologous adaptors compete for TBK1 binding and create pathway-specific assemblies. | (adriaenssens2024controlofmitophagy pages 1-2, adriaenssens2024controlofmitophagy pages 2-3, zhou2020tbk1acentral pages 2-3) |
| Regulation by FIP200/RB1CC1 | RB1CC1/FIP200 restrains AZI2-TBK1 signaling in some settings but also physically interfaces with NAP1 in selective autophagy. | Structural and cancer studies show NAP1 binds FIP200/RB1CC1; loss of RB1CC1 causes AZI2 accumulation in puncta and TBK1 hyperactivation, indicating a regulatory brake on AZI2-TBK1 signaling. | (fu2021structuralandbiochemical pages 1-2, okamoto2020fip200suppressesimmune pages 1-3, yeo2024azi2mediatestbk1 pages 2-4) |
| Regulation by proteostasis | AZI2 abundance is controlled by TBK1-dependent phosphorylation and ubiquitin-proteasome degradation in mitosis. | Phosphoproteomic and cell-cycle studies identified NAP1 Ser318 as a TBK1-regulated site associated with mitotic degradation, supporting negative feedback on NAP1 levels during cell division. | (paul2023nakassociatedprotein1nap1 pages 1-2, paul2023nakassociatedprotein pages 9-12) |
Table: This table compiles the main experimentally supported functions of human AZI2/NAP1, emphasizing its role as a TBK1 adaptor across innate immune signaling, selective autophagy, TNF signaling, and mitosis. It also summarizes context-specific localization, structural features, and regulatory mechanisms with direct citations to the available evidence.
This report synthesizes recent, high-quality evidence on AZI2/NAP1, organizing its functional annotation in human with quantitative and mechanistic depth. For details, see embedded artifact and referenced literature.
References
(paul2023nakassociatedprotein1nap1 pages 1-2): Swagatika Paul, Shireen A. Sarraf, Ki Hong Nam, Leila Zavar, Nicole DeFoor, Sahitya Ranjan Biswas, Lauren E. Fritsch, Tomer M. Yaron, Jared L. Johnson, Emily M. Huntsman, Lewis C. Cantley, Alban Ordureau, and Alicia M. Pickrell. Nak-associated protein 1/nap1 activates tbk1 to ensure accurate mitosis and cytokinesis. The Journal of Cell Biology, Dec 2023. URL: https://doi.org/10.1083/jcb.202303082, doi:10.1083/jcb.202303082. This article has 9 citations.
(yeo2024azi2mediatestbk1 pages 1-2): Syn Kok Yeo, Michael Haas, Kanakaraju Manupati, Mingang Hao, Fuchun Yang, Song Chen, and Jun-Lin Guan. Azi2 mediates tbk1 activation at unresolved selective autophagy cargo receptor complexes with implications for cd8 t-cell infiltration in breast cancer. Autophagy, 20:525-540, Sep 2024. URL: https://doi.org/10.1080/15548627.2023.2259775, doi:10.1080/15548627.2023.2259775. This article has 9 citations and is from a domain leading peer-reviewed journal.
(ujevic2024tbk1associatedadapterstank pages 1-2): Andrea Ujevic, Daniela Knizkova, Alzbeta Synackova, Michaela Pribikova, Tijana Trivic, Anna Dalinskaya, Ales Drobek, Veronika Niederlova, Darina Paprckova, Roldan De Guia, Petr Kasparek, Jan Prochazka, Juraj Labaj, Olha Fedosieieva, Bernhard Florian Roeck, Ondrej Mihola, Zdenek Trachtulec, Radislav Sedlacek, Ondrej Stepanek, and Peter Draber. Tbk1-associated adapters tank and azi2 protect mice against tnf-induced cell death and severe autoinflammatory diseases. Nature Communications, Nov 2024. URL: https://doi.org/10.1038/s41467-024-54399-4, doi:10.1038/s41467-024-54399-4. This article has 7 citations and is from a highest quality peer-reviewed journal.
(fu2021structuralandbiochemical pages 1-2): Tao Fu, Mingfang Zhang, Zixuan Zhou, Ping Wu, Chao Peng, Yingli Wang, Xinyu Gong, Ying Li, Yaru Wang, Xiaolong Xu, Miao Li, Liqiang Shen, and Lifeng Pan. Structural and biochemical advances on the recruitment of the autophagy-initiating ulk and tbk1 complexes by autophagy receptor ndp52. Aug 2021. URL: https://doi.org/10.1126/sciadv.abi6582, doi:10.1126/sciadv.abi6582. This article has 53 citations and is from a highest quality peer-reviewed journal.
(glon2025nap1switchesfrom pages 1-5): Damien Glon, Quentin Riller, Frédéric Rivière, Benjamin Léonardon, Ariane Guillemot, Laïla Sago, Olivier Pellé, Duong Ho-Nhat, Karine Brochard, Brigitte Bader-Meunier, Marie-Louise Frémond, Alice Lepelley, Yanick Crow, Maud Tusseau, Alexandre Belot, Cécile Lagaudrière-Gesbert, Frédéric Rieux-Laucat, and Yves Gaudin. Nap1 switches from an activator to a limiter of interferon induction by trapping tbk1 in condensates. bioRxiv, May 2025. URL: https://doi.org/10.1101/2025.05.21.655319, doi:10.1101/2025.05.21.655319. This article has 0 citations.
