{"gene":"AP1G1","run_date":"2026-06-09T22:02:43","timeline":{"discoveries":[{"year":1998,"finding":"Human gamma-adaptin (AP1G1/ADTG) was cloned and shown to encode an 825-amino-acid protein (98.9% identical to mouse) that is a component of the heterotetrameric AP-1 adaptor complex involved in clathrin-coated vesicle formation, mediating transport from the plasma membrane or trans-Golgi network to lysosomes; the gene was mapped to chromosome 16q23 and is ubiquitously expressed.","method":"cDNA cloning, sequencing, Northern blot analysis, fluorescence in situ hybridization, somatic cell hybrid panel","journal":"Genomics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct cloning and expression characterization with chromosomal mapping; single study but multiple orthogonal methods","pmids":["9653655"],"is_preprint":false},{"year":2016,"finding":"A hypomorphic in-frame 6-bp deletion in mouse Ap1g1 (removing two amino acids of the gamma-1 subunit) causes abnormalities specifically in polarized epithelial cells of the inner ear, retina, thyroid, and testis, while a null mutation causes embryonic lethality, establishing that AP1G1-mediated AP-1 sorting of membrane proteins is essential for polarized epithelial cell function in vivo.","method":"Mouse genetic model (spontaneous hypomorphic mutation), histological and phenotypic analysis of homozygous mutants versus null mice","journal":"Mammalian genome","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean in vivo loss-of-function with defined cellular phenotype in multiple tissues; single lab study","pmids":["27090238"],"is_preprint":false},{"year":2017,"finding":"AP1G1 physically associates with both ASCT2 (a glutamine transporter) and EGFR, forming a heterotrimeric molecular complex; knockdown of AP1G1 reduced ASCT2-EGFR association, inhibited cetuximab-mediated internalization of the ASCT2-EGFR complex, and decreased intracellular glutamine uptake and glutathione biosynthesis, establishing AP1G1's role in endosomal sorting of this receptor complex.","method":"Co-immunoprecipitation (physical association), siRNA knockdown with functional readouts (internalization assay, glutamine uptake, glutathione measurement)","journal":"Cancer letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP establishing complex membership plus functional KD phenotype with multiple readouts; single lab","pmids":["28823958"],"is_preprint":false},{"year":2021,"finding":"De novo and bi-allelic missense variants in AP1G1 cause a neurodevelopmental disorder; bi-allelic variants did not disrupt interaction of AP1γ1 with other AP-1 complex subunits but impaired the endosome recycling pathway; dominant de novo variants caused developmental abnormalities in zebrafish when introduced into wild-type embryos; knockout of ap1g1 in zebrafish caused lethal morphological defects rescued by wild-type but not mutant AP1G1 mRNA, confirming loss-of-function pathogenicity.","method":"3D protein modeling, heterologous cell expression assays (protein level assessment), co-immunoprecipitation (subunit interaction), endosome recycling assays, zebrafish ap1g1 knockdown/rescue experiments with wild-type and mutant mRNA microinjection","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (structural modeling, subunit interaction assays, endosome recycling functional assay, zebrafish KO rescue with wild-type vs. mutant mRNA) in a single rigorous study","pmids":["34102099"],"is_preprint":false},{"year":2023,"finding":"CRISPR/Cas9 knockout of ap1g1 in zebrafish causes developmental arrest at the blastula stage; heterozygous ap1g1 fish show reduced fertility and morphological alterations in brain, gonads, and intestinal epithelium associated with dysregulated cadherin-mediated cell adhesion, demonstrating AP1G1's role in regulating polarized epithelial and neuronal tissue organization through vesicular sorting.","method":"CRISPR/Cas9 zebrafish knockout, mRNA expression profiling, immunofluorescence/histological analysis of tissue markers","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean CRISPR KO with defined developmental and tissue phenotypes; single lab, multiple tissue readouts","pmids":["37108275"],"is_preprint":false},{"year":2025,"finding":"AP1G1 was identified as a chaperone/interactor of lactate transporter SLC16A3 via proteomics and thermal proteome profiling; SLC16A3 interaction with AP1G1 determines AP1G1 membrane enrichment, thereby controlling cellular endocytosis activity and host susceptibility to viral entry; disrupting the SLC16A3-AP1G1 interaction (pharmacologically or by SLC16A3 knockdown) reduces AP1G1 membrane localization and