Affinage

CYTH2

Cytohesin-2 · UniProt Q99418

Length
400 aa
Mass
46.5 kDa
Annotated
2026-04-28
76 papers in source corpus 51 papers cited in narrative 50 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

CYTH2 (ARNO/cytohesin-2) is a guanine nucleotide exchange factor (GEF) for ARF-family GTPases that integrates lipid, receptor, and scaffolding signals to control membrane trafficking, actin remodeling, cell migration, and protein secretion. Its Sec7 domain catalyzes GDP-to-GTP exchange on ARF1 and ARF6 through a conserved 'glutamic finger' (Glu156) mechanism that displaces Mg²⁺ and GDP (PMID:9649435), while membrane recruitment is cooperatively driven by PH-domain binding to PIP3/PIP2, a polybasic C-terminal region regulated by PKC phosphorylation at Ser392 (PMID:10531036), and upstream activators including ARL4D, Gαq, V-ATPase a-subunit isoforms, and Arf6-GTP itself in a positive-feedback loop (PMID:21118813, PMID:17804820, PMID:16415858). At the plasma membrane and endosomes, CYTH2-activated ARF6 signals through Rac1 (via Dock180/ELMO), PLD, and the WAVE regulatory complex to drive lamellipodia formation, endocytosis, receptor trafficking, Schwann cell myelination, and inflammatory vascular permeability; full knockout in mice causes perinatal lethality with loss of Golgi integrity and global protein secretion that is rescued even by GEF-inactive CYTH2, revealing an essential ARF-GEF-independent structural role (PMID:41672711, PMID:23143332, PMID:25824033, PMID:16213822).

Mechanistic history

Synthesis pass · year-by-year structured walk · 17 steps
  1. 1997 High

    Establishing that ARNO is a direct ARF1 GEF whose membrane recruitment through PH-domain–PIP2 interaction is essential for catalytic function answered the foundational question of how cytosolic ARF exchange factors reach their substrates.

    Evidence In vitro nucleotide exchange assay on phospholipid vesicles with domain deletion mutants

    PMID:9268368

    Open questions at the time
    • Relative in vivo substrate preference (ARF1 vs ARF6) not resolved
    • Regulation beyond PIP2 binding unknown
  2. 1998 High

    Crystal structures of the Sec7 domain and identification of the Glu156 'glutamic finger' mechanism revealed how ARNO destabilizes Mg²⁺ and GDP from ARF, providing the first atomic-level understanding of ARF-GEF catalysis.

    Evidence X-ray crystallography at 2.0–2.2 Å resolution, site-directed mutagenesis (E156K/E156D) with in vitro exchange assays

    PMID:9476900 PMID:9510256 PMID:9649435

    Open questions at the time
    • Full Sec7–ARF complex structure not yet solved at the time
    • Mechanism of membrane-dependent enhancement not structurally resolved
  3. 1998 High

    Localization of ARNO to the plasma membrane (not Golgi) and demonstration of ARF6 activation and actin cytoskeletal remodeling established the primary cellular site of action and linked ARNO to cell morphology control.

    Evidence Subcellular fractionation, immunolocalization, and overexpression of domain mutants in HeLa cells with actin phenotyping

    PMID:9417041 PMID:9550703 PMID:9802902

    Open questions at the time
    • Whether ARNO also functions at intracellular compartments in vivo unclear
    • Downstream effectors of ARF6 for actin remodeling not identified
  4. 1999 High

    Discovery that PKC phosphorylation of Ser392 in the polybasic C-terminal region creates an electrostatic switch reducing membrane binding established a key regulatory mechanism controlling ARNO membrane association.

    Evidence In vitro phosphorylation, liposome cosedimentation, phosphomimetic mutants, in vivo membrane fractionation

    PMID:10531036 PMID:10801341

    Open questions at the time
    • Physiological context triggering PKC-mediated release not defined
    • Whether Ser392 phosphorylation is dynamically reversed in vivo unclear
  5. 2001 High

    Demonstration that ARNO activates endogenous ARF6 to independently stimulate Rac1 and PLD in epithelial cells resolved the downstream branching logic through which ARNO drives cell migration.

    Evidence Dominant-active ARNO expression in MDCK cells with ARF6-GTP, Rac-GTP, and PLD activity pulldown assays plus motility readout

    PMID:11481345

    Open questions at the time
    • Rac GEF identity downstream of ARF6 not yet determined
    • How PLD activity converges on motility mechanistically unknown
  6. 2001 High

    The finding that V-ATPase-dependent endosomal acidification recruits ARNO and ARF6 to early endosomes revealed a pH-sensing mechanism linking endosomal maturation to ARF signaling.

    Evidence Subcellular fractionation and in vitro translocation assay with ATP-driven acidification in kidney proximal tubule cells

    PMID:11278939

    Open questions at the time
    • Molecular identity of the V-ATPase subunit mediating ARNO interaction not yet mapped
    • Whether pH sensing is direct or indirect unclear
  7. 2005 High

    Identification of the Dock180/ELMO complex as the Rac GEF downstream of ARNO-ARF6 completed the signaling cascade from ARNO to Rac1 activation and cell motility.

    Evidence Dominant-negative Dock180 and ELMO mutants block ARNO-induced Rac-GTP and motility in MDCK cells

    PMID:16213822

    Open questions at the time
    • How ARF6-GTP recruits/activates Dock180–ELMO mechanistically unresolved
    • Contribution of other Rac GEFs in different cell types not excluded
  8. 2006 High

    Mapping the V-ATPase a2-subunit as the direct ARNO-binding partner on endosomes and showing that disruption of a2–ARNO interaction blocks endocytosis established a specific molecular link between V-ATPase and ARF-GEF signaling.

    Evidence Reciprocal co-immunoprecipitation, acidification-dependent binding, endocytosis assays in epithelial cells

    PMID:16415858

    Open questions at the time
    • Structural basis of pH-dependent interaction not resolved
    • Contribution of other a-subunit isoforms unknown at this point
  9. 2007 High

    Discovery that ARL4D and Gαq each recruit ARNO to the plasma membrane through distinct domain interactions (PH/polybasic for ARL4D; coiled-coil for Gαq) revealed multiple upstream activation inputs converging on ARNO.

