{"gene":"MON2","run_date":"2026-06-10T02:59:50","timeline":{"discoveries":[{"year":2005,"finding":"Yeast Mon2 localizes to the trans-Golgi and forms a complex with Dop1 (DOPEY orthologue); deletion of Mon2 causes mislocalization of Dop1 from the Golgi and defects in endosome-to-Golgi cycling, establishing Mon2 as a scaffold that recruits the Golgi-localized pool of Dop1.","method":"Genetic deletion, co-immunoprecipitation, subcellular localization (fluorescence microscopy), yeast genetics","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal interaction data, genetic epistasis (deletion phenotype), subcellular localization, and functional transport assays in one study","pmids":["16301316"],"is_preprint":false},{"year":2011,"finding":"Drosophila Mon2 acts downstream of Oskar to remodel cortical actin and anchor the germ plasm; Mon2 interacts with actin nucleators Cappuccino and Spire and promotes accumulation of Rho1 at the oocyte posterior, coupling Osk-induced endocytic activity to F-actin projection formation.","method":"Co-immunoprecipitation (Mon2 with Capu and Spire), genetic epistasis (loss-of-function), immunofluorescence localization, live imaging","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic epistasis combined with co-IP binding partners and localization readouts in a single focused study","pmids":["21610029"],"is_preprint":false},{"year":2011,"finding":"Human Mon2 (hMon2) is required for efficient production of infectious HIV-1 virions; depletion of hMon2 in human cells reduces HIV-1 Gag-induced virus-like particle release, consistent with its role in protein trafficking.","method":"RNAi knockdown in human cells, VLP release assay, yeast genetic screen for Gag plasma-membrane targeting","journal":"Journal of virology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — clean KD with defined cellular phenotype (virion release) in a single lab study","pmids":["21450827"],"is_preprint":false},{"year":2012,"finding":"In yeast, MON2 functions as a negative regulator of Arl1-GTP (the GTP-restricted allele ARL1[Q72L]); synthetic lethality and allele-specific suppression establish a genetic epistasis relationship between MON2 and ARL1 in membrane trafficking.","method":"Site-directed mutagenesis of ARL1, synthetic lethality analysis, CPY secretion assay, genetic epistasis","journal":"FEMS yeast research","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — genetic epistasis with allele-specific suppression in a single lab; no biochemical interaction data","pmids":["22594927"],"is_preprint":false},{"year":2018,"finding":"Human MON2 assembles an evolutionarily conserved endosome-associated complex with DOPEY2 and the putative aminophospholipid translocase ATP9A; SNX3 associates with this MON2:DOPEY2:ATP9A complex on endosomes to mediate SNX3-retromer-dependent Wntless endosome-to-Golgi transport and Wnt secretion. In C. elegans, loss of Ce-mon-2 phenocopies loss of SNX3-retromer function, causing lysosomal degradation of Wntless and a Wnt morphogenetic phenotype.","method":"Co-immunoprecipitation, mass spectrometry, C. elegans RNAi knockdown (genetic epistasis), fluorescence microscopy, ATPase-dead mutant overexpression","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, in vivo genetic epistasis, multiple orthogonal methods across human and C. elegans, replicated in two organisms","pmids":["30213940"],"is_preprint":false},{"year":2019,"finding":"Dopey1 and Mon2 form a complex that localizes to the Golgi, endolysosome, and ER exit sites; Mon2 binding to phosphatidic acid and Dopey1 binding to phosphatidylinositol-4-phosphate are required for Golgi localization; the N-terminus of Dopey1 recruits kinesin-1, making the Dopey1-Mon2 complex a dual-lipid-regulated cargo adaptor that drives centrifugally biased bidirectional transport of secretory and endocytic organelles along microtubules.","method":"Co-immunoprecipitation, lipid-binding assay, subcellular fractionation/live imaging, kinesin-1 pulldown, transport assay","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP, lipid-binding biochemistry, and functional transport readouts combined in a single focused study","pmids":["31324769"],"is_preprint":false},{"year":2020,"finding":"MON2 drives the separation of recycling endosomes (RE) from early endosomes (EE) and is required for the tubular RE network; MON2-knockout impairs segregation of RE from EE, accumulates RE at the perinuclear region, and