decreases viral particle endocytosis.","method":"Metabolomics, proteomics, thermal proteome profiling, Co-IP/interaction assays, SLC16A3 knockdown, membrane fractionation, viral infection assays","journal":"Microbiology spectrum","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal proteomics methods identifying interaction plus functional KD phenotype; single lab, single study","pmids":["40919783"],"is_preprint":false},{"year":2025,"finding":"A novel de novo missense variant (p.Gly66Arg) in AP1G1 alters intracellular distribution of AP-1 complex (shown by immunofluorescence in patient fibroblasts) and fails to rescue ap1g1 knockout zebrafish lethality; co-injection of wild-type and mutant mRNA also failed to rescue, supporting a dominant-negative mechanism for this variant.","method":"Exome sequencing, in silico protein modeling, immunofluorescence in patient fibroblasts, zebrafish KO rescue assay with wild-type and mutant AP1G1 mRNA microinjection","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct functional characterization in patient cells plus zebrafish rescue assay; single lab, two orthogonal models","pmids":["41226632"],"is_preprint":false}],"current_model":"AP1G1 encodes the gamma-1 subunit of the heterotetrameric AP-1 clathrin adaptor complex, which is essential for intracellular vesicular trafficking at the trans-Golgi network and endosomes; it mediates sorting and polarized localization of membrane proteins (including receptor complexes such as ASCT2-EGFR) in epithelial and neuronal cells, regulates endosome recycling, and its membrane localization is controlled by interaction with SLC16A3, with loss-of-function causing embryonic lethality and hypomorphic or missense variants causing tissue-specific defects in polarized epithelia and neurodevelopmental disorders."},"narrative":{"mechanistic_narrative":"AP1G1 encodes the gamma-1 subunit of the heterotetrameric AP-1 clathrin adaptor complex, which directs clathrin-coated vesicle formation and membrane protein sorting between the plasma membrane, trans-Golgi network, and endosomes [PMID:9653655]. Through AP-1, AP1G1 sorts membrane cargo in polarized cells: it physically associates with the ASCT2 glutamine transporter and EGFR in a heterotrimeric complex and is required for receptor-complex internalization, glutamine uptake, and downstream glutathione biosynthesis [PMID:28823958], and it governs endosome recycling [PMID:34102099]. Its membrane enrichment is controlled by interaction with the lactate transporter SLC16A3, which positions AP1G1 to drive endocytosis, including viral particle entry [PMID:40919783]. Disruption of this sorting function impairs the organization of polarized epithelial and neuronal tissues, in part via cadherin-mediated cell adhesion [PMID:37108275]. In vivo, null loss of AP1G1 is embryonic lethal whereas hypomorphic alleles produce tissue-specific defects in polarized epithelia of the inner ear, retina, thyroid, and testis [PMID:27090238]. De novo and bi-allelic missense variants in AP1G1 cause a neurodevelopmental disorder; pathogenic variants impair endosome recycling or AP-1 complex distribution while leaving subunit assembly intact, acting through loss-of-function or dominant-negative mechanisms [PMID:34102099, PMID:41226632].","teleology":[{"year":1998,"claim":"Established the molecular identity of AP1G1 as the gamma-adaptin subunit of the AP-1 adaptor complex, defining its place in clathrin-coated vesicle trafficking before any functional dissection.","evidence":"cDNA cloning, sequencing, Northern blot, FISH, and somatic cell hybrid mapping of human gamma-adaptin","pmids":["9653655"],"confidence":"Medium","gaps":["No direct demonstration of cargo selectivity or sorting specificity","Subcellular dynamics and partner subunits inferred from complex membership, not measured here"]},{"year":2016,"claim":"Linked AP1G1-mediated AP-1 sorting to a concrete physiological requirement, showing it is essential for polarized epithelial function and viability rather than generically housekeeping.","evidence":"Mouse hypomorphic in-frame deletion versus null allele, with histological phenotyping across multiple tissues","pmids":["27090238"],"confidence":"Medium","gaps":["Specific mis-sorted cargoes in affected epithelia not identified","Molecular basis of tissue selectivity unresolved"]},{"year":2017,"claim":"Identified a specific cargo complex (ASCT2-EGFR) sorted by AP1G1, connecting adaptor function to receptor internalization and nutrient/redox metabolism.","evidence":"Reciprocal co-immunoprecipitation plus siRNA knockdown with internalization, glutamine uptake, and glutathione