Affinage

GPN1

GPN-loop GTPase 1 · UniProt Q9HCN4

Length
374 aa
Mass
41.7 kDa
Annotated
2026-06-10
43 papers in source corpus 22 papers cited in narrative 22 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 8/8 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

GPN1 is an essential, GTP-dependent GPN-loop GTPase that functions as a cytoplasmic assembly chaperone and nuclear-import factor for RNA polymerase II (PMID:20855544, PMID:21768307). It belongs to the SIMIBI GTPase class and operates through a self-activating mechanism in which the conserved GPN loop of one protomer completes the catalytic site of its partner across a tight dimer interface (PMID:17468740); in human cells GPN1 forms an obligate heterodimer with GPN3 through internal helices, insertions, and the reciprocal GPN loops, and this interaction is required both for the steady-state stability of both GTPases and for their function in RNAPII targeting (PMID:25241168, PMID:31298811). Mechanistically, GPN1 toggles between GDP-bound closed and GTP-bound open conformations, the latter exposing a hydrophobic pocket that binds peptides from RNAPII subunit interfaces; peptide binding allosterically stimulates GTP hydrolysis, coupling chaperone activity to the nucleotide cycle and driving cytoplasmic assembly of the two largest RNAPII subunits RPB1 and RPB2 (PMID:26711263, PMID:35314265). GTP-loaded GPN1 binds assembled RNAPII (via RPB7/RPB4 and the CTD) and escorts it into the nucleus through an unconventional, importin-α/β-independent pathway, with the GPN loop and GTP-binding motifs strictly required for this import (PMID:21768307, PMID:21844196). After delivery, GPN1 returns to the cytoplasm using a Crm1-recognized nuclear export sequence and also governs the nucleocytoplasmic shuttling of the partner factor RPAP2 (PMID:22796641, PMID:23723243). A eukaryote-specific C-terminal tail, absent in archaeal homologs, stabilizes the GPN1 dimer and confers a genetically separable role in microtubule stability and mitotic progression independent of RNAPII assembly (PMID:27965115, PMID:28153773). GPN1 activity extends to other nuclear polymerases, as GTP-bound GPN1/GPN3 are required for RNA polymerase I localization to ribosomal DNA (PMID:33079728). An initially proposed role in XPA nuclear import (PMID:11058119) was subsequently not supported (PMID:23861882).

Mechanistic history

Synthesis pass · year-by-year structured walk · 19 steps
  1. 2000 Medium

    Established GPN1 as a bona fide cytoplasmic GTPase and linked it to a nuclear-import-relevant protein interface, framing it as a possible escort factor.

    Evidence Yeast two-hybrid screen against XPA, recombinant GTPase assay, and XPA deletion mutagenesis

    PMID:11058119

    Open questions at the time
    • XPA interaction later shown not to govern XPA nuclear import
    • no structural basis for GTPase activity at this stage
  2. 2003 Medium

    Showed GPN1 is a nucleocytoplasmic shuttling protein with an NES and a GTP-binding-dependent partner interaction, hinting at regulated transport functions.

    Evidence Yeast two-hybrid, reciprocal Co-IP, leptomycin B imaging, and reporter assays with MBD2

    PMID:12588985

    Open questions at the time
    • MBD2/transcriptional-repression role not integrated with later RNAPII model
    • NES not yet mapped to residues
  3. 2007 High

    Defined the catalytic mechanism by showing the GPN loop of one monomer completes the active site of its partner, establishing a self-activating dimeric GTPase.

    Evidence X-ray crystallography of archaeal homolog PAB0955

    PMID:17468740

    Open questions at the time
    • archaeal homodimer lacks the eukaryotic C-terminal tail
    • no substrate or cargo captured in structure
  4. 2010 High

    Identified the core biological function: GPN1 is required for nuclear import of RNAPII largest subunits, with the GPN loop and GTP motifs essential and microtubules involved.

    Evidence AP-MS, siRNA knockdown, fluorescence microscopy, and dominant-negative mutants in human cells

    PMID:20855544

    Open questions at the time
    • mechanism of import (importin-dependent vs not) unresolved at this point
    • role of microtubules not mechanistically defined
  5. 2011 High

    Demonstrated GTP-dependence of RNAPII binding and that import proceeds through an unconventional, importin-independent pathway, refining the transport model.