blocks retrograde transport of Wntless through RE before its delivery to the Golgi. DOPEY2-knockout causes perinuclear RE accumulation, and membrane-bound DOPEY2 is recruited to RE in a MON2-dependent manner and binds kinesin and dynein/dynactin motors.","method":"MON2-knockout and DOPEY2-knockout (CRISPR/genetics), live imaging, co-localization, transferrin receptor recycling assay, Wntless transport assay","journal":"Cell structure and function","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic KO with specific organelle and cargo phenotypes, multiple orthogonal transport assays, live imaging in a single study","pmids":["32404555"],"is_preprint":false},{"year":2021,"finding":"Mammalian MON2 physically interacts with GABARAPL2 and this interaction increases autophagic flux; in C. elegans, MON-2 activates the GABARAP orthologue LGG-1 to upregulate autophagy, contributing to longevity of mitochondrial respiration mutants. MON2 translocates from the Golgi to endosomes under starvation conditions.","method":"Co-immunoprecipitation (MON2-GABARAPL2), autophagic flux assays in mammalian cells, C. elegans loss-of-function (RNAi/mutants), proteomics, live imaging of MON2 translocation","journal":"Science advances","confidence":"High","confidence_rationale":"Tier 2 / Strong — Co-IP binding partner identified, autophagic flux measured in mammalian cells, genetic epistasis in C. elegans; independently supported by a companion commentary (PMID:35188063)","pmids":["34860542","35188063"],"is_preprint":false}],"current_model":"MON2 is an evolutionarily conserved Golgi/endosomal scaffold protein that (1) recruits DOPEY (Dop1/DOPEY1/DOPEY2) to the trans-Golgi via a phosphatidic acid-binding interaction, (2) assembles with DOPEY2 and the flippase ATP9A to facilitate SNX3-retromer-dependent endosome-to-Golgi transport of cargoes such as Wntless, (3) drives separation of recycling endosomes from early endosomes to support retrograde trafficking, (4) links membrane carriers to kinesin-1-mediated microtubule transport through the Dopey1–MON2 dual-lipid-regulated adaptor complex, (5) negatively regulates Arl1-GTP on Golgi membranes, (6) couples endocytic activity to actin remodeling via interactions with Cappuccino, Spire, and Rho1 in Drosophila, (7) is required for efficient HIV-1 virion production in human cells, and (8) promotes autophagy by physically interacting with and activating GABARAPL2/LGG-1 upon translocation from the Golgi to endosomes under starvation conditions."},"narrative":{"mechanistic_narrative":"MON2 is an evolutionarily conserved Golgi- and endosome-associated scaffold protein that organizes retrograde and recycling membrane traffic by coupling cargo carriers to lipid cues and cytoskeletal motors [PMID:16301316, PMID:31324769]. Its core activity is to recruit a DOPEY-family partner: yeast Mon2 binds Dop1 and is required for its Golgi localization and for normal endosome-to-Golgi cycling [PMID:16301316], and in mammals MON2 binds phosphatidic acid while its partner Dopey1 binds phosphatidylinositol-4-phosphate, together forming a dual-lipid-regulated adaptor whose Dopey1 N-terminus engages kinesin-1 to drive microtubule-based transport of secretory and endocytic organelles [PMID:31324769]. On endosomes, MON2 assembles with DOPEY2 and the putative aminophospholipid translocase ATP9A into a complex that supports SNX3-retromer-dependent endosome-to-Golgi transport of Wntless and Wnt secretion, with loss of MON2 phenocopying retromer failure and diverting Wntless to lysosomal degradation [PMID:30213940]. MON2 further drives the segregation of recycling endosomes from early endosomes and is required for the tubular recycling network and for retrograde Wntless trafficking, recruiting membrane-bound DOPEY2 that engages both kinesin and dynein/dynactin motors [PMID:32404555]. In yeast it acts as a negative regulator of Arl1-GTP at the Golgi [PMID:22594927]. Beyond core trafficking, MON2 couples endocytic activity to actin remodeling in the Drosophila oocyte through interactions with Cappuccino, Spire, and Rho1 [PMID:21610029], is required for efficient HIV-1 virion production [PMID:21450827], and promotes autophagy by translocating from Golgi to endosomes under starvation and physically activating GABARAPL2/LGG-1 to increase autophagic flux [PMID:34860542, PMID:35188063].","teleology":[{"year":2005,"claim":"Established MON2 as a Golgi scaffold by showing it recruits the