readouts","pmids":["28823958"],"confidence":"Medium","gaps":["Direct binding interface between AP1G1 and cargo not mapped","Single cell-line context; generality across tissues untested"]},{"year":2021,"claim":"Established AP1G1 as a disease gene and pinpointed endosome recycling as the affected step, distinguishing variant pathogenicity from disruption of AP-1 assembly.","evidence":"Human variant identification, subunit interaction co-IP, endosome recycling assays, and zebrafish knockout rescue with wild-type versus mutant mRNA","pmids":["34102099"],"confidence":"High","gaps":["Mechanism by which recycling defect produces neurodevelopmental phenotype unresolved","Genotype-phenotype distinction between dominant and recessive alleles not fully mechanistically explained"]},{"year":2023,"claim":"Tied AP1G1 sorting function to tissue architecture by implicating dysregulated cadherin-mediated adhesion in polarized epithelial and neuronal organization.","evidence":"CRISPR/Cas9 zebrafish knockout and heterozygote analysis with expression profiling and tissue-marker immunofluorescence","pmids":["37108275"],"confidence":"Medium","gaps":["Direct trafficking link between AP1G1 and cadherin not demonstrated","Whether adhesion defect is cause or consequence of polarity loss unclear"]},{"year":2025,"claim":"Revealed that AP1G1 membrane localization is controlled by SLC16A3 binding, defining a regulatory input that sets endocytic capacity and influences viral entry.","evidence":"Proteomics, thermal proteome profiling, co-IP, SLC16A3 knockdown, membrane fractionation, and viral infection assays","pmids":["40919783"],"confidence":"Medium","gaps":["Structural basis of the SLC16A3-AP1G1 interaction unknown","Whether SLC16A3 regulates canonical cargo sorting beyond viral entry untested"]},{"year":2025,"claim":"Characterized a dominant-negative missense variant that mislocalizes the AP-1 complex, refining the spectrum of pathogenic mechanisms in AP1G1 disorder.","evidence":"Exome sequencing, in silico modeling, patient-fibroblast immunofluorescence, and zebrafish knockout rescue with wild-type and mutant mRNA co-injection","pmids":["41226632"],"confidence":"Medium","gaps":["Molecular reason the variant disrupts AP-1 distribution not defined","Single variant; broader allelic series needed to generalize the mechanism"]},{"year":null,"claim":"The full repertoire of AP1G1-sorted cargoes and the structural rules linking specific variants to recycling versus complex-distribution defects remain undefined.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No comprehensive cargo map for AP1G1-dependent sorting","No high-resolution structure of AP1G1 within assembled AP-1 bound to cargo or regulators","Mechanistic basis for tissue-specific vulnerability not resolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,2,3]},{"term_id":"GO:0038024","term_label":"cargo receptor activity","supporting_discovery_ids":[2]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[0]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[2,3]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[5]}],"pathway":[],"complexes":["AP-1 adaptor complex"],"partners":["ASCT2","EGFR","SLC16A3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O43747","full_name":"AP-1 complex subunit gamma-1","aliases":["Adaptor protein complex AP-1 subunit gamma-1","Adaptor-related protein complex 1 subunit gamma-1","Clathrin assembly protein complex 1 gamma-1 large chain","Gamma-adaptin","Gamma1-adaptin","Golgi adaptor HA1/AP1 adaptin subunit gamma-1"],"length_aa":822,"mass_kda":91.4,"function":"Subunit of clathrin-associated adaptor protein complex 1 that plays a role in protein sorting in the late-Golgi/trans-Golgi network (TGN) and/or endosomes. The AP complexes mediate both the recruitment of clathrin to membranes and the recognition of sorting signals within the cytosolic tails of transmembrane cargo molecules. In association with AFTPH/aftiphilin in the aftiphilin/p200/gamma-synergin complex, involved in the trafficking of transferrin from early to recycling endosomes, and the membrane trafficking of furin and the lysosomal enzyme cathepsin D between the trans-Golgi network (TGN) and endosomes (PubMed:15758025)","subcellular_location":"Golgi apparatus; Cytoplasmic vesicle, clathrin-coated vesicle membrane; Cytoplasm; Cytoplasm, perinuclear region; Cytoplasmic vesicle, clathrin-coated vesicle; Membrane, clathrin-coated pit","url":"https://www.uniprot.org/uniprotkb/O43747/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/AP1G1","classification":"Not