    Evidence Human Co-IP/fractionation with dominant-negative mutants and yeast Npa3 GTP-binding assays, ChIP, and degron depletion

    PMID:21768307 PMID:21844196

    Open questions at the time
    • import receptor/route still not molecularly identified
    • stoichiometry of GPN1 with RNAPII during import unknown
  6. 2012 Medium

    Mapped the Crm1-recognized NES and showed GPN1 controls the shuttling of the RNAPII biogenesis factor RPAP2, positioning GPN1 within a recycling transport circuit.

    Evidence Site-directed mutagenesis, leptomycin B imaging, and domain-mapping Co-IP of RPAP2

    PMID:22796641 PMID:23723243

    Open questions at the time
    • how GPN1 export coordinates with RNAPII delivery unresolved
    • RPAP2 functional consequence downstream unclear
  7. 2012 High

    Placed GPN proteins upstream of Iwr1 in RNAPII biogenesis and extended their requirement to RNAPIII but not RNAPI.

    Evidence Yeast temperature-sensitive alleles, genetic epistasis, and NLS-fusion suppression

    PMID:23267056

    Open questions at the time
    • precise step distinguishing GPN from Iwr1 function not defined
    • molecular basis for polymerase specificity unknown
  8. 2013 Medium

    Corrected the founding model by showing GPN1 is dispensable for XPA nuclear import, redirecting its biology firmly toward RNAPII assembly.

    Evidence siRNA knockdown, nuclear fractionation, and Co-IP measuring importin-dependent XPA import

    PMID:23861882

    Open questions at the time
    • negative result from a single lab
    • residual or context-specific XPA role not fully excluded
  9. 2014 Medium

    Established the GPN1-GPN3 heterodimer as an obligate unit whose interaction maintains the steady-state levels of both GTPases.

    Evidence Co-IP of endogenous proteins, imaging, and expression-level analysis

    PMID:25241168

    Open questions at the time
    • mechanism of mutual stabilization not defined here
    • functional division of labor between GPN1 and GPN3 unclear
  10. 2015 High

    Provided the chaperone-GTPase coupling mechanism: a GTP-induced open conformation exposes a hydrophobic pocket that binds RNAPII interface peptides and allosterically stimulates hydrolysis.

    Evidence Crystal structures of yeast Npa3 in two nucleotide states with chaperone, peptide-binding, and GTPase assays

    PMID:26711263

    Open questions at the time
    • structure with full RNAPII subunit not captured
    • how chaperone cycle drives directional nuclear import unresolved
  11. 2017 High

    Defined the eukaryote-specific C-terminal tail biochemically as a dimer-stabilizing element and confirmed human GPN1 GTPase activity in vitro.

    Evidence Recombinant protein purification with SEC, DLS, native PAGE, CD, and GTPase assays on wild-type and ΔC mutants

    PMID:28153773

    Open questions at the time
    • structure of the human heterodimer not determined
    • tail's regulatory inputs in vivo not addressed here
  12. 2017 Medium

    Revealed a regulatory role for GPN1 in partner stability by inhibiting nuclear K216 polyubiquitination of GPN3.

    Evidence MG132 treatment, K216R mutagenesis, Co-IP, and pulse-chase half-life assays

    PMID:29029378

    Open questions at the time
    • E3 ligase responsible for GPN3 ubiquitination unidentified
    • physiological trigger for nuclear GPN3 turnover unknown
  13. 2016 Medium

    Genetically separated GPN1's two functions, showing the C-terminal tail is dispensable for RNAPII targeting but required for microtubule stability and mitosis.

    Evidence Yeast C-terminal truncations, benomyl sensitivity, imaging, and BIK1 genetic interaction

    PMID:27965115

    Open questions at the time
    • molecular target of GPN1 in microtubule dynamics unknown
    • whether human GPN1 tail has the same role untested here
  14. 2019 Medium

    Mapped the human GPN1-GPN3 interface at residue resolution and showed it is required for the dominant-negative effect on RNAPII targeting, tying dimer integrity to function.

    Evidence FRET in live cells with W132D/M227D mutants and RNAPII localization assays

    PMID:31298811

    Open questions at the time
    • heterodimer crystal/cryo-EM structure not solved
    • how interface mutations affect GTPase cycle untested
  15. 2019 Low

    Implicated GPN1 in co-transport with the RPAP1 ortholog IYO, requiring GTP-bound GPN1 and the partner's NLS for nuclear delivery.