DOPEY orthologue Dop1 and is needed for endosome-to-Golgi cycling, defining the core molecular partnership that anchors all later work.","evidence":"Genetic deletion, co-immunoprecipitation, and fluorescence localization in yeast","pmids":["16301316"],"confidence":"High","gaps":["Mechanism by which Mon2 targets to the trans-Golgi not defined","No biochemical reconstitution of the Mon2-Dop1 interaction","Direct cargo not identified at this stage"]},{"year":2011,"claim":"Extended MON2 function beyond canonical trafficking by linking it to actin remodeling, showing it interacts with nucleators Cappuccino and Spire and Rho1 to couple Oskar-induced endocytosis to cortical F-actin in the oocyte.","evidence":"Co-immunoprecipitation, genetic epistasis, and live imaging in Drosophila","pmids":["21610029"],"confidence":"High","gaps":["Whether actin coupling is conserved outside Drosophila germ plasm unknown","Direct vs indirect nature of Mon2-Capu/Spire binding not resolved"]},{"year":2011,"claim":"Connected MON2 trafficking function to a disease-relevant process by showing human MON2 is required for efficient HIV-1 virion production.","evidence":"RNAi knockdown with VLP release assay in human cells plus yeast Gag-targeting screen","pmids":["21450827"],"confidence":"Medium","gaps":["Step in Gag trafficking/assembly that requires MON2 not pinpointed","Single-lab study without orthogonal validation of specificity"]},{"year":2012,"claim":"Positioned MON2 within Golgi GTPase regulation by establishing it as a genetic negative regulator of Arl1-GTP.","evidence":"ARL1 allele-specific suppression, synthetic lethality, and CPY secretion assay in yeast","pmids":["22594927"],"confidence":"Medium","gaps":["No biochemical interaction between Mon2 and Arl1 demonstrated","Mechanism of negative regulation (GAP-like vs indirect) unknown"]},{"year":2018,"claim":"Defined the endosomal effector complex by showing MON2 assembles with DOPEY2 and the flippase ATP9A and works with SNX3-retromer to recycle Wntless from endosome to Golgi, identifying a concrete cargo and pathway.","evidence":"Co-IP, mass spectrometry, C. elegans RNAi epistasis, and ATPase-dead mutant analysis across human and worm","pmids":["30213940"],"confidence":"High","gaps":["Catalytic role of ATP9A flippase activity in the complex not directly resolved","How SNX3-retromer engages the complex structurally unknown"]},{"year":2019,"claim":"Provided the biophysical logic of MON2 carrier function by showing the Dopey1-MON2 complex reads two lipids (PA and PI4P) and recruits kinesin-1, making it a dual-lipid-regulated cargo adaptor for microtubule transport.","evidence":"Co-IP, lipid-binding assays, kinesin-1 pulldown, and transport/live-imaging assays","pmids":["31324769"],"confidence":"High","gaps":["Structure of the adaptor-motor interface not determined","How lipid binding is regulated in time/space unknown"]},{"year":2020,"claim":"Resolved the organelle-level role by showing MON2 drives separation of recycling from early endosomes and is required for the tubular recycling network and retrograde Wntless transport, with DOPEY2 recruited MON2-dependently to engage both kinesin and dynein/dynactin.","evidence":"CRISPR knockouts, live imaging, colocalization, and transferrin/Wntless transport assays","pmids":["32404555"],"confidence":"High","gaps":["Molecular trigger that initiates RE-EE segregation not defined","How bidirectional motor engagement is balanced unknown"]},{"year":2021,"claim":"Linked MON2 to autophagy by showing starvation-induced Golgi-to-endosome translocation lets it bind and activate GABARAPL2/LGG-1 to raise autophagic flux and support longevity in mitochondrial mutants.","evidence":"Co-IP, autophagic flux assays in mammalian cells, C. elegans genetics, proteomics, and translocation imaging","pmids":["34860542","35188063"],"confidence":"High","gaps":["Signal driving starvation translocation not identified","Mechanism by which MON2 activates GABARAPL2 not resolved"]},{"year":null,"claim":"How MON2's distinct activities — retrograde recycling, motor-coupled transport, Arl1 regulation, actin remodeling, and autophagy — are integrated and switched within one protein remains unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No structural model of MON2 or its complexes","Regulatory logic governing Golgi-vs-endosome partitioning unknown","Whether functions are sequential or parallel not