{"gene":"ARFGAP1","run_date":"2026-06-09T22:02:44","timeline":{"discoveries":[{"year":2003,"finding":"ArfGAP1-catalyzed GTP hydrolysis in Arf1 and COPI coat disassembly are stimulated over two orders of magnitude as membrane bilayer curvature increases toward that of a transport vesicle, establishing a mechanistic coupling between lipid packing/curvature and the timing of GTP hydrolysis during COPI vesicle budding.","method":"Time-resolved in vitro GTP hydrolysis and COPI disassembly assays on liposomes of controlled size","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 / Strong — quantitative reconstitution in vitro with defined liposome sizes, replicated and extended by multiple subsequent studies","pmids":["14654841"],"is_preprint":false},{"year":2005,"finding":"A central ~40-amino-acid ALPS (ArfGAP1 Lipid Packing Sensor) motif in ArfGAP1 is unstructured in solution but folds into an amphipathic helix upon inserting bulky hydrophobic residues between loosely packed lipids on highly curved membranes, and this motif is necessary for coupling ArfGAP1 GAP activity to membrane curvature.","method":"Site-directed mutagenesis, limited proteolysis, circular dichroism, liposome-binding assays","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — multiple orthogonal biochemical and biophysical methods (mutagenesis + CD + proteolysis + binding assay) in a single rigorous study, findings replicated by follow-up work","pmids":["15944734"],"is_preprint":false},{"year":2002,"finding":"ARFGAP1 promotes COPI vesicle formation and cargo sorting by functioning as a stoichiometric component of the COPI coat; it binds directly to dilysine motifs of cargo proteins, and its presence at levels comparable to coatomer on reconstituted vesicles supports a coat function rather than purely an uncoating function.","method":"Reconstituted COPI vesicle formation from Golgi membranes with purified components; direct binding assays between GAP and dilysine cargo motifs","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — full biochemical reconstitution with purified components plus direct binding assays; single lab but multiple orthogonal approaches","pmids":["12379802"],"is_preprint":false},{"year":2001,"finding":"The cytoplasmic domain of p24β1 cargo protein binds directly to ArfGAP1 and inhibits ArfGAP1-mediated GTP hydrolysis on Arf1 bound to liposomes and Golgi membranes, providing a mechanism whereby cargo suppresses GAP activity during vesicle formation.","method":"Synthetic peptide binding assays; in vitro GTP hydrolysis assays on liposomes and Golgi membranes","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro enzymatic assay with defined peptides on both liposomes and biological membranes, multiple readouts","pmids":["11748249"],"is_preprint":false},{"year":2005,"finding":"ArfGAP1 catalytic activity is required for COPI vesicle formation from Golgi membranes, and ARF1 (not ARFGAP1) plays a key direct role in binding SNARE cargo proteins; ArfGAP1 promotes coatomer binding to cargo proteins.","method":"In vitro COPI vesicle reconstitution from Golgi membranes; cargo-binding assays with purified components","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — biochemical reconstitution plus multiple binding assays; single lab with multiple orthogonal approaches","pmids":["15657398"],"is_preprint":false},{"year":2005,"finding":"FRAP analysis in living cells shows that ArfGAP1 undergoes fast cytosol/Golgi exchange, with ~40% of exchange dependent on engagement with coatomer and Arf1; permanent Arf1 activation traps ArfGAP1 on Golgi in a coatomer-dependent manner, demonstrating interdependent roles in the COPI coat assembly-disassembly cycle in vivo.","method":"FRAP of GFP-tagged ArfGAP1, Arf1, and coatomer in living cells; pharmacological Arf1 activation","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — live-cell FRAP with functional manipulation (Arf1 activation), multiple tagged proteins, quantitative analysis","pmids":["15795316"],"is_preprint":false},{"year":2007,"finding":"ArfGAP1 contains a second lipid-packing sensor motif (ALPS2) that also forms an amphipathic helix at the surface of small vesicles; ALPS2 reinforces membrane interaction ~40-fold relative to ALPS1 alone and contributes to Golgi localization of ArfGAP1 in vivo.","method":"Quantitative liposome-binding assays; circular dichroism; GFP localization in cells; mutagenesis","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — multiple orthogonal quantitative assays plus in vivo localization, single lab","pmids":["17253781"],"is_preprint":false},{"year":2005,"finding":"Golgi localization of ArfGAP1 depends on hydrophobic residues (including Leu-207 and Trp-211) within a short stretch (residues 204–214); alanine substitution of these residues strongly diminishes Golgi localization and reduces in vitro GAP activity on Golgi-bound Arf1.","method":"Site-directed mutagenesis; GFP-fusion localization; in vitro GAP activity assay on Golgi membranes","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — mutagenesis with parallel in vitro and in vivo readouts, multiple mutants tested","pmids":["16316994"],"is_preprint":false},{"year":2008,"finding":"Unlike ArfGAP2 and ArfGAP3 (which require coatomer for membrane recruitment), ArfGAP1 binds membranes directly in a curvature-dependent manner, demonstrating that ArfGAP1 is a membrane curvature-dependent ArfGAP with a distinct recruitment mechanism from the coatomer-dependent ArfGAPs.","method":"Membrane-binding assays with purified proteins; in vitro GAP activity assays in the presence/absence of coatomer","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — direct comparative biochemical assays with purified proteins, multiple ArfGAPs tested in parallel","pmids":["19015319"],"is_preprint":false},{"year":2008,"finding":"Catalytic amounts of ArfGAP1 significantly reduce the yield of purified COPI vesicles in a defined reconstitution assay, suggesting ArfGAP1 acts as an uncoating factor rather than a stoichiometric coat component under these conditions; Arf1 (not ArfGAP1) constitutes a stoichiometric component of the COPI coat.","method":"Defined reconstitution assay for COPI vesicle formation from Golgi membranes with titrated ArfGAP1; COPI vesicle purification and quantification","journal":"Traffic","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — rigorous reconstitution but single lab, directly contradicts other reconstitution studies; lower confidence due to controversy","pmids":["19055691"],"is_preprint":false},{"year":2009,"finding":"ArfGAP1 ALPS motifs bind exclusively to membrane tubes (positively curved membranes, radius threshold ~35 nm) and not to flat giant vesicle membranes; mixing catalytic amounts of ArfGAP1 with Arf1-GTP on tube-connected vesicles generates a smooth Arf1 gradient along the tube, demonstrating spatial regulation of Arf1 activity by membrane curvature sensing.","method":"Membrane tube pulling from giant vesicles using molecular motors and optical tweezers; fluorescence microscopy of labeled proteins","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — sophisticated reconstitution with optical tweezers and molecular motors, quantitative fluorescence measurement, multiple approaches","pmids":["19927117"],"is_preprint":false},{"year":2005,"finding":"ArfGAP1-induced GTP hydrolysis disassembles AP-1 adaptor oligomers from membranes; AP-1 stimulates ArfGAP1 activity in a reciprocal interaction, suggesting a role for AP-1 in regulating the Arf1 GTPase timer.","method":"In vitro reconstitution with purified AP-1, Arf1, liposomes, and ArfGAP1; gel filtration/sedimentation to detect oligomers","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro reconstitution, single lab, limited follow-up","pmids":["16093346"],"is_preprint":false},{"year":2010,"finding":"ArfGAP1 interacts with coat proteins through tryptophan-based motifs in its C-terminal region: a (329)WETF sequence binds clathrin adaptors AP-1 and AP-2, while the extreme C-terminal motif (405)AADEGWDNQNW is required for coatomer binding via the δ-subunit of the coatomer adaptor-like subcomplex.","method":"GST pulldown with peptides; mutagenesis; peptide competition; reporter fusion assay in vivo","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — multiple pulldown and competition experiments plus in vivo reporter assay, single lab","pmids":["20211604"],"is_preprint":false},{"year":2011,"finding":"Distinct regions of ARFGAP1 separately interact with AP-2 and coatomer; selectively disrupting the ARFGAP1–AP-2 interaction inhibits AP-2-dependent endocytosis, while disrupting ARFGAP1–coatomer interaction inhibits COPI transport, showing ARFGAP1 participates in both pathways through independent coat-binding regions.","method":"Co-immunoprecipitation; dominant-negative and deletion mutant analysis; transport assays","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal binding and functional rescue experiments, multiple selective mutants, published in high-quality journal","pmids":["21499258"],"is_preprint":false},{"year":2008,"finding":"ARFGAP1 binds directly to the C-terminus of GAT-1 (GABA transporter-1), and surface expression of a COPII-independent GAT-1 mutant (GAT1-RL/AS) requires ARFGAP1; correct axonal targeting of GAT-1 requires COPII-dependent ER export and is lost for the ARFGAP1-dependent bypass mutant.","method":"Co-immunoprecipitation/pull-down; siRNA knockdown; immunofluorescence in neuronal cells","journal":"The Journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — direct binding assay plus functional knockdown with axonal targeting readout, single lab","pmids":["19020038"],"is_preprint":false},{"year":2012,"finding":"ArfGAP1 acts as a GTPase-activating protein for LRRK2, markedly enhancing