(zhou2020tbk1acentral pages 2-3): Ruyuan Zhou, Qian Zhang, and Pinglong Xu. Tbk1, a central kinase in innate immune sensing of nucleic acids and beyond. Acta biochimica et biophysica Sinica, 52:757-767, May 2020. URL: https://doi.org/10.1093/abbs/gmaa051, doi:10.1093/abbs/gmaa051. This article has 105 citations and is from a peer-reviewed journal.
(yeo2024azi2mediatestbk1 pages 2-4): Syn Kok Yeo, Michael Haas, Kanakaraju Manupati, Mingang Hao, Fuchun Yang, Song Chen, and Jun-Lin Guan. Azi2 mediates tbk1 activation at unresolved selective autophagy cargo receptor complexes with implications for cd8 t-cell infiltration in breast cancer. Autophagy, 20:525-540, Sep 2024. URL: https://doi.org/10.1080/15548627.2023.2259775, doi:10.1080/15548627.2023.2259775. This article has 9 citations and is from a domain leading peer-reviewed journal.
(adriaenssens2024controlofmitophagy pages 1-2): Elias Adriaenssens, Thanh Ngọc Nguyen, Justyna Sawa-Makarska, Grace Khuu, Martina Schuschnig, Stephen Shoebridge, Emily Maria Watts, Kitti Dora Csalyi, Benjamin Scott Padman, Michael Lazarou, and Sascha Martens. Control of mitophagy initiation and progression by the tbk1 adaptors nap1 and sintbad. Feb 2024. URL: https://doi.org/10.5281/zenodo.10637352, doi:10.5281/zenodo.10637352. This article has 45 citations.
(adriaenssens2024controlofmitophagy pages 2-3): Elias Adriaenssens, Thanh Ngọc Nguyen, Justyna Sawa-Makarska, Grace Khuu, Martina Schuschnig, Stephen Shoebridge, Emily Maria Watts, Kitti Dora Csalyi, Benjamin Scott Padman, Michael Lazarou, and Sascha Martens. Control of mitophagy initiation and progression by the tbk1 adaptors nap1 and sintbad. Feb 2024. URL: https://doi.org/10.5281/zenodo.10637352, doi:10.5281/zenodo.10637352. This article has 45 citations.
(ujevic2024tbk1associatedadapterstank pages 2-3): Andrea Ujevic, Daniela Knizkova, Alzbeta Synackova, Michaela Pribikova, Tijana Trivic, Anna Dalinskaya, Ales Drobek, Veronika Niederlova, Darina Paprckova, Roldan De Guia, Petr Kasparek, Jan Prochazka, Juraj Labaj, Olha Fedosieieva, Bernhard Florian Roeck, Ondrej Mihola, Zdenek Trachtulec, Radislav Sedlacek, Ondrej Stepanek, and Peter Draber. Tbk1-associated adapters tank and azi2 protect mice against tnf-induced cell death and severe autoinflammatory diseases. Nature Communications, Nov 2024. URL: https://doi.org/10.1038/s41467-024-54399-4, doi:10.1038/s41467-024-54399-4. This article has 7 citations and is from a highest quality peer-reviewed journal.
(glon2025nap1switchesfrom pages 5-9): Damien Glon, Quentin Riller, Frédéric Rivière, Benjamin Léonardon, Ariane Guillemot, Laïla Sago, Olivier Pellé, Duong Ho-Nhat, Karine Brochard, Brigitte Bader-Meunier, Marie-Louise Frémond, Alice Lepelley, Yanick Crow, Maud Tusseau, Alexandre Belot, Cécile Lagaudrière-Gesbert, Frédéric Rieux-Laucat, and Yves Gaudin. Nap1 switches from an activator to a limiter of interferon induction by trapping tbk1 in condensates. bioRxiv, May 2025. URL: https://doi.org/10.1101/2025.05.21.655319, doi:10.1101/2025.05.21.655319. This article has 0 citations.
(adriaenssens2024controlofmitophagy pages 3-4): Elias Adriaenssens, Thanh Ngọc Nguyen, Justyna Sawa-Makarska, Grace Khuu, Martina Schuschnig, Stephen Shoebridge, Emily Maria Watts, Kitti Dora Csalyi, Benjamin Scott Padman, Michael Lazarou, and Sascha Martens. Control of mitophagy initiation and progression by the tbk1 adaptors nap1 and sintbad. Feb 2024. URL: https://doi.org/10.5281/zenodo.10637352, doi:10.5281/zenodo.10637352. This article has 45 citations.
(paul2023nakassociatedprotein pages 9-12): Swagatika Paul, Shireen A. Sarraf, Ki Hong Nam, Leila Zavar, Sahitya Ranjan Biswas, Lauren E. Fritsch, Nicole DeFoor, Tomer M. Yaron, Jared L. Johnson, Emily M. Huntsman, Lewis C. Cantley, Alban Ordureau, and Alicia M. Pickrell. Nak associated protein 1/nap1 is required for mitosis and cytokinesis by activating tbk1. bioRxiv, Jan 2023. URL: https://doi.org/10.1101/2022.03.09.483647, doi:10.1101/2022.03.09.483647. This article has 0 citations.