established"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,5,6]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[5]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[3,7]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[0,5,7]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[4,6,7]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[5]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[0,4,6]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[4,5,6]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[7]}],"complexes":["MON2:DOPEY2:ATP9A endosomal complex","Dopey1-MON2 cargo adaptor complex"],"partners":["DOPEY1","DOPEY2","ATP9A","SNX3","GABARAPL2","CAPPUCCINO","SPIRE","RHO1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q7Z3U7","full_name":"Protein MON2 homolog","aliases":["Protein SF21"],"length_aa":1717,"mass_kda":190.4,"function":"Plays a role in regulating membrane trafficking of cargo proteins. Together with ATP9A and DOP1B, regulates SNX3 retromer-mediated endosomal sorting of WLS away from lysosomal degradation","subcellular_location":"Early endosome membrane","url":"https://www.uniprot.org/uniprotkb/Q7Z3U7/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MON2","classification":"Not Classified","n_dependent_lines":178,"n_total_lines":1208,"dependency_fraction":0.14735099337748345},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"SPTLC1","stoichiometry":0.2},{"gene":"TAF12","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/MON2","total_profiled":1310},"omim":[{"mim_id":"617574","title":"ICHTHYOSIS, CONGENITAL, AUTOSOMAL RECESSIVE 13; ARCI13","url":"https://www.omim.org/entry/617574"},{"mim_id":"616823","title":"DOP1 LEUCINE ZIPPER-LIKE PROTEIN A; DOP1A","url":"https://www.omim.org/entry/616823"},{"mim_id":"616822","title":"MON2, REGULATOR OF ENDOSOME-TO-GOLGI TRAFFICKING; MON2","url":"https://www.omim.org/entry/616822"},{"mim_id":"615627","title":"BRI3-BINDING PROTEIN; BRI3BP","url":"https://www.omim.org/entry/615627"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Nucleoli fibrillar center","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/MON2"},"hgnc":{"alias_symbol":["KIAA1040"],"prev_symbol":[]},"alphafold":{"accession":"Q7Z3U7","domains":[{"cath_id":"-","chopping":"2-136","consensus_level":"medium","plddt":84.0097,"start":2,"end":136},{"cath_id":"-","chopping":"140-186_210-285","consensus_level":"medium","plddt":86.9802,"start":140,"end":285},{"cath_id":"-","chopping":"286-291_305-405_447-492","consensus_level":"medium","plddt":83.9852,"start":286,"end":492},{"cath_id":"-","chopping":"621-626_655-850","consensus_level":"medium","plddt":84.0013,"start":621,"end":850},{"cath_id":"1.20.58","chopping":"1061-1087_1108-1175","consensus_level":"medium","plddt":87.0753,"start":1061,"end":1175},{"cath_id":"1.25.40","chopping":"1236-1257_1267-1383_1402-1425","consensus_level":"medium","plddt":83.1127,"start":1236,"end":1425}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q7Z3U7","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q7Z3U7-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q7Z3U7-F1-predicted_aligned_error_v6.png","plddt_mean":77.94},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MON2","jax_strain_url":"https://www.jax.org/strain/search?query=MON2"},"sequence":{"accession":"Q7Z3U7","fasta_url":"https://rest.uniprot.org/uniprotkb/Q7Z3U7.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q7Z3U7/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q7Z3U7"}},"corpus_meta":[{"pmid":"30213940","id":"PMC_30213940","title":"SNX3-retromer requires an evolutionary conserved MON2:DOPEY2:ATP9A complex to mediate Wntless sorting and Wnt secretion.","date":"2018","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/30213940","citation_count":71,"is_preprint":false},{"pmid":"16301316","id":"PMC_16301316","title":"Mon2, a relative of large Arf exchange factors, recruits Dop1 to the Golgi apparatus.