    Evidence Arabidopsis transient/stable expression, Co-IP, localization, and mutagenesis

    PMID:31552063

    Open questions at the time
    • evidence is from a plant ortholog and single Co-IP
    • whether mammalian import uses an RPAP1 NLS not directly shown
  16. 2020 Medium

    Embedded GPN1 in the cytoplasmic Rpb2 subcomplex assembly pathway alongside GPN3 and RPAP1/Rba50, with mutual protein-level dependency.

    Evidence Yeast multicopy suppressor screen, Co-IP, AID depletion, and cross-species validation in human cells

    PMID:32985767

    Open questions at the time
    • order of subunit addition during assembly not fully resolved
    • direct vs indirect Rba50 contacts not distinguished
  17. 2021 Medium

    Extended GPN1/GPN3 function to RNA polymerase I, showing GTP-bound GPN1/3 are required for Pol I localization to rDNA and are MYC-regulated.

    Evidence MYC overexpression, IMPDH inhibition to deplete GTP, and constitutively GTP-bound mutant rescue with Pol I localization readout

    PMID:33079728

    Open questions at the time
    • whether GPN1 acts directly on Pol I assembly vs localization unclear
    • mechanism distinguishing Pol I from Pol II handling unknown
  18. 2022 Medium

    Defined a reversible RNAPII assembly stress response in which loss of GPN-family function produces cytoplasmic RNAPII foci that resolve upon factor recovery.

    Evidence Yeast temperature-sensitive and AID degron mutants with foci imaging and assembly assays

    PMID:35314265

    Open questions at the time
    • composition and fate of cytoplasmic foci not fully characterized
    • signaling that senses assembly failure unidentified
  19. 2025 Medium

    Identified post-translational regulation of GPN1: O-fucosylation in Toxoplasma and C-terminal IDR phosphorylation in yeast that modulates function in a ribosome-biogenesis genetic context.

    Evidence Toxoplasma endogenous tagging with interactome proteomics; yeast Ser→Ala mutagenesis with translation-inhibitor sensitivity in bud27Δ

    PMID:40788873 PMID:40888172

    Open questions at the time
    • functional consequence of O-fucosylation minimal/unclear
    • kinase and physiological role of IDR phosphorylation in higher eukaryotes unknown

Open questions

Synthesis pass · forward-looking unresolved questions
  • How GPN1's GTPase/chaperone cycle is mechanically converted into directional, importin-independent nuclear translocation of fully assembled RNAPII remains unresolved.
  • no structure of GPN1/3 bound to intact RNAPII
  • molecular identity of the unconventional import route undefined
  • human in vivo C-terminal tail/microtubule role not directly demonstrated

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0003924 GTPase activity 5 GO:0140096 catalytic activity, acting on a protein 2 GO:0044183 protein folding chaperone 1
Localization
GO:0005829 cytosol 5 GO:0005634 nucleus 3
Pathway
R-HSA-9609507 Protein localization 5 R-HSA-74160 Gene expression (Transcription) 4 R-HSA-392499 Metabolism of proteins 2
Partners
GPN3MBD2RPAP1RPAP2RPB1RPB2RPB7
Complex memberships
GPN1-GPN3 heterodimer