LRRK2 GTP hydrolysis activity; ArfGAP1 also promotes LRRK2 kinase activity; reciprocally, LRRK2 directly phosphorylates ArfGAP1 in vitro; silencing ArfGAP1 rescues G2019S LRRK2-induced neurite shortening in primary cortical neurons.","method":"Co-immunoprecipitation in mammalian cells and brain lysates; in vitro GTPase assay; in vitro kinase assay; siRNA knockdown with neurite morphology readout","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — in vitro enzymatic assays (GTPase and kinase) combined with co-IP in vivo and functional neuronal rescue, multiple orthogonal methods","pmids":["22363216"],"is_preprint":false},{"year":2012,"finding":"ArfGAP1 is the first identified GAP for LRRK2, binding predominantly via the WD40 and kinase domains of LRRK2; ArfGAP1 increases LRRK2 GTPase activity and regulates LRRK2 toxicity in vitro and in Drosophila; LRRK2 inhibits ArfGAP1 GAP activity while ArfGAP1 reduces LRRK2 autophosphorylation and kinase activity; Δ64-ArfGAP1 (dominant-negative) and shRNA knockdown of ArfGAP1 reduce LRRK2 toxicity.","method":"In vitro GTPase assay; in vitro kinase assay; co-immunoprecipitation; dominant-negative expression; Drosophila in vivo toxicity assay; shRNA knockdown","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — replicated across two independent labs (PMID 22363216 and 22423108), multiple enzymatic assays and in vivo validation","pmids":["22423108"],"is_preprint":false},{"year":2011,"finding":"ArfGAP1 promotes COPI vesicle formation by facilitating coatomer polymerization: ArfGAP1 increases coatomer-induced LUV deformation and, with cargo peptides, supports self-assembly of coatomer into spherical structures in the absence of membranes; ArfGAP1 overexpression in vivo induces vesicle accumulation while allowing normal COPI cargo trafficking.","method":"Electron microscopy of LUV deformation; coatomer self-assembly assay; in vivo overexpression with trafficking assay","journal":"Cellular logistics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple assays (EM, self-assembly, in vivo), single lab","pmids":["22279613"],"is_preprint":false},{"year":2011,"finding":"The non-catalytic C-terminal domain of ARFGAP1 (residues sufficient in GAP273 truncation) regulates actin cytoskeleton reorganization by inhibiting Rac1 activation upstream of Rac1; overexpression of constitutively active Rac1 or ARF6 suppresses the actin/spreading defects caused by this domain.","method":"Overexpression of truncation mutants; live-cell imaging; Rac1 activation assays; epistasis with constitutively active GTPases","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — genetic epistasis plus activation assays, multiple constructs, single lab","pmids":["21483700"],"is_preprint":false},{"year":2014,"finding":"HCV NS5A interacts with ARFGAP1 via a conserved cluster of positively charged amino acids in NS5A; this interaction hijacks ARFGAP1 to remove the PI4P phosphatase Sac1 (a COPI cargo) from the HCV replication site, thereby maintaining high PI4P levels required for HCV RNA replication.","method":"Co-immunoprecipitation; mutational analysis of NS5A; siRNA knockdown of ARFGAP1; PI4P level measurement; HCV replication assay","journal":"Journal of virology","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — co-IP plus functional knockdown and mutational analysis, single lab","pmids":["24623438"],"is_preprint":false},{"year":2014,"finding":"ARFGAP1 associates transiently with lipid droplets upon oleate addition in hepatocytes; cAMP addition shifts ARFGAP1 from lipid droplets to the Golgi; overexpression and knockdown of ARFGAP1 affect lipid droplet formation.","method":"Fluorescence microscopy; subcellular fractionation; overexpression and siRNA knockdown with lipid droplet quantification","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — direct localization experiments with functional gain/loss, single lab","pmids":["25397679"],"is_preprint":false},{"year":2021,"finding":"ArfGAP1 interacts with mTORC1 in the absence of amino acids and inhibits mTORC1 lysosomal localization and activation; the ALPS motifs of ArfGAP1 are required for this interaction and regulation of mTORC1 activity.","method":"Co-immunoprecipitation; lysosomal fractionation; mTORC1 activity assays; ALPS motif mutants; amino acid stimulation/deprivation","journal":"The EMBO journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP with functional mutants and lysosomal localization assay, single lab","pmids":["33988249"],"is_preprint":false},{"year":2021,"finding":"ArfGAP1 directly interacts with GTP-bound Arl1 and exhibits GAP activity toward Arl1 in vitro; ArfGAP1 overexpression (but not GAP activity-deficient mutant) causes dissociation of Arl1 from the TGN; ArfGAP1 knockdown impairs endosome-to-TGN retrograde transport of Shiga toxin B-subunit, similar to constitutively active Arl1.","method":"In vitro GTPase assay; activity pull-down; GFP-Arl1 localization; Shiga toxin trafficking assay; siRNA knockdown","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 1–2 / Moderate — in vitro enzymatic assay with direct binding plus in vivo functional assays, single lab","pmids":["33715220"],"is_preprint":false},{"year":2021,"finding":"ARFGAP1 promotes constitutive endocytosis of the glutamate transporter EAAT3 via its GAP activity using ARF6 as the substrate; a single phenylalanine residue (F508) in the EAAT3 C-terminus is required for ARFGAP1-promoted AP-2-dependent endocytosis; ARFGAP1 was identified as an EAAT3-interacting protein by mass spectrometry.","method":"Mass spectrometry; co-immunoprecipitation; GAP activity-deficient mutants; endocytosis assays; mutagenesis of F508","journal":"Frontiers in physiology","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — MS identification plus functional mutant analysis and endocytosis assay, single lab","pmids":["34040545"],"is_preprint":false},{"year":2017,"finding":"ArfGAP1 controls actin cytoskeleton reorganization downstream of Arf1 and phospholipase D1 (PLD1) via the M3 muscarinic receptor pathway, restricting Mycobacterium tuberculosis entry into epithelial cells; ArfGAP1 silencing leads to uncontrolled actin reorganization and increased Mtb uptake, while infection by Shigella flexneri and Yersinia pseudotuberculosis is unaffected.","method":"siRNA knockdown; actin imaging; bacterial entry assays with multiple pathogens; genetic pathway analysis","journal":"EMBO reports","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — loss-of-function with specific pathogen-specific phenotype and pathway placement, single lab","pmids":["29141986"],"is_preprint":false},{"year":2014,"finding":"Phosphatidic acid generated by phospholipase D2 (PLD2) is required for ArfGAP1 recruitment to Golgi membranes; inhibition or depletion of PLD2 prevents ArfGAP1 Golgi localization.","method":"PLD2 inhibition and siRNA depletion; fluorescence microscopy of ArfGAP1 localization","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — chemical inhibition and genetic depletion with direct localization readout, single lab","pmids":["25354038"],"is_preprint":false},{"year":2026,"finding":"LRRK2 phosphorylates ArfGAP1 within its ALPS2 motif at residues Ser284, Thr291, and Thr292 in vitro; phospho-mimicking mutations at these sites impair ArfGAP1 Golgi localization, redirect it to the cytoplasm, increase its interaction with mitochondrial VDAC proteins, block Golgi-derived vesicle formation after ER stress, and impair neurite outgrowth inhibition; phospho-null mutations protect against G2019S LRRK2 neurotoxicity.","method":"In vitro kinase assay with site-directed mutagenesis; phospho-null and phospho-mimetic mutant analysis; subcellular localization; interactome analysis; primary neuron morphology assay","journal":"Frontiers in molecular neuroscience","confidence":"Medium","confidence_rationale":"Tier 1–2 / Moderate — in vitro kinase assay with mutagenesis plus multiple functional readouts, single lab; peer-reviewed but very recent","pmids":["42094986"],"is_preprint":false},{"year":2023,"finding":"In Drosophila border cells, ArfGAP1 is required to maintain receptor tyrosine kinases (guidance receptors) at the plasma membrane; loss of ArfGAP1 increases receptor levels in late endosomes, increases late endosome/lysosome number and size, reduces directional chemotaxis, and genetic interactions suggest ArfGAP1 acts on Lrrk to regulate receptor sorting.","method":"Drosophila genetics; fluorescence imaging of receptor localization; endosome/lysosome quantification; genetic interaction analysis","journal":"iScience","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — in vivo loss-of-function with multiple cellular phenotypes and genetic epistasis, Drosophila model","pmids":["37599820"],"is_preprint":false},{"year":2025,"finding":"ATG2A localizes to extra-Golgi ARFGAP1-positive puncta during autophagosome biogenesis; ARFGAP1 itself is dispensable for macroautophagy but marks membranes that associate with the autophagic machinery; when autophagosome formation or early secretory pathway is perturbed, ARFGAP1 and Rab1a accumulate at ectopic sites with autophagic components.","method":"Proximity labeling (BioID); fluorescence microscopy; siRNA depletion; co-immunoprecipitation","journal":"bioRxiv","confidence":"Low","confidence_rationale":"Tier 2–3 / Weak — proximity labeling and imaging, preprint, ARFGAP1 itself shown dispensable for autophagy","pmids":["40196537"],"is_preprint":true}],"current_model":"ARFGAP1 is a Golgi-localized GTPase-activating protein for Arf1 whose catalytic activity is coupled to membrane curvature through two ALPS (ArfGAP1 Lipid Packing Sensor) motifs that fold into amphipathic helices on highly curved membranes; it promotes both COPI vesicle formation and cargo sorting by functioning as a component of the COPI coat (binding cargo dilysine motifs and coatomer via C-terminal tryptophan-based motifs), regulates AP-2-dependent endocytosis through a separate coat-binding region, acts as a GTPase-activating protein for Arl1 at the TGN, inhibits mTORC1 lysosomal recruitment via its ALPS motifs under amino-acid-deplete conditions, controls actin cytoskeleton dynamics by antagonizing Rac1 activation, and is itself a substrate of LRRK2 kinase whose phosphorylation of the ALPS2 motif (Ser284/Thr291/Thr292) redirects ArfGAP1 from the Golgi to the cytoplasm and modulates its activity, Golgi vesicle formation, and LRRK2-linked neuronal toxicity."