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16301316","citation_count":34,"is_preprint":false},{"pmid":"21610029","id":"PMC_21610029","title":"Drosophila Mon2 couples Oskar-induced endocytosis with actin remodeling for cortical anchorage of the germ plasm.","date":"2011","source":"Development (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/21610029","citation_count":34,"is_preprint":false},{"pmid":"31324769","id":"PMC_31324769","title":"Dopey1-Mon2 complex binds to dual-lipids and recruits kinesin-1 for membrane trafficking.","date":"2019","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/31324769","citation_count":29,"is_preprint":false},{"pmid":"34860542","id":"PMC_34860542","title":"MON-2, a Golgi protein, mediates autophagy-dependent longevity in Caenorhabditis elegans.","date":"2021","source":"Science advances","url":"https://pubmed.ncbi.nlm.nih.gov/34860542","citation_count":19,"is_preprint":false},{"pmid":"21450827","id":"PMC_21450827","title":"The cellular factors Vps18 and Mon2 are required for efficient production of infectious HIV-1 particles.","date":"2011","source":"Journal of virology","url":"https://pubmed.ncbi.nlm.nih.gov/21450827","citation_count":17,"is_preprint":false},{"pmid":"32404555","id":"PMC_32404555","title":"MON2 Guides Wntless Transport to the Golgi through Recycling Endosomes.","date":"2020","source":"Cell structure and function","url":"https://pubmed.ncbi.nlm.nih.gov/32404555","citation_count":14,"is_preprint":false},{"pmid":"32413468","id":"PMC_32413468","title":"Mon2-monocytes and increased CD-11b expression before transcatheter aortic valve implantation are associated with earlier death.","date":"2020","source":"International journal of cardiology","url":"https://pubmed.ncbi.nlm.nih.gov/32413468","citation_count":12,"is_preprint":false},{"pmid":"22594927","id":"PMC_22594927","title":"Mon2 is a negative regulator of the monomeric G protein, Arl1.","date":"2012","source":"FEMS yeast research","url":"https://pubmed.ncbi.nlm.nih.gov/22594927","citation_count":5,"is_preprint":false},{"pmid":"39628352","id":"PMC_39628352","title":"Targeted RNA sequencing in diagnostically challenging head and neck carcinomas identifies novel MON2::STAT6, NFATC2::NUTM2B, POC5::RAF1, and NSD3::NCOA2 gene fusions.","date":"2024","source":"Histopathology","url":"https://pubmed.ncbi.nlm.nih.gov/39628352","citation_count":4,"is_preprint":false},{"pmid":"32572912","id":"PMC_32572912","title":"MicroRNA-133a-5p inhibiting metastatic capacity of renal clear cell carcinoma through regulating MON2.","date":"2020","source":"European review for medical and pharmacological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/32572912","citation_count":4,"is_preprint":false},{"pmid":"35188063","id":"PMC_35188063","title":"MON-2, a Golgi protein, promotes longevity by upregulating autophagy through mediating inter-organelle communications.","date":"2022","source":"Autophagy","url":"https://pubmed.ncbi.nlm.nih.gov/35188063","citation_count":4,"is_preprint":false},{"pmid":"34236108","id":"PMC_34236108","title":"Novel MLL/KMT2A-MON2 fusion in a child with therapy-related acute myeloid leukemia after treatment for acute promyelocytic leukemia.","date":"2021","source":"Molecular carcinogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/34236108","citation_count":3,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7966,"output_tokens":2363,"usd":0.029671,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9368,"output_tokens":3225,"usd":0.063732,"stage2_stop_reason":"end_turn"},"total_usd":0.093403,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2005,\n      \"finding\": \"Yeast Mon2 localizes to the trans-Golgi and forms a complex with Dop1 (DOPEY orthologue); deletion of Mon2 causes mislocalization of Dop1 from the Golgi and defects in endosome-to-Golgi cycling, establishing Mon2 as a scaffold that recruits the Golgi-localized pool of Dop1.\",\n      \"method\": \"Genetic deletion, co-immunoprecipitation, subcellular localization (fluorescence microscopy), yeast genetics\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal interaction data, genetic epistasis (deletion phenotype), subcellular localization, and functional transport assays in one study\",\n      \"pmids\": [\"16301316\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Drosophila Mon2 acts downstream of Oskar to remodel cortical actin and anchor the germ plasm; Mon2 interacts with actin nucleators Cappuccino and Spire and promotes accumulation of Rho1 at the oocyte posterior, coupling Osk-induced endocytic activity to F-actin projection formation.\",\n      \"method\": \"Co-immunoprecipitation (Mon2 with Capu and Spire), genetic epistasis (loss-of-function), immunofluorescence localization, live imaging\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis combined with co-IP binding partners and localization readouts in a single focused study\",\n      \"pmids\": [\"21610029\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Human Mon2 (hMon2) is required for efficient production of infectious HIV-1 virions; depletion of hMon2 in human cells reduces HIV-1 Gag-induced virus-like particle release, consistent with its role in protein trafficking.