(zhou2020tbk1acentral pages 1-2): Ruyuan Zhou, Qian Zhang, and Pinglong Xu. Tbk1, a central kinase in innate immune sensing of nucleic acids and beyond. Acta biochimica et biophysica Sinica, 52:757-767, May 2020. URL: https://doi.org/10.1093/abbs/gmaa051, doi:10.1093/abbs/gmaa051. This article has 105 citations and is from a peer-reviewed journal.
(paul2023nakassociatedprotein1nap1 pages 2-5): Swagatika Paul, Shireen A. Sarraf, Ki Hong Nam, Leila Zavar, Nicole DeFoor, Sahitya Ranjan Biswas, Lauren E. Fritsch, Tomer M. Yaron, Jared L. Johnson, Emily M. Huntsman, Lewis C. Cantley, Alban Ordureau, and Alicia M. Pickrell. Nak-associated protein 1/nap1 activates tbk1 to ensure accurate mitosis and cytokinesis. The Journal of Cell Biology, Dec 2023. URL: https://doi.org/10.1083/jcb.202303082, doi:10.1083/jcb.202303082. This article has 9 citations.
(song2024ptpn23dependentescrtmachinery pages 1-2): Dongyan Song, Yuxin Cen, Zhe Qian, Xiaoli S. Wu, Keith Rivera, Tse-Luen Wee, Osama E. Demerdash, Kenneth Chang, Darryl Pappin, Christopher R. Vakoc, and Nicholas K. Tonks. Ptpn23-dependent escrt machinery functions as a cell death checkpoint. Nature Communications, Nov 2024. URL: https://doi.org/10.1038/s41467-024-54749-2, doi:10.1038/s41467-024-54749-2. This article has 6 citations and is from a highest quality peer-reviewed journal.
(okamoto2020fip200suppressesimmune pages 1-3): Takako Okamoto, Syn Kok Yeo, Mingang Hao, Mary Rose Copley, Michael A. Haas, Song Chen, and Jun-Lin Guan. Fip200 suppresses immune checkpoint therapy responses in breast cancers by limiting azi2/tbk1/irf signaling independent of its canonical autophagy function. Cancer Research, 80:3580-3592, Sep 2020. URL: https://doi.org/10.1158/0008-5472.can-20-0519, doi:10.1158/0008-5472.can-20-0519. This article has 35 citations and is from a highest quality peer-reviewed journal.
UniProt: Q9H6S1. Gene: AZI2 (5-azacytidine-induced protein 2); synonyms NAP1 (NAK-associated
protein 1), TBKBP2, TILP. 392 aa. Two coiled-coil regions (40-76, 102-196), a homodimerization
region (1-197), and a TBK1/IKKε-binding region (216-257; the "TBD" Pfam PF12845 TBK1-binding
domain). Cytoplasmic. Subject to K48-linked polyubiquitination by TRIM38 (by similarity, mouse).
PMID:14560022 — This is the foundational identification. NAP1 binds TBK1 (NAK) and IKBKE
(IKKε), activates TBK1, facilitates its oligomerization, and the NAK-NAP1 complex phosphorylates
Ser536 of p65/RELA. NAP1 enhances NF-κB-dependent reporter activation; depletion reduces it.
PMID:14560022.
UniProt FUNCTION: "Adapter protein which binds TBK1 and IKBKE playing a role in antiviral innate
immunity. Activates serine/threonine-protein kinase TBK1 and facilitates its oligomerization.
Enhances the phosphorylation of NF-kappa-B p65 subunit RELA by TBK1."
[PMID:17142768 (Sasai et al., abstract-only in cache) "NAK-associated protein 1 participates in
both the TLR3 and the cytoplasmic pathways in type I IFN induction"] — NAP1 is a shared adaptor
downstream of TLR3 (via TICAM1/TRIF) and the cytoplasmic RIG-I/MDA5 pathway feeding IRF3
activation and type I IFN (IFN-β). This paper is the ComplexPortal source for the NAS annotations:
defense response to virus (GO:0051607), type I IFN-mediated signaling (GO:0060337), and
serine/threonine protein kinase complex (GO:1902554, the TBK1/IKKε-NAP1 complex CPX-6038).
NAP1 also participates in IFN-β promoter activation via TICAM1/TRIF (UniProt FUNCTION,
PubMed:15611223 — not in cache, abstract elsewhere). PMID:21931631 confirms NAP1 in the TBK1 interactome and functional network.
PMID:30459273 — Crystal structures (5Z7G, 5Z7L) of NAP1 33-75 bound to the SKICH domains of the
autophagy receptors NDP52 (CALCOCO2) and TAX1BP1 (TAXBP1). NAP1 (and its paralog SINTBAD) bridge
these cargo receptors to TBK1, recruiting/activating TBK1 at autophagic cargo. This places NAP1 in
the selective-autophagy axis as a TBK1-recruiting adaptor.