    Evidence Yeast two-hybrid, co-immunoprecipitation, ARF6-GTP pulldowns, siRNA epistasis in multiple cell lines

    PMID:16650966 PMID:17804820 PMID:17846866

    Open questions at the time
    • Whether ARL4D and Gαq pathways are synergistic or context-specific not tested
    • Structural basis of Gαq–coiled-coil interaction not solved
  10. 2009 High

    Defining how scaffolds GRASP/IPCEF1 and paxillin coordinate ARNO coiled-coil and polybasic domains with Dock180 explained how multiprotein assemblies at leading edges enable efficient ARF-to-Rac signaling during migration.

    Evidence Coiled-coil deletion mutants, siRNA knockdown of GRASP/IPCEF1/paxillin, Rac-GTP pulldown, migration assays

    PMID:20016009 PMID:20525696

    Open questions at the time
    • Stoichiometry of the multiprotein complex not determined
    • Whether scaffolding varies across cell types unknown
  11. 2010 High

    Reconstitution showing that Arf6-GTP activates ARNO through its PH domain in a positive-feedback loop on membranes revealed a bistable switch mechanism that amplifies ARF signaling.

    Evidence In vitro GEF assay on liposomes with full-length membrane-bound Arf and PH domain point mutants

    PMID:21118813

    Open questions at the time
    • How the positive feedback is terminated in cells not addressed
    • Quantitative parameters of bistability not modeled
  12. 2012 High

    Demonstration that IL-1β signals through MYD88–ARNO–ARF6 to increase endothelial permeability independently of NF-κB, with SecinH3 providing in vivo vascular protection, established ARNO as a druggable node in inflammatory barrier dysfunction.

    Evidence Direct binding assay, siRNA, SecinH3 pharmacology, endothelial permeability assay, in vivo inflammatory models

    PMID:23143332

    Open questions at the time
    • Structural basis of MYD88–ARNO interaction not solved
    • Therapeutic window and off-target effects of SecinH3 in vivo not fully characterized
  13. 2013 High

    NMR-based mapping of the V-ATPase a2N peptide interaction with the ARNO Sec7 domain, competing with ARF switch 2, provided the structural mechanism for pH-dependent regulation of ARNO catalytic activity.

    Evidence NMR spectroscopy, in vitro GEF reconstitution, competition assays with recombinant proteins

    PMID:20153292 PMID:23288846

    Open questions at the time
    • Full-length a2–ARNO complex structure not available
    • How luminal pH change is transduced to cytoplasmic a2N conformation not resolved
  14. 2015 High

    Conditional knockout of CYTH2 in Schwann cells reduced ARF6 activity and myelin thickness, establishing an essential in vivo role for CYTH2 in peripheral nerve myelination.

    Evidence Schwann cell-specific conditional KO mice, ARF6-GTP assay, electron microscopy of sciatic nerve

    PMID:25824033

    Open questions at the time
    • Whether CYTH2 acts through ARF6 alone or also ARF1 in myelination not resolved
    • Downstream effectors of ARF6 in myelin wrapping unknown
  15. 2018 High

    The finding that INAVA's CUPID domain binds ARNO to promote F-actin assembly independently of GEF activity established a GEF-independent scaffolding function for ARNO in epithelial barrier maintenance and inflammatory signaling.

    Evidence Co-immunoprecipitation, domain binding, siRNA, actin dynamics and ubiquitination assays in epithelial cells and macrophages

    PMID:30355448

    Open questions at the time
    • Structural basis of CUPID–ARNO interaction not determined
    • Relative contribution of GEF-dependent vs -independent functions at the barrier unclear
  16. 2022 High

    Identification of Tyr381 as a phosphorylation switch regulated by PTP4A1 (dephosphorylation) and SH2B1 (protection), with knockin Y381F mice showing reduced myelination, revealed a tyrosine phosphorylation layer controlling ARNO activity in vivo.

    Evidence Y381F knockin mice, Schwann cell-specific conditional KO of PTP4A1/SH2B1, ARF6-GTP assay, electron microscopy

    PMID:35077201

    Open questions at the time
    • Kinase responsible for Tyr381 phosphorylation not identified
    • Whether Tyr381 regulation operates in non-Schwann cell contexts unknown
  17. 2026 High

    Full CYTH2 knockout causing perinatal lethality with Golgi volume loss and secretion failure—rescuable by GEF-inactive CYTH2—revealed an essential, ARF-GEF-independent structural role in Golgi maintenance and organismal viability.

    Evidence Global KO mice, organellar and secretome mass spectrometry, immunofluorescence, rescue with catalytically dead ARNO

    PMID:41672711

    Open questions at the time
    • Molecular mechanism of GEF-independent Golgi maintenance unknown
    • Which CYTH2 domain mediates Golgi structural role not mapped
    • Whether other cytohesin family members partially compensate in vivo not fully resolved

Open questions

Synthesis pass · forward-looking unresolved questions
  • The molecular mechanism by which CYTH2 maintains Golgi integrity independently of ARF-GEF activity, the structural basis for several key protein interactions (MYD88, INAVA-CUPID, Gαq), and the kinase responsible for Tyr381 phosphorylation remain unresolved.
  • GEF-independent Golgi maintenance mechanism uncharacterized
  • High-resolution structures of ARNO with MYD88, INAVA, or Gαq not available
  • Tyr381 kinase identity unknown
  • Whether positive-feedback bistability operates in vivo and how it is terminated not demonstrated

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098772 molecular function regulator activity 5 GO:0003924 GTPase activity 4 GO:0008289 lipid binding 3 GO:0060090 molecular adaptor activity 2
Localization
GO:0005886 plasma membrane 6 GO:0005768 endosome 3 GO:0005829 cytosol 2 GO:0005794 Golgi apparatus 1
Pathway
R-HSA-162582 Signal Transduction 5 R-HSA-5653656 Vesicle-mediated transport 4 R-HSA-1500931 Cell-Cell communication 2 R-HSA-168256 Immune System 2 R-HSA-9609507 Protein localization 2 R-HSA-392499 Metabolism of proteins 1
Partners
ARF1ARF6ARL4DGNAQIPCEF1MYD88PXNRLIP76
Complex memberships
ARNO–Dock180/ELMO migration complexV-ATPase–ARNO–ARF6 endosomal complex