\",\n      \"method\": \"RNAi knockdown in human cells, VLP release assay, yeast genetic screen for Gag plasma-membrane targeting\",\n      \"journal\": \"Journal of virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — clean KD with defined cellular phenotype (virion release) in a single lab study\",\n      \"pmids\": [\"21450827\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"In yeast, MON2 functions as a negative regulator of Arl1-GTP (the GTP-restricted allele ARL1[Q72L]); synthetic lethality and allele-specific suppression establish a genetic epistasis relationship between MON2 and ARL1 in membrane trafficking.\",\n      \"method\": \"Site-directed mutagenesis of ARL1, synthetic lethality analysis, CPY secretion assay, genetic epistasis\",\n      \"journal\": \"FEMS yeast research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — genetic epistasis with allele-specific suppression in a single lab; no biochemical interaction data\",\n      \"pmids\": [\"22594927\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Human MON2 assembles an evolutionarily conserved endosome-associated complex with DOPEY2 and the putative aminophospholipid translocase ATP9A; SNX3 associates with this MON2:DOPEY2:ATP9A complex on endosomes to mediate SNX3-retromer-dependent Wntless endosome-to-Golgi transport and Wnt secretion. In C. elegans, loss of Ce-mon-2 phenocopies loss of SNX3-retromer function, causing lysosomal degradation of Wntless and a Wnt morphogenetic phenotype.\",\n      \"method\": \"Co-immunoprecipitation, mass spectrometry, C. elegans RNAi knockdown (genetic epistasis), fluorescence microscopy, ATPase-dead mutant overexpression\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, in vivo genetic epistasis, multiple orthogonal methods across human and C. elegans, replicated in two organisms\",\n      \"pmids\": [\"30213940\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Dopey1 and Mon2 form a complex that localizes to the Golgi, endolysosome, and ER exit sites; Mon2 binding to phosphatidic acid and Dopey1 binding to phosphatidylinositol-4-phosphate are required for Golgi localization; the N-terminus of Dopey1 recruits kinesin-1, making the Dopey1-Mon2 complex a dual-lipid-regulated cargo adaptor that drives centrifugally biased bidirectional transport of secretory and endocytic organelles along microtubules.\",\n      \"method\": \"Co-immunoprecipitation, lipid-binding assay, subcellular fractionation/live imaging, kinesin-1 pulldown, transport assay\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP, lipid-binding biochemistry, and functional transport readouts combined in a single focused study\",\n      \"pmids\": [\"31324769\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MON2 drives the separation of recycling endosomes (RE) from early endosomes (EE) and is required for the tubular RE network; MON2-knockout impairs segregation of RE from EE, accumulates RE at the perinuclear region, and blocks retrograde transport of Wntless through RE before its delivery to the Golgi. DOPEY2-knockout causes perinuclear RE accumulation, and membrane-bound DOPEY2 is recruited to RE in a MON2-dependent manner and binds kinesin and dynein/dynactin motors.\",\n      \"method\": \"MON2-knockout and DOPEY2-knockout (CRISPR/genetics), live imaging, co-localization, transferrin receptor recycling assay, Wntless transport assay\",\n      \"journal\": \"Cell structure and function\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with specific organelle and cargo phenotypes, multiple orthogonal transport assays, live imaging in a single study\",\n      \"pmids\": [\"32404555\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Mammalian MON2 physically interacts with GABARAPL2 and this interaction increases autophagic flux; in C. elegans, MON-2 activates the GABARAP orthologue LGG-1 to upregulate autophagy, contributing to longevity of mitochondrial respiration mutants. MON2 translocates from the Golgi to endosomes under starvation conditions.