GO:0043124 (negative regulation of canonical NF-κB signaling), IEA via Ensembl Compara from mouse
ortholog Q9QYP6 (ECO:0000265, GO_REF:0000107). This is interesting because the human characterization
(PMID:14560022) shows NAP1 potentiates NF-κB. The mouse-derived "negative regulation" may reflect a
context-specific role. Keep as non-core given the dominant positive/adaptor role and the
ortholog-transfer basis; do not remove an Ensembl orthology-based annotation without contradicting
evidence (the human paper shows positive regulation, which is a different assay context).
*-deep-research*.md file found in this gene directory.involved_in xenophagy over-reaches; GO:1904415 regulation of xenophagy (verified real) or leaving it as the TBK1-adaptor capture is more defensible than the bare process projection.xenophagy (GO:0098792, involved_in) to regulation of xenophagy (GO:1904415) — AZI2 is a TBK1-recruiting adaptor, not a cargo receptor. [YAML] optionally add GO:1904415 regulation of xenophagy (involved_in) supported by PMID:30459273 to reflect the NDP52/TAX1BP1-TBK1 bridging role; do not add bare GO:0098792.ALP|Autophagy substrate selection|Autophagy receptor regulation|Xenophagy (1 row) ; PN-node mapping: Xenophagy type → mapped/ok_for_propagation_to_go GO:0098792 xenophagy (goa_status=new_to_goa); all ancestors (group/class/branch) = no_mapping.involved_in xenophagy over-reaches; GO:1904415 regulation of xenophagy (verified real) or leaving it as the TBK1-adaptor capture is more defensible than the bare process projection.xenophagy for this member.xenophagy (GO:0098792, involved_in) to regulation of xenophagy (GO:1904415) — AZI2 is a TBK1-recruiting adaptor, not a cargo receptor. [YAML] optionally add GO:1904415 regulation of xenophagy (involved_in) supported by PMID:30459273 to reflect the NDP52/TAX1BP1-TBK1 bridging role; do not add bare GO:0098792.This file is generated from the current PROTEOSTASIS phase-1 dossier and local gene-review artifacts. Edit the source review, PN mapping, or dossier rather than this generated note when correcting the underlying curation.
id: Q9H6S1
gene_symbol: AZI2
product_type: PROTEIN
status: COMPLETE
taxon:
id: NCBITaxon:9606
label: Homo sapiens
description: >-
AZI2 (5-azacytidine-induced protein 2), better known as NAP1 (NAK-associated
protein 1; also TBKBP2, TILP), is a cytoplasmic adapter protein that binds and
positively regulates the IkappaB kinase (IKK)-related serine/threonine kinases
TBK1 (NAK) and IKBKE (IKKepsilon). The protein has an N-terminal
homodimerization region and two coiled-coil segments, and a C-terminal
TBK1/IKBKE-binding domain (the Pfam TBD module, residues ~216-257) shared with
the related adapters TANK and TBKBP1/SINTBAD. By binding TBK1, NAP1 promotes
TBK1 activation and oligomerization and thereby couples upstream innate-immune
signals to TBK1 kinase output. NAP1 functions as a shared adaptor in type I
interferon induction downstream of both the endosomal Toll-like receptor 3
(via the TRIF/TICAM1 adaptor) and the cytoplasmic RIG-I/MDA5 RNA-sensing
pathway, driving IRF3 activation and IFN-beta production, and it also
potentiates NF-kappaB activation, including TBK1-dependent phosphorylation of
the p65/RELA subunit. NAP1 is a constituent of the TBK1-IKKepsilon-NAP1
complex. Structurally, its N-terminal region binds the SKICH domains of the
selective-autophagy cargo receptors NDP52/CALCOCO2 and TAX1BP1, allowing NAP1
(with its paralog SINTBAD) to bridge these receptors to TBK1 and recruit/
activate TBK1 at autophagic cargo. NAP1 is itself a phosphoprotein and is
subject to TRIM38-mediated K48-linked polyubiquitination and degradation.
alternative_products:
- name: 1 (Long)
id: Q9H6S1-1
- name: 2 (Short)
id: Q9H6S1-3
sequence_note: VSP_023817, VSP_023818
- name: '3'
id: Q9H6S1-4
sequence_note: VSP_047087, VSP_047090
- name: '4'
id: Q9H6S1-5
sequence_note: VSP_047088, VSP_047089
existing_annotations:
- term:
id: GO:0005737
label: cytoplasm
evidence_type: IBA
original_reference_id: GO_REF:0000033
qualifier: is_active_in
review:
summary: Phylogenetic (PAN-GO) inference that NAP1 is active in the cytoplasm, consistent with experimental localization and its cytoplasmic adaptor role for TBK1/IKBKE.
action: ACCEPT
reason: Correct core compartment; NAP1 acts as a cytoplasmic adaptor that binds and activates TBK1, consistent with the experimental cytoplasmic localization (PMID:14560022).
supported_by:
- reference_id: file:human/AZI2/AZI2-uniprot.txt
supporting_text: 'SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:14560022}.'