Classified","n_dependent_lines":92,"n_total_lines":1208,"dependency_fraction":0.076158940397351},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"AKT2","stoichiometry":0.2},{"gene":"CLTA","stoichiometry":0.2},{"gene":"CLTB","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/AP1G1","total_profiled":1310},"omim":[{"mim_id":"619628","title":"AFTIPHILIN; AFTPH","url":"https://www.omim.org/entry/619628"},{"mim_id":"619627","title":"HEAT REPEAT-CONTAINING PROTEIN 5B; HEATR5B","url":"https://www.omim.org/entry/619627"},{"mim_id":"619548","title":"USMANI-RIAZUDDIN SYNDROME, AUTOSOMAL RECESSIVE; USRISR","url":"https://www.omim.org/entry/619548"},{"mim_id":"619467","title":"USMANI-RIAZUDDIN SYNDROME, AUTOSOMAL DOMINANT; USRISD","url":"https://www.omim.org/entry/619467"},{"mim_id":"617366","title":"COILED-COIL DOMAIN-CONTAINING PROTEIN 91; CCDC91","url":"https://www.omim.org/entry/617366"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Enhanced","locations":[{"location":"Golgi apparatus","reliability":"Enhanced"},{"location":"Vesicles","reliability":"Enhanced"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/AP1G1"},"hgnc":{"alias_symbol":[],"prev_symbol":["CLAPG1","ADTG"]},"alphafold":{"accession":"O43747","domains":[{"cath_id":"-","chopping":"435-580","consensus_level":"high","plddt":91.3003,"start":435,"end":580},{"cath_id":"2.60.40.1230","chopping":"706-819","consensus_level":"high","plddt":88.475,"start":706,"end":819}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O43747","model_url":"https://alphafold.ebi.ac.uk/files/AF-O43747-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O43747-F1-predicted_aligned_error_v6.png","plddt_mean":83.75},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=AP1G1","jax_strain_url":"https://www.jax.org/strain/search?query=AP1G1"},"sequence":{"accession":"O43747","fasta_url":"https://rest.uniprot.org/uniprotkb/O43747.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O43747/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O43747"}},"corpus_meta":[{"pmid":"30840267","id":"PMC_30840267","title":"MEG3 promotes liver cancer by activating PI3K/AKT pathway through regulating AP1G1.","date":"2019","source":"European review for medical and pharmacological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/30840267","citation_count":36,"is_preprint":false},{"pmid":"28823958","id":"PMC_28823958","title":"AP1G1 is involved in cetuximab-mediated downregulation of ASCT2-EGFR complex and sensitization of human head and neck squamous cell carcinoma cells to ROS-induced apoptosis.","date":"2017","source":"Cancer letters","url":"https://pubmed.ncbi.nlm.nih.gov/28823958","citation_count":35,"is_preprint":false},{"pmid":"31002129","id":"PMC_31002129","title":"HCP5 promotes colon cancer development by activating AP1G1 via PI3K/AKT pathway.","date":"2019","source":"European review for medical and pharmacological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/31002129","citation_count":25,"is_preprint":false},{"pmid":"34102099","id":"PMC_34102099","title":"De novo and bi-allelic variants in AP1G1 cause neurodevelopmental disorder with developmental delay, intellectual disability, and epilepsy.","date":"2021","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/34102099","citation_count":23,"is_preprint":false},{"pmid":"27090238","id":"PMC_27090238","title":"A hypomorphic mutation of the gamma-1 adaptin gene (Ap1g1) causes inner ear, retina, thyroid, and testes abnormalities in mice.","date":"2016","source":"Mammalian genome : official journal of the International Mammalian Genome Society","url":"https://pubmed.ncbi.nlm.nih.gov/27090238","citation_count":17,"is_preprint":false},{"pmid":"9653655","id":"PMC_9653655","title":"Cloning, expression pattern, and chromosomal assignment to 16q23 of the human gamma-adaptin gene (ADTG).","date":"1998","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/9653655","citation_count":7,"is_preprint":false},{"pmid":"37108275","id":"PMC_37108275","title":"Deficiency of AP1 Complex Ap1g1 in Zebrafish Model Led to Perturbation of Neurodevelopment, Female and Male Fertility; New Insight to Understand Adaptinopathies.","date":"2023","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/37108275","citation_count":5,"is_preprint":false},{"pmid":"36212964","id":"PMC_36212964","title":"MicroRNA-641 Inhibits Endometrial Cancer Progression via Targeting AP1G1.","date":"2022","source":"Evidence-based complementary and alternative medicine : eCAM","url":"https://pubmed.ncbi.nlm.nih.gov/36212964","citation_count":4,"is_preprint":false},{"pmid":"41226632","id":"PMC_41226632","title":"Usmani-Riazuddin Syndrome: Functional Characterization of a Novel c.196G>A Variant in the