\",\n      \"method\": \"Co-immunoprecipitation (MON2-GABARAPL2), autophagic flux assays in mammalian cells, C. elegans loss-of-function (RNAi/mutants), proteomics, live imaging of MON2 translocation\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — Co-IP binding partner identified, autophagic flux measured in mammalian cells, genetic epistasis in C. elegans; independently supported by a companion commentary (PMID:35188063)\",\n      \"pmids\": [\"34860542\", \"35188063\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MON2 is an evolutionarily conserved Golgi/endosomal scaffold protein that (1) recruits DOPEY (Dop1/DOPEY1/DOPEY2) to the trans-Golgi via a phosphatidic acid-binding interaction, (2) assembles with DOPEY2 and the flippase ATP9A to facilitate SNX3-retromer-dependent endosome-to-Golgi transport of cargoes such as Wntless, (3) drives separation of recycling endosomes from early endosomes to support retrograde trafficking, (4) links membrane carriers to kinesin-1-mediated microtubule transport through the Dopey1–MON2 dual-lipid-regulated adaptor complex, (5) negatively regulates Arl1-GTP on Golgi membranes, (6) couples endocytic activity to actin remodeling via interactions with Cappuccino, Spire, and Rho1 in Drosophila, (7) is required for efficient HIV-1 virion production in human cells, and (8) promotes autophagy by physically interacting with and activating GABARAPL2/LGG-1 upon translocation from the Golgi to endosomes under starvation conditions.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MON2 is an evolutionarily conserved Golgi- and endosome-associated scaffold protein that organizes retrograde and recycling membrane traffic by coupling cargo carriers to lipid cues and cytoskeletal motors [#0, #5]. Its core activity is to recruit a DOPEY-family partner: yeast Mon2 binds Dop1 and is required for its Golgi localization and for normal endosome-to-Golgi cycling [#0], and in mammals MON2 binds phosphatidic acid while its partner Dopey1 binds phosphatidylinositol-4-phosphate, together forming a dual-lipid-regulated adaptor whose Dopey1 N-terminus engages kinesin-1 to drive microtubule-based transport of secretory and endocytic organelles [#5]. On endosomes, MON2 assembles with DOPEY2 and the putative aminophospholipid translocase ATP9A into a complex that supports SNX3-retromer-dependent endosome-to-Golgi transport of Wntless and Wnt secretion, with loss of MON2 phenocopying retromer failure and diverting Wntless to lysosomal degradation [#4]. MON2 further drives the segregation of recycling endosomes from early endosomes and is required for the tubular recycling network and for retrograde Wntless trafficking, recruiting membrane-bound DOPEY2 that engages both kinesin and dynein/dynactin motors [#6]. In yeast it acts as a negative regulator of Arl1-GTP at the Golgi [#3]. Beyond core trafficking, MON2 couples endocytic activity to actin remodeling in the Drosophila oocyte through interactions with Cappuccino, Spire, and Rho1 [#1], is required for efficient HIV-1 virion production [#2], and promotes autophagy by translocating from Golgi to endosomes under starvation and physically activating GABARAPL2/LGG-1 to increase autophagic flux [#7].\",\n  \"teleology\": [\n    {\n      \"year\": 2005,\n      \"claim\": \"Established MON2 as a Golgi scaffold by showing it recruits the DOPEY orthologue Dop1 and is needed for endosome-to-Golgi cycling, defining the core molecular partnership that anchors all later work.\",\n      \"evidence\": \"Genetic deletion, co-immunoprecipitation, and fluorescence localization in yeast\",\n      \"pmids\": [\"16301316\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which Mon2 targets to the trans-Golgi not defined\", \"No biochemical reconstitution of the Mon2-Dop1 interaction\", \"Direct cargo not identified at this stage\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Extended MON2 function beyond canonical trafficking by linking it to actin remodeling, showing it interacts with nucleators Cappuccino and Spire and Rho1 to couple Oskar-induced endocytosis to cortical F-actin in the oocyte.\",\n      \"evidence\": \"Co-immunoprecipitation, genetic epistasis, and live imaging in Drosophila\",\n      \"pmids\": [\"21610029\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether actin coupling is conserved outside Drosophila germ plasm unknown\", \"Direct vs indirect nature of Mon2-Capu/Spire binding not resolved\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Connected MON2 trafficking function to a disease-relevant process by showing human MON2 is required for efficient HIV-1 virion production.