Evidence

Reading pass · 22 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2000 GPN1 (XAB1) is a cytoplasmic GTPase that binds to the N-terminal region of XPA (nucleotide excision repair protein); purified recombinant XAB1 has intrinsic GTPase activity; deletion of XPA residues 30-34 (required for XPA nuclear localization) abolishes the XAB1-XPA interaction Yeast two-hybrid screening, purified recombinant protein GTPase assay, deletion mutagenesis Nucleic acids research Medium 11058119
2003 GPN1 (MBDin) localizes mainly in the cytoplasm but shuttles to the nucleus; its nuclear export is mediated by an NES; GPN1 interacts with MBD2 (requiring the C-terminal 46-aa region of MBD2 and an intact GTP-binding site of GPN1); GPN1 overexpression relieves MBD2-mediated transcriptional repression from methylated promoters without altering DNA methylation Yeast two-hybrid, co-immunoprecipitation, fluorescence imaging with leptomycin B treatment, transcriptional reporter assays, bisulfite analysis Molecular and cellular biology Medium 12588985
2007 Crystal structure of archaeal GPN-loop GTPase PAB0955 (Pyrococcus abyssi homolog of human XAB1/GPN1) reveals a homodimeric architecture; the conserved GPN loop is part of the catalytic site of the opposing monomer and stabilizes the phosphate ion, defining a novel self-activating GTPase mechanism in the SIMIBI class X-ray crystallography EMBO reports High 17468740
2010 GPN1 (RPAP4) shuttles between nucleus and cytoplasm and is required for nuclear import of RNAPII largest subunits RPB1 and RPB2; the GPN loop motif and GTP-binding motifs are essential for nuclear localization of RPB1; microtubule assembly is also required for this nuclear import process Affinity purification-mass spectrometry, siRNA knockdown, fluorescence microscopy, dominant-negative GTP-binding mutants Molecular & cellular proteomics High 20855544
2011 Human GPN1 and GPN3 stably associate with RNAPII from cytoplasmic and nuclear fractions; GPN1 and GPN3 directly interact with RNAPII subunit RPB7/RPB4 and the CTD of RNAPII; siRNA depletion of GPN1 or GPN3 causes decreased nuclear RNAPII and cytoplasmic accumulation; a dominant-negative GPN1 with mutations in the GTP-binding pocket retains RNAPII in a cytoplasmic complex, demonstrating GTP-dependent nuclear import Co-immunoprecipitation from cytoplasmic/nuclear fractions, siRNA knockdown, stable cell lines expressing dominant-negative mutants, fluorescence microscopy Molecular and cellular biology High 21768307
2011 Yeast Npa3 (GPN1 ortholog) is required for nuclear localization of RNAPII in vivo; Npa3-RNAPII binding is significantly increased by GTP or GTPγS; the GTP-binding mutant that cannot hydrolyze GTP binds RNAPII constitutively even without added GTP, while the mutant that cannot bind GTP fails to bind RNAPII; Npa3 does not interact detectably with importin α/β pathway components, indicating an unconventional nuclear import pathway Degron-mediated depletion, chromatin immunoprecipitation, in vitro GTP-binding assays, site-directed mutagenesis, co-immunoprecipitation The Journal of biological chemistry High 21844196
2012 A functional nuclear export sequence (NES) in human GPN1 spanning residues 292-304 (LERLRKDMGSVAL) is recognized by Crm1 and mediates cytoplasmic retention; V302A/L304A double mutation causes nuclear accumulation; this NES is sufficient to drive nuclear export of EYFP fusion protein Site-directed mutagenesis, leptomycin B treatment, fluorescence microscopy, molecular modeling Biochimica et biophysica acta Medium 22796641