- term:
id: GO:0005737
label: cytoplasm
evidence_type: IEA
original_reference_id: GO_REF:0000120
qualifier: located_in
review:
summary: Electronic transfer of cytoplasmic localization (UniProt subcellular location / mouse ortholog), redundant with but consistent with the experimental and IBA cytoplasm annotations.
action: ACCEPT
reason: Correct core cytoplasmic localization; redundant electronic assignment that agrees with the EXP (PMID:14560022) and IBA evidence.
supported_by:
- reference_id: file:human/AZI2/AZI2-uniprot.txt
supporting_text: 'SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:14560022}.'
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:14743216
qualifier: enables
review:
summary: IntAct interaction with TBK1 (Q9UHD2) from a TNF-alpha/NF-kappaB pathway interaction map. Records the functionally central TBK1 interaction but bare protein binding is uninformative.
action: KEEP_AS_NON_CORE
reason: Captures the key NAP1-TBK1 interaction underlying its adaptor function, but bare protein binding (GO:0005515) is uninformative per curation guidelines; the functional MF/CC is better captured by the kinase-complex and IFN annotations.
supported_by:
- reference_id: file:human/AZI2/AZI2-uniprot.txt
supporting_text: 'Q9H6S1; Q9UHD2: TBK1; NbExp=7; IntAct=EBI-359973, EBI-356402;'
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:21903422
qualifier: enables
review:
summary: IntAct interaction with TBK1 (Q9UHD2) from a dynamic innate-immunity (type I IFN) interaction network. Bare protein binding is uninformative.
action: KEEP_AS_NON_CORE
reason: Records the real NAP1-TBK1 interaction in the type I IFN network but bare protein binding is uninformative.
supported_by:
- reference_id: file:human/AZI2/AZI2-uniprot.txt
supporting_text: 'Q9H6S1; Q9UHD2: TBK1; NbExp=7; IntAct=EBI-359973, EBI-356402;'
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:21931555
qualifier: enables
review:
summary: IntAct interactions from the vaccinia virus C6 study (NAP1 binds vaccinia C6/OPG029 and TBK1). C6 is a viral antagonist that targets TBK1 adaptors to block IRF3/IRF7. Bare protein binding is uninformative.
action: KEEP_AS_NON_CORE
reason: Records a real host-virus interaction (vaccinia C6 targeting NAP1 as a TBK1 adaptor) and the TBK1 interaction, but bare protein binding is uninformative.
supported_by:
- reference_id: file:human/AZI2/AZI2-uniprot.txt
supporting_text: 'Q9H6S1; P17362: OPG029; Xeno; NbExp=2; IntAct=EBI-359973, EBI-9519257;'
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:22014111
qualifier: enables
review:
summary: IntAct interaction with a flavivirus protein (Q9E7P0) from a flavivirus NS3/NS5 yeast two-hybrid screen. Bare protein binding is uninformative.
action: KEEP_AS_NON_CORE
reason: High-throughput host-virus Y2H interaction; bare protein binding is uninformative and the interaction is not central to the core function.
supported_by:
- reference_id: file:human/AZI2/AZI2-uniprot.txt
supporting_text: 'Q9H6S1; Q9E7P0; Xeno; NbExp=2; IntAct=EBI-359973, EBI-11361108;'
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:29251827
qualifier: enables
review:
summary: IntAct interaction with TBK1 (Q9UHD2) from the TBK1/STING/MDA5 interactome (TTC4 study). Bare protein binding is uninformative.
action: KEEP_AS_NON_CORE
reason: Records the NAP1-TBK1 interaction in the antiviral innate-immune interactome but bare protein binding is uninformative.
supported_by:
- reference_id: file:human/AZI2/AZI2-uniprot.txt
supporting_text: 'Q9H6S1; Q9UHD2: TBK1; NbExp=7; IntAct=EBI-359973, EBI-356402;'
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:32707033
qualifier: enables
review:
summary: IntAct interaction with TBK1 (Q9UHD2) from a human kinase interaction network. Bare protein binding is uninformative.
action: KEEP_AS_NON_CORE
reason: Records the NAP1-TBK1 interaction but bare protein binding is uninformative.
supported_by:
- reference_id: file:human/AZI2/AZI2-uniprot.txt
supporting_text: 'Q9H6S1; Q9UHD2: TBK1; NbExp=7; IntAct=EBI-359973, EBI-356402;'
- term:
id: GO:0043124
label: negative regulation of canonical NF-kappaB signal transduction
evidence_type: IEA
original_reference_id: GO_REF:0000107
qualifier: involved_in
review:
summary: Ensembl Compara transfer from the mouse ortholog (Q9QYP6) of a negative regulation of canonical NF-kappaB role. The human-characterized role of NAP1 is predominantly to potentiate NF-kappaB (PMID:14560022), so this orthology-based term is at best context-specific and conflicts with the dominant positive-regulatory role.
action: KEEP_AS_NON_CORE
reason: Orthology-transferred (mouse) annotation; not contradicted by clearly identified human evidence so retained, but the dominant, experimentally characterized human role is positive regulation/potentiation of NF-kappaB, so this negative-regulation term is non-core and possibly context-specific.