},"narrative":{"mechanistic_narrative":"ARFGAP1 is a GTPase-activating protein for Arf1 that times GTP hydrolysis during COPI vesicle biogenesis by sensing membrane curvature, thereby coupling the Arf1 GTPase cycle to the geometry of the budding vesicle [PMID:14654841, PMID:19927117]. Curvature sensing is achieved through two ALPS (ArfGAP1 Lipid Packing Sensor) motifs that are unstructured in solution but fold into amphipathic helices when inserting hydrophobic residues into loosely packed lipids of highly curved membranes; ALPS1 couples GAP activity to curvature and ALPS2 reinforces membrane binding and Golgi targeting [PMID:15944734, PMID:17253781, PMID:19927117]. Unlike the coatomer-dependent ArfGAP2/3, ARFGAP1 binds membranes directly in a curvature-dependent manner, and its Golgi recruitment additionally depends on a hydrophobic stretch around Leu207/Trp211 and on phosphatidic acid generated by PLD2 [PMID:16316994, PMID:19015319, PMID:25354038]. Within the COPI system ARFGAP1 functions intimately with the coat: it binds dilysine cargo motifs, promotes coatomer binding to cargo and coatomer polymerization, and undergoes coatomer- and Arf1-dependent cytosol/Golgi exchange, while cargo proteins such as p24β1 suppress its GAP activity to license vesicle formation [PMID:12379802, PMID:11748249, PMID:15795316, PMID:22279613]. Through distinct C-terminal tryptophan-based motifs ARFGAP1 engages clathrin adaptors and coatomer separately, allowing it to participate in both COPI transport and AP-2-dependent endocytosis [PMID:20211604, PMID:21499258]. Beyond Arf1, ARFGAP1 acts as a GAP toward Arl1 at the TGN to control retrograde transport and toward ARF6 during endocytosis of membrane transporters, and it restrains actin reorganization by inhibiting Rac1 activation [PMID:33715220, PMID:34040545, PMID:21483700]. ARFGAP1 also intersects Parkinson's disease biology: it is a GAP for LRRK2 that enhances LRRK2 GTP hydrolysis and modulates LRRK2 kinase activity and neurotoxicity, and reciprocally it is a substrate of LRRK2, whose phosphorylation of the ALPS2 motif (Ser284/Thr291/Thr292) redirects ARFGAP1 from Golgi to cytoplasm and modulates Golgi vesicle formation and neurite outgrowth [PMID:22363216, PMID:22423108, PMID:42094986]. Additional roles include inhibition of mTORC1 lysosomal recruitment via its ALPS motifs under amino-acid deprivation [PMID:33988249].","teleology":[{"year":2002,"claim":"Established whether ARFGAP1 acts merely as an uncoating enzyme or as an integral part of the COPI machinery, by showing it is present stoichiometrically and binds cargo directly.","evidence":"Reconstituted COPI vesicle formation from Golgi membranes with purified components plus dilysine-cargo binding assays","pmids":["12379802"],"confidence":"High","gaps":["Stoichiometry of ARFGAP1 on vesicles later disputed","Did not resolve curvature dependence of GAP timing"]},{"year":2001,"claim":"Answered how cargo loading is coordinated with the Arf1 GTPase timer, showing the p24β1 cytoplasmic domain binds ARFGAP1 and inhibits its GAP activity.","evidence":"Synthetic peptide binding and in vitro GTP hydrolysis assays on liposomes and Golgi membranes","pmids":["11748249"],"confidence":"High","gaps":["Whether other cargo classes regulate GAP activity similarly","In vivo significance of inhibition during budding"]},{"year":2003,"claim":"Resolved why GTP hydrolysis is timed to vesicle budding, demonstrating that ARFGAP1 catalytic activity is dramatically stimulated as bilayer curvature increases.","evidence":"Time-resolved in vitro GTP hydrolysis and COPI disassembly assays on size-controlled liposomes","pmids":["14654841"],"confidence":"High","gaps":["Did not yet identify the structural sensor of curvature"]},{"year":2005,"claim":"Identified the molecular curvature sensor as the ALPS motif and showed Golgi localization depends on specific hydrophobic residues, while live-cell FRAP linked ARFGAP1 dynamics to coatomer and Arf1.","evidence":"Mutagenesis, CD, limited proteolysis, liposome binding, GFP localization, and FRAP in living cells","pmids":["15944734","16316994","15795316","15657398"],"confidence":"High","gaps":["Number of curvature-sensing motifs not yet established","How ALPS folding is regulated in vivo unknown"]},{"year":2007,"claim":"Demonstrated ARFGAP1 carries a second ALPS motif (ALPS2) that strongly reinforces curvature-dependent membrane binding and Golgi targeting.","evidence":"Quantitative liposome binding, CD, and GFP localization with mutagenesis","pmids":["17253781"],"confidence":"High","gaps":["Functional division of labor between ALPS1 and ALPS2 in vivo","Regulation of ALPS2 not addressed"]},{"year":2008,"claim":"Distinguished ARFGAP1 from paralogs by showing it binds membranes directly in a curvature-dependent manner rather than via coatomer, and linked it to neuronal cargo (GAT-1).","evidence":"Comparative membrane-binding and GAP assays with purified ArfGAP1/2/3; co-IP and siRNA with axonal targeting readout","pmids":["19015319","19020038"],"confidence":"High","gaps":["Mechanism of GAT-1 sorting by ARFGAP1 incomplete","Generality of cargo handling"]},{"year":2009,"claim":"Provided spatial proof of curvature-restricted activity, showing ALPS motifs bind only positively curved tubes and generate an Arf1 activity gradient.","evidence":"Membrane tube pulling with optical tweezers and molecular motors plus fluorescence microscopy","pmids":["19927117"],"confidence":"High","gaps":["Whether such gradients form on native Golgi","Coupling to coat assembly in cells"]},{"year":2009,"claim":"Challenged the stoichiometric-coat model by showing catalytic amounts of ARFGAP1 reduce COPI vesicle yield, favoring an uncoating role.","evidence":"Defined reconstitution with titrated ArfGAP1 and vesicle quantification","pmids":["19055691"],"confidence":"Medium","gaps":["Directly contradicts other reconstitution studies","Single-lab result not independently reconciled"]},{"year":2011,"claim":"Mapped how ARFGAP1 engages two coat systems through separate C-terminal motifs, enabling roles in both COPI transport and AP-2-dependent endocytosis, and clarified its action on coatomer polymerization.","evidence":"GST pulldowns, peptide competition, co-IP, selective disruption mutants and transport/EM assays","pmids":["20211604","21499258","22279613"],"confidence":"High","gaps":["How dual coat engagement is temporally segregated","Whether AP-1 vs AP-2 binding is regulated"]},{"year":2012,"claim":"Established a reciprocal enzymatic relationship with the Parkinson's kinase LRRK2 — ARFGAP1 as a GAP for LRRK2 and a substrate that modulates LRRK2 toxicity.","evidence":"In vitro GTPase and kinase assays, co-IP in cells and brain, siRNA/dominant-negative and Drosophila toxicity readouts","pmids":["22363216","22423108"],"confidence":"High","gaps":["Phosphosites on ARFGAP1 not yet mapped","Physiological context of LRRK2 regulation"]},{"year":2014,"claim":"Extended ARFGAP1 function to lipid droplet biology, viral hijacking, and PLD2-dependent Golgi recruitment.","evidence":"Microscopy, fractionation, co-IP, siRNA, PI4P measurement, and PLD2 inhibition/depletion","pmids":["25397679","24623438","25354038"],"confidence":"Medium","gaps":["Mechanism of lipid droplet association unclear","Single-lab observations for each role"]},{"year":2017,"claim":"Placed ARFGAP1 in actin-cytoskeleton control downstream of Arf1/PLD1, restraining Rac1 and limiting bacterial entry.","evidence":"siRNA, actin imaging, Rac1 activation assays and pathogen entry assays with epistasis","pmids":["29141986","21483700"],"confidence":"Medium","gaps":["Direct molecular target in Rac1 inhibition not defined","Whether catalytic vs non-catalytic domain mediates each effect"]},{"year":2021,"claim":"Broadened the GAP repertoire to Arl1 at the TGN and ARF6 in endocytosis, and revealed ALPS-dependent inhibition of mTORC1 lysosomal recruitment under amino-acid deprivation.","evidence":"In vitro GTPase/activity assays, GFP-Arl1 and EAAT3 endocytosis assays, co-IP, lysosomal fractionation and ALPS mutants","pmids":["33715220","34040545","33988249"],"confidence":"Medium","gaps":["How substrate selection among Arf1/Arl1/ARF6 is achieved","Mechanism of mTORC1 inhibition single-lab"]},{"year":2026,"claim":"Defined the LRRK2 phosphorylation sites on the ALPS2 motif and showed phosphorylation redirects ARFGAP1 from Golgi to cytoplasm, altering vesicle formation and neurotoxicity.","evidence":"In vitro kinase assays with site-directed mutagenesis, phospho-mimetic/null mutants, localization, interactome and primary neuron morphology","pmids":["42094986"],"confidence":"Medium","gaps":["In vivo confirmation of phosphoregulation","Functional meaning of VDAC interaction","Single-lab and very recent"]},{"year":null,"claim":"How ARFGAP1's many context-specific roles — COPI/AP coat cycling, Arl1/ARF6 GAP activity, mTORC1, actin, and LRRK2 crosstalk — are integrated and regulated within a single cell remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["Unified model of substrate/pathway selection lacking","Stoichiometric-coat versus uncoating controversy