AP1G1 Gene and Phenotypic Insights Using Zebrafish as a Vertebrate Model.","date":"2025","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/41226632","citation_count":0,"is_preprint":false},{"pmid":"40919783","id":"PMC_40919783","title":"Attenuate host susceptibility to respiratory virus invasion by inhibiting interactions between host proteins SLC16A3 and AP1G1.","date":"2025","source":"Microbiology spectrum","url":"https://pubmed.ncbi.nlm.nih.gov/40919783","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7956,"output_tokens":2017,"usd":0.027061,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9045,"output_tokens":2721,"usd":0.056625,"stage2_stop_reason":"end_turn"},"total_usd":0.083686,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1998,\n      \"finding\": \"Human gamma-adaptin (AP1G1/ADTG) was cloned and shown to encode an 825-amino-acid protein (98.9% identical to mouse) that is a component of the heterotetrameric AP-1 adaptor complex involved in clathrin-coated vesicle formation, mediating transport from the plasma membrane or trans-Golgi network to lysosomes; the gene was mapped to chromosome 16q23 and is ubiquitously expressed.\",\n      \"method\": \"cDNA cloning, sequencing, Northern blot analysis, fluorescence in situ hybridization, somatic cell hybrid panel\",\n      \"journal\": \"Genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct cloning and expression characterization with chromosomal mapping; single study but multiple orthogonal methods\",\n      \"pmids\": [\"9653655\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"A hypomorphic in-frame 6-bp deletion in mouse Ap1g1 (removing two amino acids of the gamma-1 subunit) causes abnormalities specifically in polarized epithelial cells of the inner ear, retina, thyroid, and testis, while a null mutation causes embryonic lethality, establishing that AP1G1-mediated AP-1 sorting of membrane proteins is essential for polarized epithelial cell function in vivo.\",\n      \"method\": \"Mouse genetic model (spontaneous hypomorphic mutation), histological and phenotypic analysis of homozygous mutants versus null mice\",\n      \"journal\": \"Mammalian genome\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean in vivo loss-of-function with defined cellular phenotype in multiple tissues; single lab study\",\n      \"pmids\": [\"27090238\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"AP1G1 physically associates with both ASCT2 (a glutamine transporter) and EGFR, forming a heterotrimeric molecular complex; knockdown of AP1G1 reduced ASCT2-EGFR association, inhibited cetuximab-mediated internalization of the ASCT2-EGFR complex, and decreased intracellular glutamine uptake and glutathione biosynthesis, establishing AP1G1's role in endosomal sorting of this receptor complex.\",\n      \"method\": \"Co-immunoprecipitation (physical association), siRNA knockdown with functional readouts (internalization assay, glutamine uptake, glutathione measurement)\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP establishing complex membership plus functional KD phenotype with multiple readouts; single lab\",\n      \"pmids\": [\"28823958\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"De novo and bi-allelic missense variants in AP1G1 cause a neurodevelopmental disorder; bi-allelic variants did not disrupt interaction of AP1γ1 with other AP-1 complex subunits but impaired the endosome recycling pathway; dominant de novo variants caused developmental abnormalities in zebrafish when introduced into wild-type embryos; knockout of ap1g1 in zebrafish caused lethal morphological defects rescued by wild-type but not mutant AP1G1 mRNA, confirming loss-of-function pathogenicity.\",\n      \"method\": \"3D protein modeling, heterologous cell expression assays (protein level assessment), co-immunoprecipitation (subunit interaction), endosome recycling assays, zebrafish ap1g1 knockdown/rescue experiments with wild-type and mutant mRNA microinjection\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (structural modeling, subunit interaction assays, endosome recycling functional assay, zebrafish KO rescue with wild-type vs. mutant mRNA) in a single rigorous study\",\n      \"pmids\": [\"34102099\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"CRISPR/Cas9 knockout of ap1g1 in zebrafish causes developmental arrest at the blastula stage; heterozygous ap1g1 fish show reduced fertility and morphological alterations in brain, gonads, and intestinal epithelium associated with dysregulated cadherin-mediated cell adhesion, demonstrating AP1G1's role in regulating polarized epithelial and neuronal tissue organization through vesicular sorting.