Evidence

Reading pass · 50 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1997 ARNO (CYTH2) catalyzes guanine nucleotide exchange on ARF1 via its central Sec7 domain; the PH domain binds PIP2 to recruit ARNO to membranes, which dramatically enhances ARF1 activation. PIP2-PH interaction does not directly regulate catalytic activity but serves membrane recruitment. A stable complex between the Sec7 domain and nucleotide-free ARF1 can be isolated. In vitro nucleotide exchange assay with phospholipid vesicles, protein-lipid binding, domain deletion mutants The Journal of biological chemistry High 9268368
1998 Crystal structure of the Sec7 domain of human ARNO resolved at 2.0–2.2 Å; the domain is an elongated all-helical protein with a hydrophobic groove and adjacent conserved loop that constitute the ARF1-binding surface, interacting with the switch 1 and switch 2 regions of ARF1. X-ray crystallography, structure-based mutagenesis, protein footprinting Nature / Cell High 9476900 9510256
1998 Glu156 of the ARNO Sec7 domain acts as a 'glutamic finger' that destabilizes Mg2+ and GDP from ARF1 to drive nucleotide exchange; E156D and E156K mutations reduce exchange activity by orders of magnitude. E156K forms a complex with Mg2+-free ARF1-GDP without inducing GDP release. Switch I hydrophobic residues of ARF1 insert into the Sec7 groove; Lys73 of ARF1 switch II forms an ion pair with Asp183 of ARNO. Site-directed mutagenesis, in vitro nucleotide exchange assay, stable complex isolation The EMBO journal High 9649435
1998 ARNO localizes to the plasma membrane (not Golgi) in mammalian cells and stimulates nucleotide exchange on both ARF1 and ARF6 in vitro, with ARF6 being the likely in vivo target at the plasma membrane. In vitro GEF assay, subcellular fractionation, immunolocalization The Journal of biological chemistry High 9417041
1998 ARNO-induced actin stress fiber disassembly and ARF6-dependent actin rearrangement requires the PH domain for membrane localization; PKC phosphorylates ARNO at a site C-terminal to the PH domain but mutation of this site does not block actin rearrangement. Overexpression in HeLa cells, PKC agonist treatment, domain deletion mutants, immunofluorescence Molecular biology of the cell High 9802902
1998 Insulin stimulates PI3K-dependent translocation of ARNO from cytoplasm to plasma membrane in adipocytes via PH domain binding to PIP3; this translocation is blocked by wortmannin, LY294002, or dominant-negative p85. GFP-tagged ARNO live imaging in 3T3-L1 adipocytes, PI3K inhibitors, dominant-negative constructs, in vitro lipid binding Current biology High 9550703
1998 ARNO overexpression in HeLa cells inhibits the early secretory pathway, blocks ER-to-Golgi trafficking of SEAP, and causes disassembly of the Golgi complex, consistent with ARNO acting as an exchange factor for ARF1 in Golgi-to-ER transport. Overexpression in HeLa cells, SEAP secretion assay, endoglycosidase H resistance, immunofluorescence, cell fractionation Journal of cell science Medium 9788883
1999 PKC phosphorylates ARNO at Ser392 within the polybasic C-terminal domain; this introduces a negative charge that reduces ARNO membrane binding in vitro and in vivo and inhibits ARF exchange activity via a 'PH domain electrostatic switch' mechanism. In vitro phosphorylation, liposome binding assay, in vivo membrane fractionation, exchange activity assay, phosphomimetic mutants Current biology High 10531036
2000 The ARNO PH domain provides specific PIP3 > PIP2 binding; the adjacent polybasic C-domain adds nonspecific ionic interactions with acidic lipids (PS); PKC phosphorylation of Ser392 in the C-domain reduces ionic affinity for PS without affecting phosphoinositide specificity. Liposome cosedimentation, ionic strength titration, in vitro GEF activity assay with domain constructs Biochemistry High 10801341
2001 ARNO activates endogenous ARF6 (but not ARF1) at the plasma membrane in MDCK epithelial cells, leading to downstream Rac1 activation (required for motility) and phospholipase D (PLD) activation (required for motility via a separate pathway). Rac activation and PLD activation are independent downstream branches of ARF6. Dominant-active ARNO expression, ARF6-GTP pulldown assay, Rac-GTP pulldown, PLD activity assay, motility assay, dominant-negative constructs The Journal of cell biology High 11481345
2001 ARNO and ARF6 are recruited from cytosol to early endosomes in kidney proximal tubule cells in a V-ATPase-dependent, intra-endosomal acidification-dependent manner; this recruitment is reversed by V-ATPase inhibitors and pH uncouplers. Subcellular fractionation, immunolocalization, in vitro translocation assay with ATP-driven acidification, Western blot The Journal of biological chemistry High 11278939
2001 The Sec7 domains of ARNO and EFA6 determine their GEF selectivity: ARNO preferentially activates ARF1 on membranes whereas EFA6 exclusively activates ARF6; selectivity maps to the Sec7 domain and ARF core domains without the N-terminal myristoylated helix. In vitro GEF assay on phospholipid membranes, domain-swap experiments The Journal of biological chemistry High 11342560
2002 The N-terminal coiled-coil domain of ARNO/cytohesin-2 interacts with the scaffolding protein CASP; CASP is recruited to membrane ruffles by cytohesin in EGF-stimulated cells, revealing a functional interaction. Yeast two-hybrid screening, in vitro binding, co-immunoprecipitation in COS-1 cells, immunofluorescence The Journal of biological chemistry Medium 12052827