unsettled","Physiological relevance of LRRK2 phosphoregulation in vivo unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,22,23,15,16]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[1,6,10,25]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[15,16,26]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[2,12,13]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[6,7,25,5]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[5,26]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[2,9,17]},{"term_id":"GO:0005811","term_label":"lipid droplet","supporting_discovery_ids":[20]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[0,2,4,13,22]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[14,22,23]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[15,16,19,24,26]}],"complexes":["COPI coat"],"partners":["ARF1","ARL1","ARF6","LRRK2","COPB1","AP-2","AP-1","TMED2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8N6T3","full_name":"ADP-ribosylation factor GTPase-activating protein 1","aliases":["ADP-ribosylation factor 1 GTPase-activating protein","ARF1 GAP","ARF1-directed GTPase-activating protein"],"length_aa":406,"mass_kda":44.7,"function":"GTPase-activating protein (GAP) for the ADP ribosylation factor 1 (ARF1). Involved in membrane trafficking and /or vesicle transport. Promotes hydrolysis of the ARF1-bound GTP and thus, is required for the dissociation of coat proteins from Golgi-derived membranes and vesicles, a prerequisite for vesicle's fusion with target compartment. Probably regulates ARF1-mediated transport via its interaction with the KDELR proteins and TMED2. Overexpression induces the redistribution of the entire Golgi complex to the endoplasmic reticulum, as when ARF1 is deactivated. Its activity is stimulated by phosphoinosides and inhibited by phosphatidylcholine (By similarity)","subcellular_location":"Cytoplasm; Golgi apparatus","url":"https://www.uniprot.org/uniprotkb/Q8N6T3/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ARFGAP1","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000101199","cell_line_id":"CID000922","localizations":[{"compartment":"golgi","grade":3},{"compartment":"cytoplasmic","grade":2},{"compartment":"vesicles","grade":1}],"interactors":[{"gene":"COPG2","stoichiometry":0.2},{"gene":"CD2AP","stoichiometry":0.2},{"gene":"LAMP1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000922","total_profiled":1310},"omim":[{"mim_id":"620983","title":"IMMUNODEFICIENCY 128; IMD128","url":"https://www.omim.org/entry/620983"},{"mim_id":"615525","title":"COATOMER PROTEIN COMPLEX, SUBUNIT GAMMA-1; COPG1","url":"https://www.omim.org/entry/615525"},{"mim_id":"612439","title":"ADP-RIBOSYLATION FACTOR GTPase-ACTIVATING PROTEIN 3; ARFGAP3","url":"https://www.omim.org/entry/612439"},{"mim_id":"608564","title":"GIT ArfGAP 2; GIT2","url":"https://www.omim.org/entry/608564"},{"mim_id":"608377","title":"ADP-RIBOSYLATION FACTOR GTPase-ACTIVATING PROTEIN 1; ARFGAP1","url":"https://www.omim.org/entry/608377"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Golgi apparatus","reliability":"Approved"},{"location":"Nuclear membrane","reliability":"Additional"},{"location":"Vesicles","reliability":"Additional"},{"location":"Primary cilium","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/ARFGAP1"},"hgnc":{"alias_symbol":["FLJ10767","bA261N11.3"],"prev_symbol":["ARF1GAP"]},"alphafold":{"accession":"Q8N6T3","domains":[{"cath_id":"1.10.220.150","chopping":"5-121","consensus_level":"high","plddt":96.5905,"start":5,"end":121}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8N6T3","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8N6T3-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8N6T3-F1-predicted_aligned_error_v6.png","plddt_mean":60.84},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ARFGAP1","jax_strain_url":"https://www.jax.org/strain/search?query=ARFGAP1"},"sequence":{"accession":"Q8N6T3","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8N6T3.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8N6T3/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8N6T3"}},"corpus_meta":[{"pmid":"15944734","id":"PMC_15944734","title":"ArfGAP1 responds to membrane curvature through the folding of a lipid packing sensor motif.","date":"2005","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/15944734","citation_count":316,"is_preprint":false},{"pmid":"14654841","id":"PMC_14654841","title":"Lipid packing sensed by ArfGAP1 couples COPI coat disassembly to membrane bilayer curvature.","date":"2003","source":"Nature","url":"https://pubmed.ncbi.nlm.nih.gov/14654841","citation_count":261,"is_preprint":false},{"pmid":"12379802","id":"PMC_12379802","title":"ARFGAP1 promotes the formation of COPI vesicles, suggesting function as a component of the coat.","date":"2002","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/12379802","citation_count":161,"is_preprint":false},{"pmid":"11748249","id":"PMC_11748249","title":"Sorting of Golgi resident proteins into different subpopulations of COPI vesicles: a role for ArfGAP1.","date":"2001","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/11748249","citation_count":147,"is_preprint":false},{"pmid":"22363216","id":"PMC_22363216","title":"GTPase activity and neuronal toxicity of Parkinson's disease-associated LRRK2 is regulated by ArfGAP1.","date":"2012","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/22363216","citation_count":112,"is_preprint":false},{"pmid":"15657398","id":"PMC_15657398","title":"ARFGAP1 plays a central role in coupling COPI cargo sorting with vesicle formation.","date":"2005","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/15657398","citation_count":110,"is_preprint":false},{"pmid":"17253781","id":"PMC_17253781","title":"Two lipid-packing sensor motifs contribute to the sensitivity of ArfGAP1 to membrane curvature.","date":"2007","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/17253781","citation_count":100,"is_preprint":false},{"pmid":"22423108","id":"PMC_22423108","title":"ArfGAP1 is a GTPase activating protein for LRRK2: reciprocal regulation of ArfGAP1 by LRRK2.","date":"2012","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/22423108","citation_count":90,"is_preprint":false},{"pmid":"15795316","id":"PMC_15795316","title":"ArfGAP1 dynamics and its role in COPI coat assembly on Golgi membranes of living cells.","date":"2005","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/15795316","citation_count":74,"is_preprint":false},{"pmid":"19927117","id":"PMC_19927117","title":"ArfGAP1 generates an Arf1 gradient on continuous lipid membranes displaying flat and curved regions.","date":"2009","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/19927117","citation_count":62,"is_preprint":false},{"pmid":"19015319","id":"PMC_19015319","title":"Differential roles of ArfGAP1, ArfGAP2, and ArfGAP3 in COPI trafficking.","date":"2008","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/19015319","citation_count":61,"is_preprint":false},{"pmid":"19055691","id":"PMC_19055691","title":"ArfGAP1 activity and COPI vesicle biogenesis.","date":"2008","source":"Traffic (Copenhagen, Denmark)","url":"https://pubmed.ncbi.nlm.nih.gov/19055691","citation_count":43,"is_preprint":false},{"pmid":"21499258","id":"PMC_21499258","title":"ARFGAP1 promotes AP-2-dependent endocytosis.","date":"2011","source":"Nature cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/21499258","citation_count":39,"is_preprint":false},{"pmid":"24623438","id":"PMC_24623438","title":"Hepatitis C virus NS5A hijacks ARFGAP1 to maintain a phosphatidylinositol 4-phosphate-enriched microenvironment.","date":"2014","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/24623438","citation_count":34,"is_preprint":false},{"pmid":"33988249","id":"PMC_33988249","title":"ArfGAP1 inhibits mTORC1 lysosomal localization and activation.","date":"2021","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/33988249","citation_count":30,"is_preprint":false},{"pmid":"19020038","id":"PMC_19020038","title":"Sec24- and ARFGAP1-dependent trafficking of GABA transporter-1 is a prerequisite for correct axonal targeting.","date":"2008","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/19020038","citation_count":30,"is_preprint":false},{"pmid":"16093346","id":"PMC_16093346","title":"Oligomerization and dissociation of AP-1 adaptors are regulated by cargo signals and by ArfGAP1-induced GTP hydrolysis.","date":"2005","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/16093346","citation_count":24,"is_preprint":false},{"pmid":"16316994","id":"PMC_16316994","title":"Golgi localization determinants in ArfGAP1 and in new tissue-specific ArfGAP1 isoforms.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16316994","citation_count":22,"is_preprint":false},{"pmid":"22806901","id":"PMC_22806901","title":"ArfGAP1 function in COPI mediated membrane traffic: currently debated models and comparison to other coat-binding ArfGAPs.","date":"2012","source":"Histology and histopathology","url":"https://pubmed.ncbi.nlm.nih.gov/22806901","citation_count":21,"is_preprint":false},{"pmid":"29141986","id":"PMC_29141986","title":"ArfGAP1 restricts Mycobacterium tuberculosis entry by controlling the actin cytoskeleton.","date":"2017","source":"EMBO reports","url":"https://pubmed.ncbi.nlm.nih.gov/29141986","citation_count":20,"is_preprint":false},{"pmid":"20211604","id":"PMC_20211604","title":"ArfGAP1 interacts with coat proteins through tryptophan-based motifs.","date":"2010","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/20211604","citation_count":18,"is_preprint":false},{"pmid":"22279613","id":"PMC_22279613","title":"ArfGAP1 promotes COPI vesicle formation by facilitating coatomer polymerization.","date":"2011","source":"Cellular logistics","url":"https://pubmed.ncbi.nlm.nih.gov/22279613","citation_count":17,"is_preprint":false},{"pmid":"18195007","id":"PMC_18195007","title":"Topology of amphipathic motifs mediating Golgi localization in ArfGAP1 and its splice isoforms.","date":"2008","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/18195007","citation_count":17,"is_preprint":false},{"pmid":"23752192","id":"PMC_23752192","title":"Involvement of small ArfGAP1 (SMAP1), a novel Arf6-specific GTPase-activating protein, in microsatellite instability oncogenesis.","date":"2013","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/23752192","citation_count":15,"is_preprint":false},{"pmid":"21686252","id":"PMC_21686252","title":"GAPs: Terminator versus effector functions and the role(s) of ArfGAP1 in vesicle biogenesis.","date":"2011","source":"Cellular logistics","url":"https://pubmed.ncbi.nlm.nih.gov/21686252","citation_count":15,"is_preprint":false},{"pmid":"25397679","id":"PMC_25397679","title":"ARFGAP1 is dynamically associated with lipid droplets in hepatocytes.