\",\n      \"method\": \"CRISPR/Cas9 zebrafish knockout, mRNA expression profiling, immunofluorescence/histological analysis of tissue markers\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean CRISPR KO with defined developmental and tissue phenotypes; single lab, multiple tissue readouts\",\n      \"pmids\": [\"37108275\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"AP1G1 was identified as a chaperone/interactor of lactate transporter SLC16A3 via proteomics and thermal proteome profiling; SLC16A3 interaction with AP1G1 determines AP1G1 membrane enrichment, thereby controlling cellular endocytosis activity and host susceptibility to viral entry; disrupting the SLC16A3-AP1G1 interaction (pharmacologically or by SLC16A3 knockdown) reduces AP1G1 membrane localization and decreases viral particle endocytosis.\",\n      \"method\": \"Metabolomics, proteomics, thermal proteome profiling, Co-IP/interaction assays, SLC16A3 knockdown, membrane fractionation, viral infection assays\",\n      \"journal\": \"Microbiology spectrum\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal proteomics methods identifying interaction plus functional KD phenotype; single lab, single study\",\n      \"pmids\": [\"40919783\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"A novel de novo missense variant (p.Gly66Arg) in AP1G1 alters intracellular distribution of AP-1 complex (shown by immunofluorescence in patient fibroblasts) and fails to rescue ap1g1 knockout zebrafish lethality; co-injection of wild-type and mutant mRNA also failed to rescue, supporting a dominant-negative mechanism for this variant.\",\n      \"method\": \"Exome sequencing, in silico protein modeling, immunofluorescence in patient fibroblasts, zebrafish KO rescue assay with wild-type and mutant AP1G1 mRNA microinjection\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct functional characterization in patient cells plus zebrafish rescue assay; single lab, two orthogonal models\",\n      \"pmids\": [\"41226632\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"AP1G1 encodes the gamma-1 subunit of the heterotetrameric AP-1 clathrin adaptor complex, which is essential for intracellular vesicular trafficking at the trans-Golgi network and endosomes; it mediates sorting and polarized localization of membrane proteins (including receptor complexes such as ASCT2-EGFR) in epithelial and neuronal cells, regulates endosome recycling, and its membrane localization is controlled by interaction with SLC16A3, with loss-of-function causing embryonic lethality and hypomorphic or missense variants causing tissue-specific defects in polarized epithelia and neurodevelopmental disorders.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"AP1G1 encodes the gamma-1 subunit of the heterotetrameric AP-1 clathrin adaptor complex, which directs clathrin-coated vesicle formation and membrane protein sorting between the plasma membrane, trans-Golgi network, and endosomes [#0]. Through AP-1, AP1G1 sorts membrane cargo in polarized cells: it physically associates with the ASCT2 glutamine transporter and EGFR in a heterotrimeric complex and is required for receptor-complex internalization, glutamine uptake, and downstream glutathione biosynthesis [#2], and it governs endosome recycling [#3]. Its membrane enrichment is controlled by interaction with the lactate transporter SLC16A3, which positions AP1G1 to drive endocytosis, including viral particle entry [#5]. Disruption of this sorting function impairs the organization of polarized epithelial and neuronal tissues, in part via cadherin-mediated cell adhesion [#4]. In vivo, null loss of AP1G1 is embryonic lethal whereas hypomorphic alleles produce tissue-specific defects in polarized epithelia of the inner ear, retina, thyroid, and testis [#1]. De novo and bi-allelic missense variants in AP1G1 cause a neurodevelopmental disorder; pathogenic variants impair endosome recycling or AP-1 complex distribution while leaving subunit assembly intact, acting through loss-of-function or dominant-negative mechanisms [#3, #6].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Established the molecular identity of AP1G1 as the gamma-adaptin subunit of the AP-1 adaptor complex, defining its place in clathrin-coated vesicle trafficking before any functional dissection.