supported_by:
- reference_id: file:human/AZI2/AZI2-uniprot.txt
supporting_text: Promotes TBK1-induced as well as TNF or PMA-induced activation of NF-kappa-B
- term:
id: GO:0005737
label: cytoplasm
evidence_type: EXP
original_reference_id: PMID:14560022
qualifier: located_in
review:
summary: Experimental evidence that NAP1 localizes to the cytoplasm (foundational identification paper). Core localization where NAP1 binds and activates TBK1/IKBKE.
action: ACCEPT
reason: Experimentally supported core cytoplasmic localization, the compartment in which NAP1 acts as a TBK1/IKBKE adaptor.
supported_by:
- reference_id: file:human/AZI2/AZI2-uniprot.txt
supporting_text: 'SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:14560022}.'
- term:
id: GO:0051607
label: defense response to virus
evidence_type: NAS
original_reference_id: PMID:17142768
qualifier: involved_in
review:
summary: ComplexPortal author-statement (TBK1-IKKepsilon-NAP1 complex, CPX-6038) that NAP1 participates in antiviral defense. NAP1 acts as a shared adaptor downstream of TLR3 and the cytoplasmic RIG-I/MDA5 pathway in type I IFN induction.
action: ACCEPT
reason: Core biological process; NAP1 is an established adaptor in antiviral innate immunity feeding IRF3 activation and IFN-beta induction via both TLR3/TRIF and the cytoplasmic RNA-sensing pathways. Recent literature compiled in the falcon deep-research report reinforces NAP1 as a positive regulator of the TBK1-IRF3/IRF7 type I IFN axis downstream of the major nucleic-acid sensing pathways, although the specific sensor branches (RLR-MAVS, cGAS-STING, TLR3-TRIF) are general TBK1-pathway context rather than uniquely AZI2-specific findings.
supported_by:
- reference_id: file:human/AZI2/AZI2-uniprot.txt
supporting_text: Adapter protein which binds TBK1 and IKBKE playing a role in antiviral innate immunity
- reference_id: PMID:17142768
supporting_text: NAK-associated protein 1 participates in both the TLR3 and the cytoplasmic pathways in type I IFN induction
- reference_id: file:human/AZI2/AZI2-deep-research-falcon.md
supporting_text: NAP1 is critical for linking TBK1 to IRF3/IRF7 and the type I interferon response, acting downstream of RLR–MAVS, cGAS–STING, and TLR3–TRIF pathways.
- term:
id: GO:0060337
label: type I interferon-mediated signaling pathway
evidence_type: NAS
original_reference_id: PMID:17142768
qualifier: involved_in
review:
summary: ComplexPortal author-statement that NAP1 (in the TBK1-IKKepsilon-NAP1 complex) participates in type I interferon signaling/induction. NAP1 couples TLR3 and cytoplasmic RNA sensing to IRF3/type I IFN.
action: KEEP_AS_NON_CORE
reason: NAP1's documented role is in type I IFN induction (driving IRF3 activation and IFN-beta production upstream), rather than in the downstream IFN-receptor (JAK/STAT) signaling that GO:0060337 (type I interferon-mediated signaling pathway) most precisely denotes; retained as a correct but imprecise pathway-context annotation. The defense-response-to-virus and IFN-beta-production-related roles are the core capture.
supported_by:
- reference_id: PMID:17142768
supporting_text: NAK-associated protein 1 participates in both the TLR3 and the cytoplasmic pathways in type I IFN induction
- term:
id: GO:1902554
label: serine/threonine protein kinase complex
evidence_type: NAS
original_reference_id: PMID:17142768
qualifier: part_of
review:
summary: ComplexPortal author-statement that NAP1 is part of a serine/threonine protein kinase complex (the TBK1-IKKepsilon-NAP1 complex, CPX-6038). Core cellular component capturing NAP1's defining role as a subunit of the TBK1/IKBKE kinase complex.
action: ACCEPT
reason: Core cellular component; NAP1 is a constituent/regulatory subunit of the TBK1-IKKepsilon kinase complex, which is the structural basis of its adaptor and kinase-activating function. The falcon deep-research report corroborates the mechanistic basis, with NAP1 binding promoting TBK1 activation via Ser172 autophosphorylation.
supported_by:
- reference_id: file:human/AZI2/AZI2-uniprot.txt
supporting_text: Activates serine/threonine-protein kinase TBK1 and facilitates its oligomerization
- reference_id: file:human/AZI2/AZI2-deep-research-falcon.md
supporting_text: It binds and activates TANK-binding kinase 1 (TBK1), inducing conformational changes that enable TBK1 autophosphorylation at Ser172—essential for kinase activation
core_functions:
- description: Acts as an adapter and positive regulator of the IKK-related serine/threonine kinases TBK1 and IKBKE, binding them via its C-terminal TBK1-binding domain to promote TBK1 activation and oligomerization as a subunit of the TBK1-IKKepsilon-NAP1 kinase complex.
supported_by:
- reference_id: file:human/AZI2/AZI2-uniprot.txt
supporting_text: Adapter protein which binds TBK1 and IKBKE playing a role in antiviral innate immunity. Activates serine/threonine-protein kinase TBK1 and facilitates its oligomerization.