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/25397679","citation_count":14,"is_preprint":false},{"pmid":"33721634","id":"PMC_33721634","title":"ARFGAP1 binds to classical swine fever virus NS5A protein and enhances CSFV replication in PK-15 cells.","date":"2021","source":"Veterinary microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/33721634","citation_count":11,"is_preprint":false},{"pmid":"34096300","id":"PMC_34096300","title":"Glutamine Regulates Cell Growth and Casein Synthesis through the CYTHs/ARFGAP1-Arf1-mTORC1 Pathway in Bovine Mammary Epithelial Cells.","date":"2021","source":"Journal of agricultural and food chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/34096300","citation_count":11,"is_preprint":false},{"pmid":"33277377","id":"PMC_33277377","title":"BPIFB3 interacts with ARFGAP1 and TMED9 to regulate non-canonical autophagy and RNA virus infection.","date":"2021","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/33277377","citation_count":10,"is_preprint":false},{"pmid":"33715220","id":"PMC_33715220","title":"ArfGAP1 acts as a GTPase-activating protein for human ADP-ribosylation factor-like 1 protein.","date":"2021","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/33715220","citation_count":8,"is_preprint":false},{"pmid":"34040545","id":"PMC_34040545","title":"Constitutive Endocytosis of the Neuronal Glutamate Transporter Excitatory Amino Acid Transporter-3 Requires ARFGAP1.","date":"2021","source":"Frontiers in physiology","url":"https://pubmed.ncbi.nlm.nih.gov/34040545","citation_count":8,"is_preprint":false},{"pmid":"26565960","id":"PMC_26565960","title":"Identification of Atg2 and ArfGAP1 as Candidate Genetic Modifiers of the Eye Pigmentation Phenotype of Adaptor Protein-3 (AP-3) Mutants in Drosophila melanogaster.","date":"2015","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/26565960","citation_count":8,"is_preprint":false},{"pmid":"21483700","id":"PMC_21483700","title":"The non-catalytic carboxyl-terminal domain of ARFGAP1 regulates actin cytoskeleton reorganization by antagonizing the activation of Rac1.","date":"2011","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/21483700","citation_count":8,"is_preprint":false},{"pmid":"25354038","id":"PMC_25354038","title":"Phospholipase D2 is involved in the formation of Golgi tubules and ArfGAP1 recruitment.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/25354038","citation_count":6,"is_preprint":false},{"pmid":"29240824","id":"PMC_29240824","title":"High abundance of ArfGAP1 found in the mossy fibers in hilus of the dentate gyrus region of the mouse brain.","date":"2017","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/29240824","citation_count":4,"is_preprint":false},{"pmid":"30249399","id":"PMC_30249399","title":"Detecting phospholipase activity with the amphipathic lipid packing sensor motif of ArfGAP1.","date":"2018","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/30249399","citation_count":2,"is_preprint":false},{"pmid":"40196537","id":"PMC_40196537","title":"ATG2A engages Rab1a and ARFGAP1 positive membranes during autophagosome biogenesis.","date":"2025","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/40196537","citation_count":1,"is_preprint":false},{"pmid":"37566088","id":"PMC_37566088","title":"C9orf72 Toxic Species Affect ArfGAP-1 Function.","date":"2023","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/37566088","citation_count":1,"is_preprint":false},{"pmid":"37599820","id":"PMC_37599820","title":"ArfGAP1 regulates the endosomal sorting of guidance receptors to promote directed collective cell migration in vivo.","date":"2023","source":"iScience","url":"https://pubmed.ncbi.nlm.nih.gov/37599820","citation_count":1,"is_preprint":false},{"pmid":"41163005","id":"PMC_41163005","title":"ARFGAP1 serves as a critical host factor during E30 infection: QS11 inhibits viral pathogenesis in hFcRn-IFNAR-/- mice.","date":"2025","source":"Virology journal","url":"https://pubmed.ncbi.nlm.nih.gov/41163005","citation_count":0,"is_preprint":false},{"pmid":"42094986","id":"PMC_42094986","title":"LRRK2 regulates ArfGAP1 membrane localization, activity and neuronal integrity via phosphorylation within its lipid-sensing ALPS2 motif.","date":"2026","source":"Frontiers in molecular neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/42094986","citation_count":0,"is_preprint":false},{"pmid":"41648595","id":"PMC_41648595","title":"LRRK2 regulates ArfGAP1 membrane localization, activity and neuronal toxicity via phosphorylation within its lipid-sensing ALPS2 motif.","date":"2026","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/41648595","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.03.24.645038","title":"ATG2A interacts with RAB1A and ARFGAP1 positive membranes during autophagosome biogenesis","date":"2025-03-25","source":"bioRxiv","url":"https://doi.org/10.1101/2025.03.24.645038","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.01.22.634236","title":"JNK regulates β3-containing GABAAR expression at the cell surface via the receptor clustering protein GIT1 (ArfGAP1)","date":"2025-01-25","source":"bioRxiv","url":"https://doi.org/10.1101/2025.01.22.634236","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":23175,"output_tokens":7400,"usd":0.090262,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":16216,"output_tokens":4767,"usd":0.100127,"stage2_stop_reason":"end_turn"},"total_usd":0.190389,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"Looking at the papers, I need to identify which ones are about the canonical ARFGAP1 protein (also known as ARF1GAP). Paper [24] is about SMAP1 (a different gene, Arf6-specific GAP). Paper [44] is about GIT1 (G protein-coupled receptor kinase interacting ArfGAP 1), which shares the alias ArfGAP1 but is actually a different gene (AGAP2/GIT1 family). I'll exclude [24] and [44].\n\nPaper [32] is about Drosophila ArfGAP1 as a genetic modifier — this is a fly ortholog study, includable.\nPaper [39] is Drosophila border cell migration study with ArfGAP1 — includable as ortholog.\n\nNow extracting mechanistic discoveries:\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2003,\n      \"finding\": \"ArfGAP1-catalyzed GTP hydrolysis in Arf1 and COPI coat disassembly are stimulated over two orders of magnitude as membrane bilayer curvature increases toward that of a transport vesicle, establishing a mechanistic coupling between lipid packing/curvature and the timing of GTP hydrolysis during COPI vesicle budding.\",\n      \"method\": \"Time-resolved in vitro GTP hydrolysis and COPI disassembly assays on liposomes of controlled size\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — quantitative reconstitution in vitro with defined liposome sizes, replicated and extended by multiple subsequent studies\",\n      \"pmids\": [\"14654841\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"A central ~40-amino-acid ALPS (ArfGAP1 Lipid Packing Sensor) motif in ArfGAP1 is unstructured in solution but folds into an amphipathic helix upon inserting bulky hydrophobic residues between loosely packed lipids on highly curved membranes, and this motif is necessary for coupling ArfGAP1 GAP activity to membrane curvature.\",\n      \"method\": \"Site-directed mutagenesis, limited proteolysis, circular dichroism, liposome-binding assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — multiple orthogonal biochemical and biophysical methods (mutagenesis + CD + proteolysis + binding assay) in a single rigorous study, findings replicated by follow-up work\",\n      \"pmids\": [\"15944734\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"ARFGAP1 promotes COPI vesicle formation and cargo sorting by functioning as a stoichiometric component of the COPI coat; it binds directly to dilysine motifs of cargo proteins, and its presence at levels comparable to coatomer on reconstituted vesicles supports a coat function rather than purely an uncoating function.\",\n      \"method\": \"Reconstituted COPI vesicle formation from Golgi membranes with purified components; direct binding assays between GAP and dilysine cargo motifs\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — full biochemical reconstitution with purified components plus direct binding assays; single lab but multiple orthogonal approaches\",\n      \"pmids\": [\"12379802\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"The cytoplasmic domain of p24β1 cargo protein binds directly to ArfGAP1 and inhibits ArfGAP1-mediated GTP hydrolysis on Arf1 bound to liposomes and Golgi membranes, providing a mechanism whereby cargo suppresses GAP activity during vesicle formation.