\",\n      \"evidence\": \"cDNA cloning, sequencing, Northern blot, FISH, and somatic cell hybrid mapping of human gamma-adaptin\",\n      \"pmids\": [\"9653655\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No direct demonstration of cargo selectivity or sorting specificity\",\n        \"Subcellular dynamics and partner subunits inferred from complex membership, not measured here\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Linked AP1G1-mediated AP-1 sorting to a concrete physiological requirement, showing it is essential for polarized epithelial function and viability rather than generically housekeeping.\",\n      \"evidence\": \"Mouse hypomorphic in-frame deletion versus null allele, with histological phenotyping across multiple tissues\",\n      \"pmids\": [\"27090238\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Specific mis-sorted cargoes in affected epithelia not identified\",\n        \"Molecular basis of tissue selectivity unresolved\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identified a specific cargo complex (ASCT2-EGFR) sorted by AP1G1, connecting adaptor function to receptor internalization and nutrient/redox metabolism.\",\n      \"evidence\": \"Reciprocal co-immunoprecipitation plus siRNA knockdown with internalization, glutamine uptake, and glutathione readouts\",\n      \"pmids\": [\"28823958\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct binding interface between AP1G1 and cargo not mapped\",\n        \"Single cell-line context; generality across tissues untested\"\n      ]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Established AP1G1 as a disease gene and pinpointed endosome recycling as the affected step, distinguishing variant pathogenicity from disruption of AP-1 assembly.\",\n      \"evidence\": \"Human variant identification, subunit interaction co-IP, endosome recycling assays, and zebrafish knockout rescue with wild-type versus mutant mRNA\",\n      \"pmids\": [\"34102099\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mechanism by which recycling defect produces neurodevelopmental phenotype unresolved\",\n        \"Genotype-phenotype distinction between dominant and recessive alleles not fully mechanistically explained\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Tied AP1G1 sorting function to tissue architecture by implicating dysregulated cadherin-mediated adhesion in polarized epithelial and neuronal organization.\",\n      \"evidence\": \"CRISPR/Cas9 zebrafish knockout and heterozygote analysis with expression profiling and tissue-marker immunofluorescence\",\n      \"pmids\": [\"37108275\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Direct trafficking link between AP1G1 and cadherin not demonstrated\",\n        \"Whether adhesion defect is cause or consequence of polarity loss unclear\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Revealed that AP1G1 membrane localization is controlled by SLC16A3 binding, defining a regulatory input that sets endocytic capacity and influences viral entry.\",\n      \"evidence\": \"Proteomics, thermal proteome profiling, co-IP, SLC16A3 knockdown, membrane fractionation, and viral infection assays\",\n      \"pmids\": [\"40919783\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Structural basis of the SLC16A3-AP1G1 interaction unknown\",\n        \"Whether SLC16A3 regulates canonical cargo sorting beyond viral entry untested\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Characterized a dominant-negative missense variant that mislocalizes the AP-1 complex, refining the spectrum of pathogenic mechanisms in AP1G1 disorder.\",\n      \"evidence\": \"Exome sequencing, in silico modeling, patient-fibroblast immunofluorescence, and zebrafish knockout rescue with wild-type and mutant mRNA co-injection\",\n      \"pmids\": [\"41226632\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Molecular reason the variant disrupts AP-1 distribution not defined\",\n        \"Single variant; broader allelic series needed to generalize the mechanism\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The full repertoire of AP1G1-sorted cargoes and the structural rules linking specific variants to recycling versus complex-distribution defects remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No comprehensive cargo map for AP1G1-dependent sorting\",\n        \"No high-resolution structure of AP1G1 within assembled AP-1 bound to cargo or regulators\",\n        \"Mechanistic basis for tissue-specific vulnerability not resolved\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 2, 3]},\n      {\"term_id\": \"GO:0038024\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [2, 3]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": []}\n    ],\n    \"complexes\": [\"AP-1 adaptor complex\"],\n    \"partners\": [\"ASCT2\", \"EGFR\", \"SLC16A3\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}