\",\n      \"evidence\": \"RNAi knockdown with VLP release assay in human cells plus yeast Gag-targeting screen\",\n      \"pmids\": [\"21450827\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Step in Gag trafficking/assembly that requires MON2 not pinpointed\", \"Single-lab study without orthogonal validation of specificity\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Positioned MON2 within Golgi GTPase regulation by establishing it as a genetic negative regulator of Arl1-GTP.\",\n      \"evidence\": \"ARL1 allele-specific suppression, synthetic lethality, and CPY secretion assay in yeast\",\n      \"pmids\": [\"22594927\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No biochemical interaction between Mon2 and Arl1 demonstrated\", \"Mechanism of negative regulation (GAP-like vs indirect) unknown\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined the endosomal effector complex by showing MON2 assembles with DOPEY2 and the flippase ATP9A and works with SNX3-retromer to recycle Wntless from endosome to Golgi, identifying a concrete cargo and pathway.\",\n      \"evidence\": \"Co-IP, mass spectrometry, C. elegans RNAi epistasis, and ATPase-dead mutant analysis across human and worm\",\n      \"pmids\": [\"30213940\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Catalytic role of ATP9A flippase activity in the complex not directly resolved\", \"How SNX3-retromer engages the complex structurally unknown\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Provided the biophysical logic of MON2 carrier function by showing the Dopey1-MON2 complex reads two lipids (PA and PI4P) and recruits kinesin-1, making it a dual-lipid-regulated cargo adaptor for microtubule transport.\",\n      \"evidence\": \"Co-IP, lipid-binding assays, kinesin-1 pulldown, and transport/live-imaging assays\",\n      \"pmids\": [\"31324769\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structure of the adaptor-motor interface not determined\", \"How lipid binding is regulated in time/space unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Resolved the organelle-level role by showing MON2 drives separation of recycling from early endosomes and is required for the tubular recycling network and retrograde Wntless transport, with DOPEY2 recruited MON2-dependently to engage both kinesin and dynein/dynactin.\",\n      \"evidence\": \"CRISPR knockouts, live imaging, colocalization, and transferrin/Wntless transport assays\",\n      \"pmids\": [\"32404555\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular trigger that initiates RE-EE segregation not defined\", \"How bidirectional motor engagement is balanced unknown\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Linked MON2 to autophagy by showing starvation-induced Golgi-to-endosome translocation lets it bind and activate GABARAPL2/LGG-1 to raise autophagic flux and support longevity in mitochondrial mutants.\",\n      \"evidence\": \"Co-IP, autophagic flux assays in mammalian cells, C. elegans genetics, proteomics, and translocation imaging\",\n      \"pmids\": [\"34860542\", \"35188063\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Signal driving starvation translocation not identified\", \"Mechanism by which MON2 activates GABARAPL2 not resolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How MON2's distinct activities — retrograde recycling, motor-coupled transport, Arl1 regulation, actin remodeling, and autophagy — are integrated and switched within one protein remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No structural model of MON2 or its complexes\", \"Regulatory logic governing Golgi-vs-endosome partitioning unknown\", \"Whether functions are sequential or parallel not established\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 5, 6]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [3, 7]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [0, 5, 7]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [4, 6, 7]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [0, 4, 6]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [4, 5, 6]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [7]}\n    ],\n    \"complexes\": [\"MON2:DOPEY2:ATP9A endosomal complex\", \"Dopey1-MON2 cargo adaptor complex\"],\n    \"partners\": [\"DOPEY1\", \"DOPEY2\", \"ATP9A\", \"SNX3\", \"GABARAPL2\", \"Cappuccino\", \"Spire\", \"Rho1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}