- reference_id: PMID:14560022
supporting_text: NAP1 activates NAK and facilitates its oligomerization
locations:
- id: GO:0005737
label: cytoplasm
- description: Functions as a shared adaptor in innate antiviral immunity, coupling TLR3 (via TRIF/TICAM1) and the cytoplasmic RIG-I/MDA5 RNA-sensing pathway to TBK1-driven IRF3 activation and type I interferon (IFN-beta) induction, and potentiating NF-kappaB activation including TBK1-dependent phosphorylation of p65/RELA.
supported_by:
- reference_id: PMID:17142768
supporting_text: NAK-associated protein 1 participates in both the TLR3 and the cytoplasmic pathways in type I IFN induction
- reference_id: PMID:14560022
supporting_text: the NAK-NAP1 complex itself effectively phosphorylated serine 536 of the p65/RelA subunit of NF-kappaB
directly_involved_in:
- id: GO:0051607
label: defense response to virus
references:
- id: file:human/AZI2/AZI2-deep-research-falcon.md
title: Falcon deep research report for AZI2
findings:
- statement: AZI2/NAP1 is a scaffold/adaptor (not an enzyme) that binds TBK1 and promotes its activation via adaptor-driven assembly/oligomerization and TBK1 Ser172 autophosphorylation, linking TBK1 to multiple signaling platforms and cargo-receptor complexes (innate immunity, selective autophagy/mitophagy, TNF signaling, mitosis).
reference_section_type: OTHER
reference_review:
relevance: HIGH
correctness: UNVERIFIED
review_notes: >-
LLM-synthesized deep-research report; treat as a lead, not as primary
evidence. AZI2-SPECIFIC claims it surfaces (anchored to retrievable primary
papers not in the current GOA) include: NAP1/AZI2 is required for TBK1
activation at centrosomes during mitosis/cytokinesis, with TBK1
phosphorylating NAP1 at Ser318 to trigger its degradation (Paul et al.
2023, J Cell Biol, doi:10.1083/jcb.202303082); AZI2 mediates TBK1 activation
at unresolved selective-autophagy cargo-receptor complexes upon RB1CC1/FIP200
loss, driving IRF3 chemokine signaling and CD8 T-cell infiltration in breast
cancer (Yeo et al. 2024, Autophagy, doi:10.1080/15548627.2023.2259775;
Okamoto et al. 2020, Cancer Res); AZI2/NAP1 with SINTBAD controls mitophagy
initiation/progression by tuning TBK1 recruitment to OPTN/NDP52
(Adriaenssens et al. 2024); AZI2 and TANK cooperatively recruit TBK1 to the
TNF receptor to restrain RIPK1-driven cell death (Ujevic et al. 2024, Nat
Commun, doi:10.1038/s41467-024-54399-4). GENERAL TBK1-PATHWAY / ADAPTOR-FAMILY
inference (TBK1 as the central kinase downstream of RLR-MAVS, cGAS-STING,
TLR3-TRIF; competition among NAP1/TANK/SINTBAD for TBK1) is shared
pathway/family context, not necessarily AZI2-specific. The Glon et al. 2025
condensate model is a non-peer-reviewed bioRxiv preprint and is treated as
speculative. None of these primary papers are cited in the current GOA, so
no existing-annotation action was changed on the basis of this report alone;
it is recorded to flag candidate functions (mitosis/cytokinesis, selective
autophagy/mitophagy, TNF-receptor cell-death checkpoint) for future curation.
- id: GO_REF:0000033
title: Annotation inferences using phylogenetic trees
findings: []
- id: GO_REF:0000107
title: Automatic transfer of experimentally verified manual GO annotation data to
orthologs using Ensembl Compara
findings: []
- id: GO_REF:0000120
title: Combined Automated Annotation using Multiple IEA Methods
findings: []
- id: PMID:14560022
title: Identification of NAP1, a regulatory subunit of IkappaB kinase-related kinases
that potentiates NF-kappaB signaling.
findings:
- statement: NAP1 interacts with the IKK-related kinases NAK/TBK1 and IKBKE/IKKepsilon, activates TBK1 and facilitates its oligomerization, and the NAK-NAP1 complex phosphorylates Ser536 of p65/RELA; NAP1 potentiates NF-kappaB-dependent gene expression and localizes to the cytoplasm.
reference_section_type: ABSTRACT
reference_review:
relevance: HIGH
correctness: VERIFIED
review_notes: Full text available. Foundational identification of NAP1 as a TBK1/IKBKE adaptor and activator; source of the core adaptor function and cytoplasmic localization (EXP).
- id: PMID:14743216
title: A physical and functional map of the human TNF-alpha/NF-kappa B signal transduction
pathway.
findings: []
reference_review:
relevance: MEDIUM
correctness: VERIFIED
review_notes: Pathway-scale interaction map; source of an IntAct NAP1-TBK1 protein binding annotation.