2003 ARNO and ARF6 regulate axonal elongation and branching in hippocampal neurons; downstream of ARF6, PI(4)P 5-kinase α mediates these effects on neurite extension. Catalytically inactive ARNO or dominant-negative ARF6 enhance extension; co-expression of constitutively active ARF6 abrogates this. Inactive ARNO/ARF6 also depletes Mena from growth cone leading edge. Overexpression of dominant-negative/constitutively active mutants in cultured rat hippocampal neurons, immunofluorescence, morphometric analysis Molecular biology of the cell High 14565977
2003 IPCEF1 interacts with the coiled-coil domain of cytohesin-2/ARNO and increases cytohesin-2-stimulated ARF-GTP formation both in vitro and in vivo; IPCEF1 is co-transported to the plasma membrane by cytohesin-2 upon EGF stimulation. Yeast two-hybrid, GST pulldown, immunoprecipitation, in vitro and in vivo ARF-GTP assay, immunofluorescence The Journal of biological chemistry Medium 12920129
2003 ARNO mediates insulin-stimulated ARF activation and PLD activation; both the PH domain (membrane targeting) and the Sec7 domain (catalytic activity) are required; coiled-coil domain deletion partially impairs membrane translocation. Transient transfection in HIRcB cells, domain deletion/mutation analysis, ARF-GTP pulldown, PLD activity assay, membrane fractionation BMC cell biology Medium 12969509
2004 An RNA aptamer specific for ARNO/cytohesin-2 (binding its N-terminal coiled-coil/Sec7 region) inhibits serum-response element-driven transcription and MAPK activation in vivo without inhibiting GEF activity in vitro, revealing a GEF-independent function of cytohesin-2's N-terminus in MAPK/SRE signaling. SELEX aptamer selection, intracellular aptamer (intramer) transfection, SRE-reporter assay, ERK phosphorylation assay PNAS Medium 15277685
2005 ARNO/cytohesin-2 directly binds the juxtamembrane carboxyl terminus of the A2A adenosine receptor; this interaction is required for ARF6-dependent sustained ERK/MAP kinase activation but not for cAMP signaling or receptor desensitization. Yeast two-hybrid, mutual pulldown of bacterial fusion proteins, co-immunoprecipitation, inducible dominant-negative expression, cAMP and ERK assays The Journal of biological chemistry High 16027149
2005 ARNO-dependent Rac1 activation in migrating MDCK cells is mediated by the bipartite Rac GEF Dock180/Elmo complex; catalytically inactive Dock180 or Elmo mutant that fails to couple to Dock180 both block ARNO-induced Rac activation and motility. β-PIX, another Rac GEF, is not required. Dominant-negative mutant overexpression, Rac-GTP pulldown, motility assay, co-localization by confocal microscopy Current biology High 16213822
2006 V-ATPase a2-isoform on early endosomes interacts with ARNO in an intra-endosomal acidification-dependent manner; ARF6 interacts with the c-subunit of V-ATPase. Disruption of the a2-ARNO interaction reversibly inhibits endocytosis; V-ATPase recruits ARNO and ARF6 to regulate the endocytic degradative pathway. Co-immunoprecipitation, acidification-dependent binding assay, inhibitor treatments, endocytosis assays Nature cell biology High 16415858
2006 ARNO is localized exclusively at the apical plasma membrane of polarized epithelial cells through its N-terminal coiled-coil domain; ARNO promotes apical endocytosis of the polymeric IgA receptor synergistically with ARF6, and coiled-coil domain deletion mislocalizes ARNO to both membrane surfaces and abolishes apical endocytosis stimulation. Overexpression of deletion mutants, immunofluorescence in polarized MDCK cells, endocytosis assay, dominant-negative ARF6 epistasis The Journal of biological chemistry Medium 16484220
2006 Gαq signaling leads to ARF6 activation through direct interaction with ARNO; activated Gαq forms molecular complexes preferentially with ARNO and ARF6, and direct binding between purified Gαq and ARNO is demonstrated. ARNO and ARF6 promote TPβ receptor internalization. Co-immunoprecipitation, in vitro binding with purified proteins, ARF6-GTP assay, receptor internalization assay Cellular signalling Medium 16650966
2007 ARL4D (a GTP-dependent plasma membrane GTPase) interacts with the PH and polybasic C-terminal domains of cytohesin-2/ARNO in a GTP-dependent manner, recruits ARNO to the plasma membrane, activates ARF6, and promotes actin stress fiber disassembly; inactive cytohesin-2 or siRNA knockdown of ARNO blocks ARL4D-induced effects. Yeast two-hybrid, co-IP, ARF6-GTP pulldown, siRNA knockdown, immunofluorescence, dominant-active/inactive mutants Molecular biology of the cell High 17804820
2007 CaSR stimulation triggers plasma membrane ruffling via a β-arrestin 1–ARNO–ARF6–ELMO pathway; β-arrestin 1 co-immunoprecipitates with both CaSR and ARNO at rest, and agonist treatment causes their co-translocation to membrane protrusions. Co-immunoprecipitation, siRNA knockdown, dominant-negative mutants, immunofluorescence Journal of cell science Medium 17623778
2007 The coiled-coil domain of cytohesin-2/ARNO interacts directly with Gαq; Gαq-Q209L (constitutively active) strongly promotes cytohesin plasma membrane localization; coiled-coil deletion mutants of cytohesin-1 and -2 cannot relay Gαq-mediated ARF6 activation. Co-immunoprecipitation in HEK293 cells, confocal immunofluorescence, deletion mutants Molecular and cellular biochemistry Medium 17846866
2009 The coiled-coil domain of ARNO is required for ARNO-induced cell motility and ARF-dependent Rac1 activation; scaffold proteins GRASP/Tamalin and IPCEF1 (binding the coiled-coil) coordinate the association of ARNO with Dock180 to enable ARF-to-Rac signaling. Coiled-coil deletion mutants, siRNA knockdown of GRASP and IPCEF1, Rac-GTP pulldown, migration assay, co-immunoprecipitation Molecular biology of the cell High 20016009