2012 In S. cerevisiae, GPN1 (Npa3) functions upstream of Iwr1 in RNAPII biogenesis; GPN2 and GPN3 are also required for nuclear localization of both RNAPII and RNAPIII but not RNAPI; the nuclear import defect of iwr1Δ (but not gpn2/gpn3 mutants) is partially suppressed by an NLS fused to Rpb3, placing GPN proteins upstream of Iwr1 Temperature-sensitive alleles, genetic epistasis, NLS-fusion suppression, fluorescence microscopy of nuclear localization Genetics High 23267056
2013 GPN1 (RPAP4) silencing causes retention of RPAP2 in the nucleus; RPAP4/GPN1 binds to RPAP2 through RPAP2's C-terminal domain (amino acids 156-612), and this interaction is required for cytoplasmic export of RPAP2; GPN1 thus controls RPAP2 nucleocytoplasmic shuttling as part of RNAPII biogenesis siRNA silencing, domain-mapping co-immunoprecipitation, fluorescence microscopy with leptomycin B Nucleic acids research Medium 23723243
2013 XAB1 (GPN1) siRNA knockdown has no detectable effect on nuclear import of XPA in response to UV damage; importin-α4 (UV-dependent) and importin-α7 mediate XPA nuclear import instead, contradicting the originally proposed role of XAB1 in XPA import siRNA knockdown, nuclear fractionation, co-immunoprecipitation PloS one Medium 23861882
2014 Human GPN1 and GPN3 associate tightly as a complex (essentially all endogenous GPN1 and GPN3 co-immunoprecipitate); GPN1 retains GPN3 in the cytoplasm when coexpressed; the GPN1-GPN3 interaction is essential for maintaining steady-state protein levels of both GTPases Co-immunoprecipitation, fluorescence microscopy, leptomycin B treatment, expression level analysis FEBS letters Medium 25241168
2015 Crystal structure of S. cerevisiae Npa3 (GPN1 ortholog) trapped in GDP-bound closed and GTP-analog-bound open conformations; the open conformation exposes a conserved hydrophobic pocket distant from the active site; Npa3 has chaperone activity and interacts with hydrophobic peptides from RNAPII subunit interfaces; GTPase activity is allosterically stimulated by hydrophobic peptide binding, suggesting a chaperone-GTPase coupling mechanism for RNAPII assembly X-ray crystallography, in vitro chaperone assays, peptide-binding assays, GTPase activity measurements Molecular and cellular biology High 26711263
2016 The C-terminal tail of yeast Npa3/GPN1 (absent in archaeal GPN) is dispensable for RNAPII nuclear targeting and transcriptional activity but is required for microtubule stability, mitotic progression, and vacuole integrity; genetic interaction with BIK1 (microtubule plus-end tracking protein) places GPN1 C-terminal function in microtubule dynamics independent of RNAPII C-terminal truncation mutants, benomyl sensitivity assays, fluorescence microscopy, genetic interaction analysis Biochimica et biophysica acta. Molecular cell research Medium 27965115
2017 Human GPN1 forms a homodimer stabilized by its C-terminal tail; purified recombinant GPN1 binds GDP and non-hydrolyzable GTP analog GMPPCP and hydrolyzes GTP; C-terminal deletion mutant (GPN1ΔC) still dimerizes via the GTPase domain but the dimer spontaneously dissociates into monomers, showing the C-terminal tail stabilizes the dimer Recombinant protein purification, size-exclusion chromatography, dynamic light scattering, native PAGE, circular dichroism, in vitro GTPase activity assay Protein expression and purification High 28153773
2017 GPN1 inhibits polyubiquitination of GPN3 on K216 in a dose-dependent manner; GPN3 is polyubiquitinated on K216 (not K189) and degraded by the proteasome specifically in the cell nucleus; this identifies GPN1 as a regulator of GPN3 stability through inhibition of nuclear ubiquitination Proteasome inhibitor (MG132) treatment, site-directed mutagenesis (K216R), co-immunoprecipitation, pulse-chase half-life assay FEBS letters Medium 29029378