\",\n      \"method\": \"Synthetic peptide binding assays; in vitro GTP hydrolysis assays on liposomes and Golgi membranes\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro enzymatic assay with defined peptides on both liposomes and biological membranes, multiple readouts\",\n      \"pmids\": [\"11748249\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"ArfGAP1 catalytic activity is required for COPI vesicle formation from Golgi membranes, and ARF1 (not ARFGAP1) plays a key direct role in binding SNARE cargo proteins; ArfGAP1 promotes coatomer binding to cargo proteins.\",\n      \"method\": \"In vitro COPI vesicle reconstitution from Golgi membranes; cargo-binding assays with purified components\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — biochemical reconstitution plus multiple binding assays; single lab with multiple orthogonal approaches\",\n      \"pmids\": [\"15657398\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"FRAP analysis in living cells shows that ArfGAP1 undergoes fast cytosol/Golgi exchange, with ~40% of exchange dependent on engagement with coatomer and Arf1; permanent Arf1 activation traps ArfGAP1 on Golgi in a coatomer-dependent manner, demonstrating interdependent roles in the COPI coat assembly-disassembly cycle in vivo.\",\n      \"method\": \"FRAP of GFP-tagged ArfGAP1, Arf1, and coatomer in living cells; pharmacological Arf1 activation\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — live-cell FRAP with functional manipulation (Arf1 activation), multiple tagged proteins, quantitative analysis\",\n      \"pmids\": [\"15795316\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"ArfGAP1 contains a second lipid-packing sensor motif (ALPS2) that also forms an amphipathic helix at the surface of small vesicles; ALPS2 reinforces membrane interaction ~40-fold relative to ALPS1 alone and contributes to Golgi localization of ArfGAP1 in vivo.\",\n      \"method\": \"Quantitative liposome-binding assays; circular dichroism; GFP localization in cells; mutagenesis\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — multiple orthogonal quantitative assays plus in vivo localization, single lab\",\n      \"pmids\": [\"17253781\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Golgi localization of ArfGAP1 depends on hydrophobic residues (including Leu-207 and Trp-211) within a short stretch (residues 204–214); alanine substitution of these residues strongly diminishes Golgi localization and reduces in vitro GAP activity on Golgi-bound Arf1.\",\n      \"method\": \"Site-directed mutagenesis; GFP-fusion localization; in vitro GAP activity assay on Golgi membranes\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — mutagenesis with parallel in vitro and in vivo readouts, multiple mutants tested\",\n      \"pmids\": [\"16316994\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Unlike ArfGAP2 and ArfGAP3 (which require coatomer for membrane recruitment), ArfGAP1 binds membranes directly in a curvature-dependent manner, demonstrating that ArfGAP1 is a membrane curvature-dependent ArfGAP with a distinct recruitment mechanism from the coatomer-dependent ArfGAPs.\",\n      \"method\": \"Membrane-binding assays with purified proteins; in vitro GAP activity assays in the presence/absence of coatomer\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — direct comparative biochemical assays with purified proteins, multiple ArfGAPs tested in parallel\",\n      \"pmids\": [\"19015319\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Catalytic amounts of ArfGAP1 significantly reduce the yield of purified COPI vesicles in a defined reconstitution assay, suggesting ArfGAP1 acts as an uncoating factor rather than a stoichiometric coat component under these conditions; Arf1 (not ArfGAP1) constitutes a stoichiometric component of the COPI coat.\",\n      \"method\": \"Defined reconstitution assay for COPI vesicle formation from Golgi membranes with titrated ArfGAP1; COPI vesicle purification and quantification\",\n      \"journal\": \"Traffic\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — rigorous reconstitution but single lab, directly contradicts other reconstitution studies; lower confidence due to controversy\",\n      \"pmids\": [\"19055691\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"ArfGAP1 ALPS motifs bind exclusively to membrane tubes (positively curved membranes, radius threshold ~35 nm) and not to flat giant vesicle membranes; mixing catalytic amounts of ArfGAP1 with Arf1-GTP on tube-connected vesicles generates a smooth Arf1 gradient along the tube, demonstrating spatial regulation of Arf1 activity by membrane curvature sensing.\",\n      \"method\": \"Membrane tube pulling from giant vesicles using molecular motors and optical tweezers; fluorescence microscopy of labeled proteins\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — sophisticated reconstitution with optical tweezers and molecular motors, quantitative fluorescence measurement, multiple approaches\",\n      \"pmids\": [\"19927117\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"ArfGAP1-induced GTP hydrolysis disassembles AP-1 adaptor oligomers from membranes; AP-1 stimulates ArfGAP1 activity in a reciprocal interaction, suggesting a role for AP-1 in regulating the Arf1 GTPase timer.\",\n      \"method\": \"In vitro reconstitution with purified AP-1, Arf1, liposomes, and ArfGAP1; gel filtration/sedimentation to detect oligomers\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro reconstitution, single lab, limited follow-up\",\n      \"pmids\": [\"16093346\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"ArfGAP1 interacts with coat proteins through tryptophan-based motifs in its C-terminal region: a (329)WETF sequence binds clathrin adaptors AP-1 and AP-2, while the extreme C-terminal motif (405)AADEGWDNQNW is required for coatomer binding via the δ-subunit of the coatomer adaptor-like subcomplex.\",\n      \"method\": \"GST pulldown with peptides; mutagenesis; peptide competition; reporter fusion assay in vivo\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — multiple pulldown and competition experiments plus in vivo reporter assay, single lab\",\n      \"pmids\": [\"20211604\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Distinct regions of ARFGAP1 separately interact with AP-2 and coatomer; selectively disrupting the ARFGAP1–AP-2 interaction inhibits AP-2-dependent endocytosis, while disrupting ARFGAP1–coatomer interaction inhibits COPI transport, showing ARFGAP1 participates in both pathways through independent coat-binding regions.\",\n      \"method\": \"Co-immunoprecipitation; dominant-negative and deletion mutant analysis; transport assays\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal binding and functional rescue experiments, multiple selective mutants, published in high-quality journal\",\n      \"pmids\": [\"21499258\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"ARFGAP1 binds directly to the C-terminus of GAT-1 (GABA transporter-1), and surface expression of a COPII-independent GAT-1 mutant (GAT1-RL/AS) requires ARFGAP1; correct axonal targeting of GAT-1 requires COPII-dependent ER export and is lost for the ARFGAP1-dependent bypass mutant.\",\n      \"method\": \"Co-immunoprecipitation/pull-down; siRNA knockdown; immunofluorescence in neuronal cells\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — direct binding assay plus functional knockdown with axonal targeting readout, single lab\",\n      \"pmids\": [\"19020038\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"ArfGAP1 acts as a GTPase-activating protein for LRRK2, markedly enhancing LRRK2 GTP hydrolysis activity; ArfGAP1 also promotes LRRK2 kinase activity; reciprocally, LRRK2 directly phosphorylates ArfGAP1 in vitro; silencing ArfGAP1 rescues G2019S LRRK2-induced neurite shortening in primary cortical neurons.\",\n      \"method\": \"Co-immunoprecipitation in mammalian cells and brain lysates; in vitro GTPase assay; in vitro kinase assay; siRNA knockdown with neurite morphology readout\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro enzymatic assays (GTPase and kinase) combined with co-IP in vivo and functional neuronal rescue, multiple orthogonal methods\",\n      \"pmids\": [\"22363216\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"ArfGAP1 is the first identified GAP for LRRK2, binding predominantly via the WD40 and kinase domains of LRRK2; ArfGAP1 increases LRRK2 GTPase activity and regulates LRRK2 toxicity in vitro and in Drosophila; LRRK2 inhibits ArfGAP1 GAP activity while ArfGAP1 reduces LRRK2 autophosphorylation and kinase activity; Δ64-ArfGAP1 (dominant-negative) and shRNA knockdown of ArfGAP1 reduce LRRK2 toxicity.\",\n      \"method\": \"In vitro GTPase assay; in vitro kinase assay; co-immunoprecipitation; dominant-negative expression; Drosophila in vivo toxicity assay; shRNA knockdown\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — replicated across two independent labs (PMID 22363216 and 22423108), multiple enzymatic assays and in vivo validation\",\n      \"pmids\": [\"22423108\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"ArfGAP1 promotes COPI vesicle formation by facilitating coatomer polymerization: ArfGAP1 increases coatomer-induced LUV deformation and, with cargo peptides, supports self-assembly of coatomer into spherical structures in the absence of membranes; ArfGAP1 overexpression in vivo induces vesicle accumulation while allowing normal COPI cargo trafficking.\",\n      \"method\": \"Electron microscopy of LUV deformation; coatomer self-assembly assay; in vivo overexpression with trafficking assay\",\n      \"journal\": \"Cellular logistics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple assays (EM, self-assembly, in vivo), single lab\",\n      \"pmids\": [\"22279613\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The non-catalytic C-terminal domain of ARFGAP1 (residues sufficient in GAP273 truncation) regulates actin cytoskeleton reorganization by inhibiting Rac1 activation upstream of Rac1; overexpression of constitutively active Rac1 or ARF6 suppresses the actin/spreading defects caused by this domain.