2010 Cytohesin-2/ARNO interacts with the focal adhesion adaptor paxillin via its LIM2 domain and the ARNO polybasic region; this complex localizes to leading edges of migrating 3T3-L1 preadipocytes and is required for cytohesin-2-mediated ARF6-dependent cell migration. Co-immunoprecipitation, pulldown with domain mutants, siRNA knockdown, SecinH3 inhibition, ARF6-GTP pulldown, migration assay The Journal of biological chemistry High 20525696
2010 On membranes, Arf6-GTP activates ARNO at nanomolar concentrations via the PH domain in a positive feedback loop; ARNO is further activated by its own product Arf1-GTP (another positive feedback); PH domain mutations that abolish Arf6-GTP interaction completely inactivate ARNO on liposomes but not in solution. In vitro GEF assay on liposomes with full-length membrane-bound Arf, PH domain point mutants, competition with Arf effectors The Journal of biological chemistry High 21118813
2010 Multiple sites on the N-terminus of the V-ATPase a2-subunit (a2N) interact with the Sec7, PH, and polybasic domains of ARNO; the a2N(1–17) peptide inhibits ARNO GEF activity by binding the Sec7 domain with KD ~344 nM; Ser392 phosphorylation abolishes a2N binding to the ARNO polybasic region. Synthetic peptide binding assays, SPR kinetics, pulldown with recombinant proteins, NMR structure determination, in silico docking, GEF activity assay Biochimica et biophysica acta High 20153292
2011 ARNO directly interacts with aldolase (but not other glycolytic enzymes) via the ARNO PH domain; SPR reveals KD = 2.84 × 10⁻¹⁰ M. Aldolase associates with early endosomal membranes and forms a complex with ARNO/Arf6 and V-ATPase. Aldolase knockdown causes cell morphology changes and acidic vesicle redistribution. GST pulldown, SPR, cell fractionation, siRNA knockdown, immunofluorescence American journal of physiology. Cell physiology Medium 21307348
2011 ARNO mediates glucose-stimulated insulin secretion in β-cells through sequential activation of ARF6 → Cdc42 → Rac1; siRNA knockdown of ARNO or inactive ARNO (E156K) reduces GSIS; co-immunoprecipitation shows increased ARNO–ARF6 association upon glucose stimulation. siRNA knockdown, dominant-negative mutants, SecinH3 inhibition, GST-GGA3/PAK-1 pulldown assays for ARF6/Rac GTP-loading, co-immunoprecipitation, insulin secretion assay Biochemical pharmacology Medium 21276423
2012 IL-1β signals through MYD88–ARNO–ARF6 to disrupt endothelial barrier function independently of NF-κB; ARNO binds directly to the adaptor MYD88; SecinH3 (ARNO inhibitor) enhances vascular stability in inflammatory arthritis and acute inflammation models in vivo. Direct binding assay (ARNO–MYD88), siRNA knockdown, SecinH3 inhibition, endothelial permeability assay, in vivo inflammatory models Nature High 23143332
2012 Salmonella recruits ARNO via ARF6 and SopB-induced PIP3 generation; ARNO in turn activates the WAVE regulatory complex (WRC) for actin polymerization and macropinosome formation; RNAi screening identified ARNO as key host ARF-GEF for Salmonella invasion. siRNA screen, immunofluorescence, invasion assay, dominant-negative ARF/ARNO mutants, phosphoinositide imaging Cell host & microbe Medium 22341462
2013 The N-terminal cytosolic tail of the V-ATPase a2-subunit (a2N(1–17)) directly inhibits cytohesin-2 GEF activity by interacting with its Sec7 domain; NMR determined that Phe5, Met10, Gln14 of a2N are involved; a2N competes with the switch 2 region of Arf1/Arf6 for Sec7 binding. This signaling is conserved across all four a-subunit isoforms and with yeast V-ATPase. In vitro GEF assay, NMR spectroscopy, in silico docking, binding/competition assays with recombinant proteins The Journal of biological chemistry High 23288846
2014 Cytohesin-2 interacts with CCDC120 in neurites of differentiating N1E-115 cells; CCDC120-containing vesicles transport cytohesin-2 anterogradely along neurites; CCDC120 knockdown reduces Arf6 activation and inhibits neurite growth; CCDC120 lacking the cytohesin-2-binding CC1 region cannot rescue. Co-immunoprecipitation, siRNA knockdown, live-cell imaging of vesicle transport, Arf6-GTP pulldown, morphometry The Journal of biological chemistry Medium 25326380
2014 PKC phosphorylates cytohesin-2 in platelets; under basal conditions, cytohesin-2 keeps ARF6 constitutively GTP-loaded to suppress dense granule secretion; PKC-mediated phosphorylation of cytohesin-2 disrupts its interaction with ARF6, decreases ARF6-GTP, and promotes platelet secretion and aggregation. Immunoprecipitation + mass spectrometry, Western blot, SecinH3 pharmacology, lumi-aggregometry, flow cytometry Journal of thrombosis and haemostasis Medium 24581425
2014 Cytohesin-2 interacts with actinin-1 (ACTN1) via its polybasic C-terminal region (binding the ACTN1 EFh2 domain); this interaction is required for ARF6 activation at growth cones and neurite extension in N1E-115 cells; FRET assay with cell-permeable peptides confirms the interaction reduces ARF6-GTP at growth cones. Co-immunoprecipitation, pulldown, siRNA knockdown, ARF6-GTP pulldown, FRET with cell-permeable peptides, morphometry Cellular signalling Medium 22659138
2015 Cytohesin-2/ARNO localizes to EHD1-positive recycling endosomes and regulates recycling of R-Ras and α5-integrin to the plasma membrane via ARF GTPase activation; GEF-inactive ARNO (E156K) causes R-Ras accumulation on recycling endosomes and inhibits cell spreading. Co-localization by confocal microscopy, siRNA knockdown, dominant-negative ARNO (E156K), integrin recycling assay, cell spreading assay Molecular biology of the cell Medium 26378252