2019 Human GPN1 and GPN3 form a heterodimer through a large interface comprising internal α-helix 7, insertion 2, and the GPN-loop from each protein; FRET experiments confirm very close proximity in cytoplasm of live cells; W132D and M227D mutations in GPN1 disrupt GPN1-GPN3 interaction by FRET and also abolish the dominant-negative effect on RNAPII nuclear targeting, demonstrating that intact GPN1-GPN3 interaction is required for their cellular function FRET microscopy, molecular modeling, site-directed mutagenesis, RNAPII localization assay The FEBS journal Medium 31298811
2019 Plant RPAP1 ortholog IYO interacts with GPN GTPases including GPN1; this interaction requires an intact G1 motif (GTP-binding) in GPN1, indicating IYO binds the nucleotide-bound form of GPN1; IYO NLS deletion does not prevent GPN1 binding but blocks GPN1 nuclear import, suggesting IYO and GPN1 are co-transported as a complex using IYO's NLS Transient and stable plant expression assays, co-immunoprecipitation, subcellular localization microscopy, deletion and point mutagenesis Frontiers in plant science Low 31552063
2020 Yeast Npa3 (GPN1 ortholog) interacts with Gpn3 and assembly factor Rba50 (human RPAP1 analog); Rpb2 (second largest RNAPII subunit) interacts with both Npa3 and Rba50, placing them in Rpb2 subcomplex assembly; human GPN1 similarly interacts with GPN3 and RPAP1; mutual protein-level dependency exists between Npa3 and Gpn3 Multicopy suppressor genetic screen, co-immunoprecipitation, auxin-inducible degron (AID) protein degradation, cross-species validation FASEB journal Medium 32985767
2021 GPN1 and GPN3 are upregulated by MYC and direct RNA Polymerase I (Pol I) to ribosomal DNA; constitutively GTP-bound GPN1/3 mutants rescue Pol I ribosomal DNA localization after GTP depletion by IMPDH inhibition, demonstrating that GTP-bound GPN1/3 are required for Pol I localization to rDNA MYC overexpression, IMPDH inhibitor treatment, constitutively active GTP-bound mutant rescue experiments, ChIP or localization assays for Pol I at rDNA The Journal of clinical investigation Medium 33079728
2022 Npa3/GPN1 and Gpn3 directly participate in assembly of the two largest RNAPII subunits (Rpb1 and Rpb2) in the cytoplasm; Gpn3 deficiency disrupts RNAPII assembly and causes cytoplasmic foci of RNAPII subunits; recovery of the defective assembly factor reverses foci formation, establishing a reversible 'RNAPII assembly stress response' Temperature-sensitive mutants, auxin-inducible degron, fluorescence microscopy of cytoplasmic foci, RNAPII assembly assays International journal of biological macromolecules Medium 35314265
2025 In Toxoplasma gondii, GPN1 is substantially O-fucosylated; deletion of the SPY O-fucosyltransferase causes a modest 24% reduction in GPN1 protein level but does not affect GPN1's cytoplasmic localization or its association with RNAPII subunits in proteomic interactome analysis Endogenous epitope tagging, quantitative proteomics (interactome), super-resolution immunofluorescence microscopy, SPY knockout Glycobiology Medium 40888172
2025 The C-terminal disordered domain (IDR) of Npa3/GPN1 is phosphorylated at Ser304/Ser308/Ser313; non-phosphorylatable alanine substitutions at these residues in a bud27Δ background markedly increase sensitivity to translation inhibitors, demonstrating that CTD phosphorylation regulates Npa3 function in ribosome biogenesis context Site-directed mutagenesis (Ser→Ala), growth sensitivity assays, disorder prediction, yeast genetic interaction (bud27Δ background) The FEBS journal Medium 40788873