\",\n      \"method\": \"Overexpression of truncation mutants; live-cell imaging; Rac1 activation assays; epistasis with constitutively active GTPases\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — genetic epistasis plus activation assays, multiple constructs, single lab\",\n      \"pmids\": [\"21483700\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"HCV NS5A interacts with ARFGAP1 via a conserved cluster of positively charged amino acids in NS5A; this interaction hijacks ARFGAP1 to remove the PI4P phosphatase Sac1 (a COPI cargo) from the HCV replication site, thereby maintaining high PI4P levels required for HCV RNA replication.\",\n      \"method\": \"Co-immunoprecipitation; mutational analysis of NS5A; siRNA knockdown of ARFGAP1; PI4P level measurement; HCV replication assay\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — co-IP plus functional knockdown and mutational analysis, single lab\",\n      \"pmids\": [\"24623438\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"ARFGAP1 associates transiently with lipid droplets upon oleate addition in hepatocytes; cAMP addition shifts ARFGAP1 from lipid droplets to the Golgi; overexpression and knockdown of ARFGAP1 affect lipid droplet formation.\",\n      \"method\": \"Fluorescence microscopy; subcellular fractionation; overexpression and siRNA knockdown with lipid droplet quantification\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — direct localization experiments with functional gain/loss, single lab\",\n      \"pmids\": [\"25397679\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"ArfGAP1 interacts with mTORC1 in the absence of amino acids and inhibits mTORC1 lysosomal localization and activation; the ALPS motifs of ArfGAP1 are required for this interaction and regulation of mTORC1 activity.\",\n      \"method\": \"Co-immunoprecipitation; lysosomal fractionation; mTORC1 activity assays; ALPS motif mutants; amino acid stimulation/deprivation\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP with functional mutants and lysosomal localization assay, single lab\",\n      \"pmids\": [\"33988249\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"ArfGAP1 directly interacts with GTP-bound Arl1 and exhibits GAP activity toward Arl1 in vitro; ArfGAP1 overexpression (but not GAP activity-deficient mutant) causes dissociation of Arl1 from the TGN; ArfGAP1 knockdown impairs endosome-to-TGN retrograde transport of Shiga toxin B-subunit, similar to constitutively active Arl1.\",\n      \"method\": \"In vitro GTPase assay; activity pull-down; GFP-Arl1 localization; Shiga toxin trafficking assay; siRNA knockdown\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro enzymatic assay with direct binding plus in vivo functional assays, single lab\",\n      \"pmids\": [\"33715220\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"ARFGAP1 promotes constitutive endocytosis of the glutamate transporter EAAT3 via its GAP activity using ARF6 as the substrate; a single phenylalanine residue (F508) in the EAAT3 C-terminus is required for ARFGAP1-promoted AP-2-dependent endocytosis; ARFGAP1 was identified as an EAAT3-interacting protein by mass spectrometry.\",\n      \"method\": \"Mass spectrometry; co-immunoprecipitation; GAP activity-deficient mutants; endocytosis assays; mutagenesis of F508\",\n      \"journal\": \"Frontiers in physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — MS identification plus functional mutant analysis and endocytosis assay, single lab\",\n      \"pmids\": [\"34040545\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ArfGAP1 controls actin cytoskeleton reorganization downstream of Arf1 and phospholipase D1 (PLD1) via the M3 muscarinic receptor pathway, restricting Mycobacterium tuberculosis entry into epithelial cells; ArfGAP1 silencing leads to uncontrolled actin reorganization and increased Mtb uptake, while infection by Shigella flexneri and Yersinia pseudotuberculosis is unaffected.\",\n      \"method\": \"siRNA knockdown; actin imaging; bacterial entry assays with multiple pathogens; genetic pathway analysis\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — loss-of-function with specific pathogen-specific phenotype and pathway placement, single lab\",\n      \"pmids\": [\"29141986\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Phosphatidic acid generated by phospholipase D2 (PLD2) is required for ArfGAP1 recruitment to Golgi membranes; inhibition or depletion of PLD2 prevents ArfGAP1 Golgi localization.\",\n      \"method\": \"PLD2 inhibition and siRNA depletion; fluorescence microscopy of ArfGAP1 localization\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — chemical inhibition and genetic depletion with direct localization readout, single lab\",\n      \"pmids\": [\"25354038\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"LRRK2 phosphorylates ArfGAP1 within its ALPS2 motif at residues Ser284, Thr291, and Thr292 in vitro; phospho-mimicking mutations at these sites impair ArfGAP1 Golgi localization, redirect it to the cytoplasm, increase its interaction with mitochondrial VDAC proteins, block Golgi-derived vesicle formation after ER stress, and impair neurite outgrowth inhibition; phospho-null mutations protect against G2019S LRRK2 neurotoxicity.\",\n      \"method\": \"In vitro kinase assay with site-directed mutagenesis; phospho-null and phospho-mimetic mutant analysis; subcellular localization; interactome analysis; primary neuron morphology assay\",\n      \"journal\": \"Frontiers in molecular neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro kinase assay with mutagenesis plus multiple functional readouts, single lab; peer-reviewed but very recent\",\n      \"pmids\": [\"42094986\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"In Drosophila border cells, ArfGAP1 is required to maintain receptor tyrosine kinases (guidance receptors) at the plasma membrane; loss of ArfGAP1 increases receptor levels in late endosomes, increases late endosome/lysosome number and size, reduces directional chemotaxis, and genetic interactions suggest ArfGAP1 acts on Lrrk to regulate receptor sorting.\",\n      \"method\": \"Drosophila genetics; fluorescence imaging of receptor localization; endosome/lysosome quantification; genetic interaction analysis\",\n      \"journal\": \"iScience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — in vivo loss-of-function with multiple cellular phenotypes and genetic epistasis, Drosophila model\",\n      \"pmids\": [\"37599820\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"ATG2A localizes to extra-Golgi ARFGAP1-positive puncta during autophagosome biogenesis; ARFGAP1 itself is dispensable for macroautophagy but marks membranes that associate with the autophagic machinery; when autophagosome formation or early secretory pathway is perturbed, ARFGAP1 and Rab1a accumulate at ectopic sites with autophagic components.\",\n      \"method\": \"Proximity labeling (BioID); fluorescence microscopy; siRNA depletion; co-immunoprecipitation\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 2–3 / Weak — proximity labeling and imaging, preprint, ARFGAP1 itself shown dispensable for autophagy\",\n      \"pmids\": [\"40196537\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"ARFGAP1 is a Golgi-localized GTPase-activating protein for Arf1 whose catalytic activity is coupled to membrane curvature through two ALPS (ArfGAP1 Lipid Packing Sensor) motifs that fold into amphipathic helices on highly curved membranes; it promotes both COPI vesicle formation and cargo sorting by functioning as a component of the COPI coat (binding cargo dilysine motifs and coatomer via C-terminal tryptophan-based motifs), regulates AP-2-dependent endocytosis through a separate coat-binding region, acts as a GTPase-activating protein for Arl1 at the TGN, inhibits mTORC1 lysosomal recruitment via its ALPS motifs under amino-acid-deplete conditions, controls actin cytoskeleton dynamics by antagonizing Rac1 activation, and is itself a substrate of LRRK2 kinase whose phosphorylation of the ALPS2 motif (Ser284/Thr291/Thr292) redirects ArfGAP1 from the Golgi to the cytoplasm and modulates its activity, Golgi vesicle formation, and LRRK2-linked neuronal toxicity.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ARFGAP1 is a GTPase-activating protein for Arf1 that times GTP hydrolysis during COPI vesicle biogenesis by sensing membrane curvature, thereby coupling the Arf1 GTPase cycle to the geometry of the budding vesicle [#0, #10]. Curvature sensing is achieved through two ALPS (ArfGAP1 Lipid Packing Sensor) motifs that are unstructured in solution but fold into amphipathic helices when inserting hydrophobic residues into loosely packed lipids of highly curved membranes; ALPS1 couples GAP activity to curvature and ALPS2 reinforces membrane binding and Golgi targeting [#1, #6, #10]. Unlike the coatomer-dependent ArfGAP2/3, ARFGAP1 binds membranes directly in a curvature-dependent manner, and its Golgi recruitment additionally depends on a hydrophobic stretch around Leu207/Trp211 and on phosphatidic acid generated by PLD2 [#7, #8, #25]. Within the COPI system ARFGAP1 functions intimately with the coat: it binds dilysine cargo motifs, promotes coatomer binding to cargo and coatomer polymerization, and undergoes coatomer- and Arf1-dependent cytosol/Golgi exchange, while cargo proteins such as p24\\u03b21 suppress its GAP activity to license vesicle formation [#2, #3, #5, #17]. Through distinct C-terminal tryptophan-based motifs ARFGAP1 engages clathrin adaptors and coatomer separately, allowing it to participate in both COPI transport and AP-2-dependent endocytosis [#12, #13]. Beyond Arf1, ARFGAP1 acts as a GAP toward Arl1 at the TGN to control retrograde transport and toward ARF6 during endocytosis of membrane transporters, and it restrains actin reorganization by inhibiting Rac1 activation [#22, #23, #18]. ARFGAP1 also intersects Parkinson's disease biology: it is a GAP for LRRK2 that enhances LRRK2 GTP hydrolysis and modulates LRRK2 kinase activity and neurotoxicity, and reciprocally it is a substrate of LRRK2, whose phosphorylation of the ALPS2 motif (Ser284/Thr291/Thr292) redirects ARFGAP1 from Golgi to cytoplasm and modulates Golgi vesicle formation and neurite outgrowth [#15, #16, #26]. Additional roles include inhibition of mTORC1 lysosomal recruitment via its ALPS motifs under amino-acid deprivation [#21].