2015 RLIP76 links ARNO to activated R-Ras at recycling endosomes: RLIP76 N-terminus (residues 1–180) binds ARNO and residues 180–192 bind R-Ras, forming a ternary complex in Rab11-positive compartments that activates Arf6 and promotes cell spreading and migration. Co-immunoprecipitation, GST pulldown, domain deletion mutants, ARF6-GTP assay, cell spreading/migration assay, immunofluorescence colocalization Biochemical and biophysical research communications Medium 26498519
2015 Cytohesin-2/ARNO is required for Schwann cell myelination in the peripheral nervous system; conditional knockout of cytohesin-2 in Schwann cells reduces ARF6 activity, decreases myelin thickness in sciatic nerves, and reduces myelin protein zero (MPZ) expression. Schwann cell-specific conditional knockout mice, ARF6-GTP assay, electron microscopy of myelin thickness, Western blot for MPZ, SecinH3 pharmacology in culture Biochemical and biophysical research communications High 25824033
2016 ARNO and ARF1 are required for podosome assembly; ARNO colocalizes with adhesive rings of podosomes; ARF1 inhibition increases RhoA-GTP and myosin-IIA filament assembly, which suppresses podosomes; constitutively active ARF1 induces podosome precursors containing actin cores. siRNA knockdown, pharmacological inhibition (SecinH3, brefeldin A), ARF1-GTP assay, RhoA-GTP assay, immunofluorescence, matrix degradation assay The Journal of cell biology High 28007915
2018 INAVA's CUPID domain stably binds ARNO to promote lateral membrane F-actin assembly and barrier function; when ARNO is bound to CUPID, it promotes F-actin dynamics independent of its canonical GEF activity. Upon IL-1β, INAVA relocates to cytosolic puncta where CUPID amplifies TRAF6-dependent polyubiquitination/inflammatory signaling, while ARNO binding to CUPID negatively-regulates this inflammatory response. Co-immunoprecipitation, domain binding assays, siRNA knockdown, actin dynamics assay, ubiquitination assay, IL-1β signaling readout in epithelial cells and macrophages eLife High 30355448
2019 ARNO (cytohesin-2) binds the juxtamembrane (JM) intracellular segment of EGFR; NMR structural characterization reveals the ARNO-EGFR interaction interface, which shares features with but is distinct from JM interactions with calmodulin and anionic phospholipids; each interaction can be modulated by the others. NMR spectroscopy, in vitro binding assays Structure Medium 31780432
2021 Cytohesin-2 (CYTH2) forms a complex with CNKSR2; CYTH2 binding prevents proteasomal degradation of CNKSR2; shRNA knockdown of either CNKSR2 or CYTH2 in mouse hippocampal granule cell precursors results in abnormal localization and immature granule cell characteristics, demonstrating both are required for dentate granule cell development. Co-immunoprecipitation, proteasome inhibition, in vivo shRNA transduction, immunofluorescence, cell positioning assay The Journal of biological chemistry Medium 34800437
2021 Cytohesin-2 is enriched in perisynaptic membranes of dorsal horn neurons and forms a protein complex with mGluR5; cytohesin-2 conditional knockout mice show reduced mechanical allodynia in inflammatory and neuropathic pain models; cytohesin-2 mediates mGluR5-dependent ERK1/2 activation via Arf6 in spinal cord. Immunoelectron microscopy, co-immunoprecipitation, conditional KO mice, SecinH3 pharmacology, ARF1/6-GTP assay, ERK phosphorylation assay, behavioral pain assays Neurobiology of disease High 34390832
2022 Cytohesin-2 Tyr381 phosphorylation status is central to Schwann cell myelination; dephosphorylation by PTP4A1 reduces ARNO activity while SH2B1 interaction maintains Tyr381 phosphorylation and promotes myelination; knockin Y381F mice show reduced myelin thickness and ARF6 activity. Knockin mice (Y381F), Schwann cell-specific conditional KO of PTP4A1 and SH2B1, ARF6-GTP assay, co-immunoprecipitation, Western blot, electron microscopy of myelin Science signaling High 35077201
2022 CYTH2 is required for efficient influenza virus infection by mediating endosomal trafficking; CRISPR-Cas9 genome-wide screen identified CYTH2 as a host factor for influenza; SecinH3 treatment reduces influenza infection in vivo. Genome-wide CRISPR-Cas9 screen with survival selection, endosomal trafficking assay, SecinH3 in vivo treatment, viral infection assay Cell reports Medium 35354039
2022 FE65 (neuronal adaptor) interacts with ARNO and forms a ternary complex with ARF6; FE65 attenuates ARNO intramolecular autoinhibition and promotes ARNO dimerization, thereby potentiating ARNO-stimulated ARF6-mediated neurite outgrowth; FE65 mutations disrupting FE65-ARNO interaction abolish this potentiation. Co-immunoprecipitation, GST pulldown, ARF6-GTP assay, neurite morphometry, autoinhibition assay, dimerization assay Open biology Medium 36168805
2023 V-ATPase V0a1 subunit interacts with ARNO and promotes ARF6 activation during exocytosis in neuroendocrine cells; disruption of the V0a1–ARNO interaction inhibits PLD activation, phosphatidic acid synthesis, and alters the timing of membrane fusion events. Co-immunoprecipitation, ARF6-GTP assay, PLD activity assay, phosphatidic acid measurement, TIRF live imaging of exocytotic events Frontiers in molecular biosciences Medium 37091866
2026 Full knockout of cytohesin-2 in mice causes perinatal lethality within 20 h of birth; cytohesin-2 deficiency reduces Golgi volume (rescued by re-expression of cytohesin-2, even in an ARF-GEF-independent manner), impairs galactosylation, and markedly reduces global protein secretion in neonates. Global knockout mice, organellar proteomics by mass spectrometry, immunofluorescence (Golgi markers, PNA staining), quantitative secretome proteomics Life science alliance High 41672711