Source papers

Stage 0 corpus · 43 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2010 The protein interaction network of the human transcription machinery reveals a role for the conserved GTPase RPAP4/GPN1 and microtubule assembly in nuclear import and biogenesis of RNA polymerase II. Molecular & cellular proteomics : MCP 91 20855544
2006 Generation and immunogenicity of novel HIV/AIDS vaccine candidates targeting HIV-1 Env/Gag-Pol-Nef antigens of clade C. Vaccine 71 17224219
2006 C. elegans Kallmann syndrome protein KAL-1 interacts with syndecan and glypican to regulate neuronal cell migrations. Developmental biology 63 16677626
2021 Guanosine triphosphate links MYC-dependent metabolic and ribosome programs in small-cell lung cancer. The Journal of clinical investigation 62 33079728
2006 TACC3 mediates the association of MBD2 with histone acetyltransferases and relieves transcriptional repression of methylated promoters. Nucleic acids research 57 16410616
2011 Human GTPases associate with RNA polymerase II to mediate its nuclear import. Molecular and cellular biology 51 21768307
2000 A novel cytoplasmic GTPase XAB1 interacts with DNA repair protein XPA. Nucleic acids research 50 11058119
2013 Nuclear import of RNA polymerase II is coupled with nucleocytoplasmic shuttling of the RNA polymerase II-associated protein 2. Nucleic acids research 48 23723243
2007 Structural insights into a new homodimeric self-activated GTPase family. EMBO reports 48 17468740
2003 MBDin, a novel MBD2-interacting protein, relieves MBD2 repression potential and reactivates transcription from methylated promoters. Molecular and cellular biology 44 12588985
2012 Biogenesis of RNA polymerases II and III requires the conserved GPN small GTPases in Saccharomyces cerevisiae. Genetics 42 23267056
2011 GTP-dependent binding and nuclear transport of RNA polymerase II by Npa3 protein. The Journal of biological chemistry 40 21844196
2015 Structure of GPN-Loop GTPase Npa3 and Implications for RNA Polymerase II Assembly. Molecular and cellular biology 32 26711263
2013 UV-induced nuclear import of XPA is mediated by importin-α4 in an ATR-dependent manner. PloS one 25 23861882
2012 Discovery of cell compartment specific protein-protein interactions using affinity purification combined with tandem mass spectrometry. Journal of proteome research 24 23157168
2012 A nuclear export sequence in GPN-loop GTPase 1, an essential protein for nuclear targeting of RNA polymerase II, is necessary and sufficient for nuclear export. Biochimica et biophysica acta 22 22796641
2016 Npa3/ScGpn1 carboxy-terminal tail is dispensable for cell viability and RNA polymerase II nuclear targeting but critical for microtubule stability and function. Biochimica et biophysica acta. Molecular cell research 17 27965115
2020 Npa3 interacts with Gpn3 and assembly factor Rba50 for RNA polymerase II biogenesis. FASEB journal : official publication of the Federation of American Societies for Experimental Biology 15 32985767
2014 Gpn1 and Gpn3 associate tightly and their protein levels are mutually dependent in mammalian cells. FEBS letters 12 25241168
2019 FRET-based analysis and molecular modeling of the human GPN-loop GTPases 1 and 3 heterodimer unveils a dominant-negative protein complex. The FEBS journal 10 31298811
2019 Identification of Domains and Factors Involved in MINIYO Nuclear Import. Frontiers in plant science 10 31552063
2012 Deficiency in nucleotide excision repair family gene activity, especially ERCC3, is associated with non-pigmented hair fiber growth. PloS one 10 22615732
2013 Regulation of TGFβ superfamily signaling by two separable domains of glypican LON-2 in C. elegans. Worm 9 24778932
2023 Evidence for involvement of the alcohol consumption WDPCP gene in lipid metabolism, and liver cirrhosis. Scientific reports 7 37996473
2025 Genome-wide transcriptomic response of whole blood to radiation. Scientific reports 6 40473848
2022 Npa3-Gpn3 cooperate to assemble RNA polymerase II and prevent clump of its subunits in the cytoplasm. International journal of biological macromolecules 6 35314265
2022 Synthetic negative genome screen of the GPN-loop GTPase NPA3 in Saccharomyces cerevisiae. Current genetics 5 35660944
2017 The Gpn3 Q279* cancer-associated mutant inhibits Gpn1 nuclear export and is deficient in RNA polymerase II nuclear targeting. FEBS letters 5 28940195
2015 Abnormal expression of RNA polymerase II-associated proteins in muscle of patients with myofibrillar myopathies. Histopathology 4 25891782
2024 Assessing the causal relationship between plasma proteins and osteoporosis: novel insights into pathological mechanisms and therapeutic implications. Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA 3 39120624
2021 GPN-1/glypican and UNC-52/perlecan do not appear to function in BMP signaling to pattern the C. elegans postembryonic mesoderm. microPublication biology 3 34405137
2017 Human Gpn1 purified from bacteria binds guanine nucleotides and hydrolyzes GTP as a protein dimer stabilized by its C-terminal tail. Protein expression and purification 3 28153773
2017 Gpn3 is polyubiquitinated on lysine 216 and degraded by the proteasome in the cell nucleus in a Gpn1-inhibitable manner. FEBS letters 2 29029378
2002 The mei3 region of the Schizosaccharomyces pombe genome. Yeast (Chichester, England) 1 11921100
2026 Reversible cytoplasmic foci of RNA polymerase II subunits serve as proteostatic hubs orchestrating transcriptional reprogramming. International journal of biological macromolecules 0 41500282
2026 Unravelling genetic susceptibility and causal factors in liver health using MRI quantification of inflammation, fat and iron in the liver. Human genomics 0 41761370
2026 Identification of novel candidate neural genes for diet-induced obesity in outbred heterogeneous stock rats. Research square 0 42239780
2026 Integrative multi-omics analysis-based Mendelian randomization identifies association of DNA repair-related genes with oral cancer. Cancer biomarkers : section A of Disease markers 0 42257465
2025 Comprehensive analysis of GPN1 in human cancer and its effects on the migration of hepatocellular carcinoma cells. Biomolecules & biomedicine 0 39524004
2025 Characterization of the carboxy-terminal domain of the GPN-loop GTPase Npa3 reveals an intrinsically disordered region and phosphorylation-dependent regulation in the absence of BUD27. The FEBS journal 0 40788873
2025 O-fucosylation affects abundance but not localization of select nucleocytoplasmic proteins in toxoplasma gondii. Glycobiology 0 40888172
2025 Proposal of Chemical Inhibitors That Compete with the Binding of RNA Polymerase II Subunits to Essential GTPases GPN Npa3 and Gpn1. ACS omega 0 41244487
2025 A set of downregulated pleiotropic genes are possible multi-omics biomarkers underlying the irritable bowel syndrome-non-alcoholic fatty liver disease comorbidity. American journal of translational research 0 41552323

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