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Established whether ARFGAP1 acts merely as an uncoating enzyme or as an integral part of the COPI machinery, by showing it is present stoichiometrically and binds cargo directly.\",\n      \"evidence\": \"Reconstituted COPI vesicle formation from Golgi membranes with purified components plus dilysine-cargo binding assays\",\n      \"pmids\": [\"12379802\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry of ARFGAP1 on vesicles later disputed\", \"Did not resolve curvature dependence of GAP timing\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Answered how cargo loading is coordinated with the Arf1 GTPase timer, showing the p24\\u03b21 cytoplasmic domain binds ARFGAP1 and inhibits its GAP activity.\",\n      \"evidence\": \"Synthetic peptide binding and in vitro GTP hydrolysis assays on liposomes and Golgi membranes\",\n      \"pmids\": [\"11748249\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether other cargo classes regulate GAP activity similarly\", \"In vivo significance of inhibition during budding\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Resolved why GTP hydrolysis is timed to vesicle budding, demonstrating that ARFGAP1 catalytic activity is dramatically stimulated as bilayer curvature increases.\",\n      \"evidence\": \"Time-resolved in vitro GTP hydrolysis and COPI disassembly assays on size-controlled liposomes\",\n      \"pmids\": [\"14654841\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not yet identify the structural sensor of curvature\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Identified the molecular curvature sensor as the ALPS motif and showed Golgi localization depends on specific hydrophobic residues, while live-cell FRAP linked ARFGAP1 dynamics to coatomer and Arf1.\",\n      \"evidence\": \"Mutagenesis, CD, limited proteolysis, liposome binding, GFP localization, and FRAP in living cells\",\n      \"pmids\": [\"15944734\", \"16316994\", \"15795316\", \"15657398\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Number of curvature-sensing motifs not yet established\", \"How ALPS folding is regulated in vivo unknown\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Demonstrated ARFGAP1 carries a second ALPS motif (ALPS2) that strongly reinforces curvature-dependent membrane binding and Golgi targeting.\",\n      \"evidence\": \"Quantitative liposome binding, CD, and GFP localization with mutagenesis\",\n      \"pmids\": [\"17253781\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional division of labor between ALPS1 and ALPS2 in vivo\", \"Regulation of ALPS2 not addressed\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Distinguished ARFGAP1 from paralogs by showing it binds membranes directly in a curvature-dependent manner rather than via coatomer, and linked it to neuronal cargo (GAT-1).\",\n      \"evidence\": \"Comparative membrane-binding and GAP assays with purified ArfGAP1/2/3; co-IP and siRNA with axonal targeting readout\",\n      \"pmids\": [\"19015319\", \"19020038\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of GAT-1 sorting by ARFGAP1 incomplete\", \"Generality of cargo handling\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Provided spatial proof of curvature-restricted activity, showing ALPS motifs bind only positively curved tubes and generate an Arf1 activity gradient.\",\n      \"evidence\": \"Membrane tube pulling with optical tweezers and molecular motors plus fluorescence microscopy\",\n      \"pmids\": [\"19927117\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether such gradients form on native Golgi\", \"Coupling to coat assembly in cells\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Challenged the stoichiometric-coat model by showing catalytic amounts of ARFGAP1 reduce COPI vesicle yield, favoring an uncoating role.\",\n      \"evidence\": \"Defined reconstitution with titrated ArfGAP1 and vesicle quantification\",\n      \"pmids\": [\"19055691\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Directly contradicts other reconstitution studies\", \"Single-lab result not independently reconciled\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Mapped how ARFGAP1 engages two coat systems through separate C-terminal motifs, enabling roles in both COPI transport and AP-2-dependent endocytosis, and clarified its action on coatomer polymerization.\",\n      \"evidence\": \"GST pulldowns, peptide competition, co-IP, selective disruption mutants and transport/EM assays\",\n      \"pmids\": [\"20211604\", \"21499258\", \"22279613\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How dual coat engagement is temporally segregated\", \"Whether AP-1 vs AP-2 binding is regulated\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Established a reciprocal enzymatic relationship with the Parkinson's kinase LRRK2 — ARFGAP1 as a GAP for LRRK2 and a substrate that modulates LRRK2 toxicity.\",\n      \"evidence\": \"In vitro GTPase and kinase assays, co-IP in cells and brain, siRNA/dominant-negative and Drosophila toxicity readouts\",\n      \"pmids\": [\"22363216\", \"22423108\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Phosphosites on ARFGAP1 not yet mapped\", \"Physiological context of LRRK2 regulation\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Extended ARFGAP1 function to lipid droplet biology, viral hijacking, and PLD2-dependent Golgi recruitment.\",\n      \"evidence\": \"Microscopy, fractionation, co-IP, siRNA, PI4P measurement, and PLD2 inhibition/depletion\",\n      \"pmids\": [\"25397679\", \"24623438\", \"25354038\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of lipid droplet association unclear\", \"Single-lab observations for each role\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Placed ARFGAP1 in actin-cytoskeleton control downstream of Arf1/PLD1, restraining Rac1 and limiting bacterial entry.\",\n      \"evidence\": \"siRNA, actin imaging, Rac1 activation assays and pathogen entry assays with epistasis\",\n      \"pmids\": [\"29141986\", \"21483700\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular target in Rac1 inhibition not defined\", \"Whether catalytic vs non-catalytic domain mediates each effect\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Broadened the GAP repertoire to Arl1 at the TGN and ARF6 in endocytosis, and revealed ALPS-dependent inhibition of mTORC1 lysosomal recruitment under amino-acid deprivation.\",\n      \"evidence\": \"In vitro GTPase/activity assays, GFP-Arl1 and EAAT3 endocytosis assays, co-IP, lysosomal fractionation and ALPS mutants\",\n      \"pmids\": [\"33715220\", \"34040545\", \"33988249\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How substrate selection among Arf1/Arl1/ARF6 is achieved\", \"Mechanism of mTORC1 inhibition single-lab\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Defined the LRRK2 phosphorylation sites on the ALPS2 motif and showed phosphorylation redirects ARFGAP1 from Golgi to cytoplasm, altering vesicle formation and neurotoxicity.\",\n      \"evidence\": \"In vitro kinase assays with site-directed mutagenesis, phospho-mimetic/null mutants, localization, interactome and primary neuron morphology\",\n      \"pmids\": [\"42094986\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo confirmation of phosphoregulation\", \"Functional meaning of VDAC interaction\", \"Single-lab and very recent\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How ARFGAP1's many context-specific roles — COPI/AP coat cycling, Arl1/ARF6 GAP activity, mTORC1, actin, and LRRK2 crosstalk — are integrated and regulated within a single cell remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Unified model of substrate/pathway selection lacking\", \"Stoichiometric-coat versus uncoating controversy unsettled\", \"Physiological relevance of LRRK2 phosphoregulation in vivo unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 22, 23, 15, 16]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [1, 6, 10, 25]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [15, 16, 26]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [2, 12, 13]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [6, 7, 25, 5]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [5, 26]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [2, 9, 17]},\n      {\"term_id\": \"GO:0005811\", \"supporting_discovery_ids\": [20]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [0, 2, 4, 13, 22]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [14, 22, 23]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [15, 16, 19, 24, 26]}\n    ],\n    \"complexes\": [\"COPI coat\"],\n    \"partners\": [\"ARF1\", \"ARL1\", \"ARF6\", \"LRRK2\", \"COPB1\", \"AP-2\", \"AP-1\", \"TMED2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}