Source papers

Stage 0 corpus · 76 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2006 V-ATPase interacts with ARNO and Arf6 in early endosomes and regulates the protein degradative pathway. Nature cell biology 396 16415858
2001 Activation of ARF6 by ARNO stimulates epithelial cell migration through downstream activation of both Rac1 and phospholipase D. The Journal of cell biology 323 11481345
1998 Insulin-dependent translocation of ARNO to the plasma membrane of adipocytes requires phosphatidylinositol 3-kinase. Current biology : CB 230 9550703
1998 ARNO is a guanine nucleotide exchange factor for ADP-ribosylation factor 6. The Journal of biological chemistry 208 9417041
1998 A glutamic finger in the guanine nucleotide exchange factor ARNO displaces Mg2+ and the beta-phosphate to destabilize GDP on ARF1. The EMBO journal 164 9649435
1998 Structure of the guanine nucleotide exchange factor Sec7 domain of human arno and analysis of the interaction with ARF GTPase. Cell 161 9476900
1998 Structure of the Sec7 domain of the Arf exchange factor ARNO. Nature 154 9510256
1997 Role of protein-phospholipid interactions in the activation of ARF1 by the guanine nucleotide exchange factor Arno. The Journal of biological chemistry 149 9268368
2003 ARNO and ARF6 regulate axonal elongation and branching through downstream activation of phosphatidylinositol 4-phosphate 5-kinase alpha. Molecular biology of the cell 141 14565977
2012 Interleukin receptor activates a MYD88-ARNO-ARF6 cascade to disrupt vascular stability. Nature 135 23143332
2005 The DOCK180/Elmo complex couples ARNO-mediated Arf6 activation to the downstream activation of Rac1. Current biology : CB 130 16213822
2001 Intra-endosomal pH-sensitive recruitment of the Arf-nucleotide exchange factor ARNO and Arf6 from cytoplasm to proximal tubule endosomes. The Journal of biological chemistry 117 11278939
1998 Remodeling of the actin cytoskeleton is coordinately regulated by protein kinase C and the ADP-ribosylation factor nucleotide exchange factor ARNO. Molecular biology of the cell 114 9802902
2007 ARL4D recruits cytohesin-2/ARNO to modulate actin remodeling. Molecular biology of the cell 80 17804820
2012 Salmonella virulence effector SopE and Host GEF ARNO cooperate to recruit and activate WAVE to trigger bacterial invasion. Cell host & microbe 77 22341462
2000 The ADP ribosylation factor nucleotide exchange factor ARNO promotes beta-arrestin release necessary for luteinizing hormone/choriogonadotropin receptor desensitization. Proceedings of the National Academy of Sciences of the United States of America 70 10811902
2010 Kinetic studies of the Arf activator Arno on model membranes in the presence of Arf effectors suggest control by a positive feedback loop. The Journal of biological chemistry 66 21118813
2001 Specificities for the small G proteins ARF1 and ARF6 of the guanine nucleotide exchange factors ARNO and EFA6. The Journal of biological chemistry 62 11342560
2011 Aldolase directly interacts with ARNO and modulates cell morphology and acidic vesicle distribution. American journal of physiology. Cell physiology 59 21307348
1999 Regulation of ARNO nucleotide exchange by a PH domain electrostatic switch. Current biology : CB 58 10531036
2000 Binding of the PH and polybasic C-terminal domains of ARNO to phosphoinositides and to acidic lipids. Biochemistry 55 10801341
2003 Interaction protein for cytohesin exchange factors 1 (IPCEF1) binds cytohesin 2 and modifies its activity. The Journal of biological chemistry 53 12920129
2005 Heterotrimeric G protein-independent signaling of a G protein-coupled receptor. Direct binding of ARNO/cytohesin-2 to the carboxyl terminus of the A2A adenosine receptor is necessary for sustained activation of the ERK/MAP kinase pathway. The Journal of biological chemistry 52 16027149
2002 The N-terminal coiled coil domain of the cytohesin/ARNO family of guanine nucleotide exchange factors interacts with the scaffolding protein CASP. The Journal of biological chemistry 52 12052827
2004 Discriminatory aptamer reveals serum response element transcription regulated by cytohesin-2. Proceedings of the National Academy of Sciences of the United States of America 50 15277685
2010 Cytohesin-2/ARNO, through its interaction with focal adhesion adaptor protein paxillin, regulates preadipocyte migration via the downstream activation of Arf6. The Journal of biological chemistry 49 20525696
2011 Arf nucleotide binding site opener [ARNO] promotes sequential activation of Arf6, Cdc42 and Rac1 and insulin secretion in INS 832/13 β-cells and rat islets. Biochemical pharmacology 47 21276423
2009 GRASP and IPCEF promote ARF-to-Rac signaling and cell migration by coordinating the association of ARNO/cytohesin 2 with Dock180. Molecular biology of the cell 42 20016009
2007 The calcium-sensing receptor changes cell shape via a beta-arrestin-1 ARNO ARF6 ELMO protein network. Journal of cell science 40 17623778
1998 Overexpression of the ARF1 exchange factor ARNO inhibits the early secretory pathway and causes the disassembly of the Golgi complex. Journal of cell science 39 9788883
2016 Podosome assembly is controlled by the GTPase ARF1 and its nucleotide exchange factor ARNO. The Journal of cell biology 36 28007915
2022 Genome-wide CRISPR-Cas9 screening identifies the CYTH2 host gene as a potential therapeutic target of influenza viral infection. Cell reports 35 35354039
2013 The N termini of a-subunit isoforms are involved in signaling between vacuolar H+-ATPase (V-ATPase) and cytohesin-2. The Journal of biological chemistry 32 23288846
2003 The guanine nucleotide exchange factor ARNO mediates the activation of ARF and phospholipase D by insulin. BMC cell biology 30 12969509
2011 ARNO regulates VEGF-dependent tissue responses by stabilizing endothelial VEGFR-2 surface expression. Cardiovascular research 29 22002459
2009 Valproic acid-inducible Arl4D and cytohesin-2/ARNO, acting through the downstream Arf6, regulate neurite outgrowth in N1E-115 cells. Experimental cell research 29 19327349
2006 ARF6 activation by Galpha q signaling: Galpha q forms molecular complexes with ARNO and ARF6. Cellular signalling 27 16650966