- id: PMID:17142768
title: NAK-associated protein 1 participates in both the TLR3 and the cytoplasmic
pathways in type I IFN induction.
findings:
- statement: NAP1 acts as a shared adaptor downstream of TLR3 (via TRIF/TICAM1) and the cytoplasmic RIG-I/MDA5 dsRNA-sensing pathway to drive IRF3 activation and type I interferon induction.
reference_section_type: ABSTRACT
reference_review:
relevance: HIGH
correctness: VERIFIED
review_notes: Abstract-only in cache (full_text_available false). Source of the ComplexPortal NAS annotations (defense response to virus, type I IFN signaling, ser/thr kinase complex) for the TBK1-IKKepsilon-NAP1 complex.
- id: PMID:21903422
title: Mapping a dynamic innate immunity protein interaction network regulating
type I interferon production.
findings: []
reference_review:
relevance: MEDIUM
correctness: VERIFIED
review_notes: Innate-immunity interaction network; source of an IntAct NAP1-TBK1 protein binding annotation.
- id: PMID:21931555
title: Vaccinia virus protein C6 is a virulence factor that binds TBK-1 adaptor
proteins and inhibits activation of IRF3 and IRF7.
findings:
- statement: Vaccinia virus C6 binds the TBK1 adaptor proteins (NAP1, TANK, SINTBAD) and inhibits IRF3/IRF7 activation, identifying NAP1 as a TBK1 adaptor targeted by a viral immune antagonist.
reference_section_type: ABSTRACT
reference_review:
relevance: MEDIUM
correctness: VERIFIED
review_notes: Full text available. Source of host-virus IntAct protein binding annotations (vaccinia C6, TBK1); corroborates NAP1 as a bona fide TBK1 adaptor in antiviral signaling.
- id: PMID:22014111
title: 'Flavivirus NS3 and NS5 proteins interaction network: a high-throughput yeast
two-hybrid screen.'
findings: []
reference_review:
relevance: LOW
correctness: VERIFIED
review_notes: High-throughput host-virus Y2H screen; source of a bare protein binding annotation with a flavivirus protein.
- id: PMID:29251827
title: Quantitative Proteomics Identified TTC4 as a TBK1 Interactor and a Positive
Regulator of SeV-Induced Innate Immunity.
findings: []
reference_review:
relevance: MEDIUM
correctness: VERIFIED
review_notes: TBK1/STING/MDA5 interactome study; source of an IntAct NAP1-TBK1 protein binding annotation.
- id: PMID:30459273
title: Mechanistic insights into the interactions of NAP1 with the SKICH domains
of NDP52 and TAX1BP1.
findings:
- statement: Crystal structures define how the N-terminal region of NAP1 binds the SKICH domains of the selective-autophagy cargo receptors NDP52/CALCOCO2 and TAX1BP1, allowing NAP1 to bridge these receptors to TBK1.
reference_section_type: ABSTRACT
reference_review:
relevance: HIGH
correctness: VERIFIED
review_notes: Full text available. Structural basis for NAP1 acting as a TBK1-recruiting adaptor for autophagy cargo receptors NDP52 and TAX1BP1.
- id: PMID:32707033
title: Kinase Interaction Network Expands Functional and Disease Roles of Human
Kinases.
findings: []
reference_review:
relevance: LOW
correctness: VERIFIED
review_notes: Kinase interaction network; source of an IntAct NAP1-TBK1 protein binding annotation.
suggested_questions:
- question: Does human NAP1 have a genuine negative-regulatory role in canonical NF-kappaB signaling (as inferred by orthology from mouse), or is the IEA GO:0043124 annotation context-specific given that the foundational human study shows NAP1 potentiates NF-kappaB?
- question: How is NAP1's adaptor activity partitioned between TBK1 activation in antiviral type I IFN induction and TBK1 recruitment to NDP52/TAX1BP1 in selective autophagy, and do its four isoforms (which differ in the TBK1-binding region) have distinct functions?
- question: Recent primary literature (compiled in the falcon deep-research report but not yet reflected in GOA) implicates AZI2/NAP1 in TBK1 activation at centrosomes during mitosis/cytokinesis (Paul et al. 2023), in selective autophagy/mitophagy via OPTN/NDP52 and FIP200/RB1CC1 (Adriaenssens et al. 2024; Yeo et al. 2024), and in a TBK1-dependent TNF-receptor cell-death checkpoint with TANK (Ujevic et al. 2024). Should these become curated GO annotations (e.g. mitotic cell cycle, macroautophagy/mitophagy, negative regulation of programmed cell death), and which are AZI2-specific versus shared TBK1-adaptor functions?
suggested_experiments:
- description: Reconstitute TBK1 activation in vitro with purified TBK1 and wild-type versus TBK1-binding-domain (residues 216-257) mutant NAP1 to quantify how NAP1 promotes TBK1 trans-autophosphorylation and oligomerization, and test substrate phosphorylation (IRF3, p65/RELA).
- description: Use NAP1 (AZI2) knockout cells reconstituted with isoform-specific or domain-mutant constructs to dissect NAP1's contribution to TLR3- versus RIG-I/MDA5-driven IFN-beta induction and to NDP52/TAX1BP1-dependent selective autophagy/xenophagy.