2010 Specific motifs of the V-ATPase a2-subunit isoform interact with catalytic and regulatory domains of ARNO. Biochimica et biophysica acta 24 20153292
2018 INAVA-ARNO complexes bridge mucosal barrier function with inflammatory signaling. eLife 22 30355448
2014 Cytohesin 2/ARF6 regulates preadipocyte migration through the activation of ERK1/2. Biochemical pharmacology 21 25450674
2014 Cytohesins/ARNO: the function in colorectal cancer cells. PloS one 20 24618737
2006 ARNO through its coiled-coil domain regulates endocytosis at the apical surface of polarized epithelial cells. The Journal of biological chemistry 20 16484220
2001 Desensitization of the luteinizing hormone/choriogonadotropin receptor in ovarian follicular membranes is inhibited by catalytically inactive ARNO(+). The Journal of biological chemistry 20 11139567
2020 A view on the quality of diabetes care in Italy and the role of Diabetes Clinics from the 2018 ARNO Diabetes Observatory. Nutrition, metabolism, and cardiovascular diseases : NMCD 19 32998821
2014 The RLIP76 N-terminus binds ARNO to regulate PI 3-kinase, Arf6 and Rac signaling, cell spreading and migration. Biochemical and biophysical research communications 19 25450693
2015 RLIP76 regulates Arf6-dependent cell spreading and migration by linking ARNO with activated R-Ras at recycling endosomes. Biochemical and biophysical research communications 17 26498519
2014 Cytohesin-2 phosphorylation by protein kinase C relieves the constitutive suppression of platelet dense granule secretion by ADP-ribosylation factor 6. Journal of thrombosis and haemostasis : JTH 16 24581425
2014 Arf6 guanine nucleotide exchange factor cytohesin-2 binds to CCDC120 and is transported along neurites to mediate neurite growth. The Journal of biological chemistry 16 25326380
2007 A Role for ARF6 and ARNO in the regulation of endosomal dynamics in neurons. Traffic (Copenhagen, Denmark) 15 17897316
2018 Pallidin is a novel interacting protein for cytohesin-2 and regulates the early endosomal pathway and dendritic formation in neurons. Journal of neurochemistry 14 30151872
2013 Fragment-based identification of a locus in the Sec7 domain of Arno for the design of protein-protein interaction inhibitors. Journal of medicinal chemistry 14 24112024
2012 Arf6 guanine-nucleotide exchange factor, cytohesin-2, interacts with actinin-1 to regulate neurite extension. Cellular signalling 14 22659138
2015 Arf6 guanine-nucleotide exchange factor cytohesin-2 regulates myelination in nerves. Biochemical and biophysical research communications 13 25824033
2007 The N-terminal coiled-coil domain of the cytohesin/ARNO family of guanine nucleotide exchange factors interacts with Galphaq. Molecular and cellular biochemistry 13 17846866
2022 Blocking the cytohesin-2/ARF1 axis by SecinH3 ameliorates osteoclast-induced bone loss via attenuating JNK-mediated IRE1 endoribonuclease activity. Pharmacological research 12 36252772
2021 The synaptic scaffolding protein CNKSR2 interacts with CYTH2 to mediate hippocampal granule cell development. The Journal of biological chemistry 12 34800437
2015 ARF-GEF cytohesin-2/ARNO regulates R-Ras and α5-integrin recycling through an EHD1-positive compartment. Molecular biology of the cell 12 26378252
2004 Conformational states of the small G protein Arf-1 in complex with the guanine nucleotide exchange factor ARNO-Sec7. The Journal of biological chemistry 12 14739276
2012 Phagocytic NADPH oxidase links ARNO-Arf6 signaling pathway in glucose-stimulated insulin secretion from the pancreatic β-cell. Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology 10 23095975
2020 Arf6 Can Trigger Wave Regulatory Complex-Dependent Actin Assembly Independent of Arno. International journal of molecular sciences 9 32252226
2022 The adaptor SH2B1 and the phosphatase PTP4A1 regulate the phosphorylation of cytohesin-2 in myelinating Schwann cells in mice. Science signaling 8 35077201
2019 Molecular Architecture of a Network of Potential Intracellular EGFR Modulators: ARNO, CaM, Phospholipids, and the Juxtamembrane Segment. Structure (London, England : 1993) 8 31780432
2002 ARNO but not cytohesin-1 translocation is phosphatidylinositol 3-kinase-dependent in HL-60 cells. Journal of leukocyte biology 8 11927660
2022 ARNO is recruited by the neuronal adaptor FE65 to potentiate ARF6-mediated neurite outgrowth. Open biology 7 36168805
2021 Cytohesin-2 mediates group I metabotropic glutamate receptor-dependent mechanical allodynia through the activation of ADP ribosylation factor 6 in the spinal cord. Neurobiology of disease 7 34390832
2020 Autographivirinae Bacteriophage Arno 160 Infects Pectobacterium carotovorum via Depolymerization of the Bacterial O-Polysaccharide. International journal of molecular sciences 7 32365879
2021 S100A6, Calumenin and Cytohesin 2 as Biomarkers for Cutaneous Involvement in Systemic Sclerosis Patients: A Case Control Study. Journal of personalized medicine 6 34063287
2021 Initial treatment of diabetes in Italy. A nationwide population-based study from of the ARNO Diabetes Observatory. Nutrition, metabolism, and cardiovascular diseases : NMCD 6 34218990
2023 V-ATPase modulates exocytosis in neuroendocrine cells through the activation of the ARNO-Arf6-PLD pathway and the synthesis of phosphatidic acid. Frontiers in molecular biosciences 5 37091866
2020 The GEF Cytohesin-2/ARNO Mediates Resistin induced Phenotypic Switching in Vascular Smooth Muscle Cells. Scientific reports 5 32111889
2022 Cytohesin-2/ARNO: A Novel Bridge Between Cell Migration and Immunoregulation in Synovial Fibroblasts. Frontiers in immunology 3 35095899
2021 Deletion of Arno Reduces Eosinophilic Inflammation and Interleukin-5 Expression in a Murine Model of Rhinitis. Ear, nose, & throat journal 2 33393815
2005 Functional assay of ARNO and ARF6 in neurite elongation and branching. Methods in enzymology 2 16413274
2026 Cytohesin-2 is essential for the perinatal development of mice and regulates Golgi volume. Life science alliance 0 41672711
2025 G3BP1 maintains endothelial barrier integrity through dual mechanisms: direct stabilization of junction protein mRNAs and suppression of the inflammatory MYD88-ARNO-ARF6 pathway. Angiogenesis 0 40855241
1998 Human cts18.1 gene: chromosomal localization and PH-domain analysis. Genes & genetic systems 0 10085552