{"gene":"NAPG","run_date":"2026-06-10T05:19:52","timeline":{"discoveries":[{"year":2015,"finding":"γ-SNAP (encoded by NAPG) interacts with a limited range of SNAREs, including endosomal SNAREs (e.g., syntaxin-7-containing complexes), and mediates disassembly of these SNARE complexes in a manner analogous to α-SNAP, functioning specifically at endosomes rather than broadly across all trafficking compartments.","method":"Immunoprecipitation, mass spectrometry, siRNA-mediated knockdown, overexpression, live-cell imaging of endosome morphology and distribution, functional trafficking assays (EGFR and transferrin trafficking)","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP with MS identification of interactors, siRNA knockdown with specific trafficking phenotypes, and overexpression rescue in a single lab with multiple orthogonal methods","pmids":["26101353"],"is_preprint":false},{"year":2015,"finding":"Depletion of γ-SNAP (NAPG) by siRNA partially suppresses exit of EGFR and transferrin from EEA1-positive early endosomes, delaying their degradation and uptake, establishing a defined role for NAPG in endosomal trafficking.","method":"siRNA knockdown, fluorescence microscopy tracking of EGFR and transferrin trafficking, EEA1 marker co-localization","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — single lab, clean knockdown with specific endosomal trafficking phenotype, but single method for trafficking readout","pmids":["26101353"],"is_preprint":false},{"year":2010,"finding":"NAPG (γ-SNAP) was identified as a binding partner of the cytoplasmic domain of LRP1 in a split-ubiquitin yeast two-hybrid screen.","method":"Split-ubiquitin yeast two-hybrid screen","journal":"Molecular neurodegeneration","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single method (yeast two-hybrid), not further validated for NAPG specifically in the paper; NYGGF4 was the focus of validation","pmids":["20205790"],"is_preprint":false},{"year":2025,"finding":"NAPG inhibits osteogenic differentiation, as verified at the protein and cellular levels by ALP assay, Alizarin Red staining (ARS), and Western blot experiments.","method":"ALP assay, Alizarin Red staining, Western blot, cellular osteogenic differentiation assay","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — single lab, multiple orthogonal cellular assays (ALP, ARS, Western blot) demonstrating a specific functional consequence of NAPG on osteogenic differentiation","pmids":["40603950"],"is_preprint":false}],"current_model":"γ-SNAP (NAPG) is an NSF attachment protein that selectively interacts with endosomal SNARE complexes (including syntaxin-7-containing complexes) and, together with NSF, drives their disassembly to regulate endosomal membrane trafficking — specifically controlling the exit of EGF receptor and transferrin from early endosomes — with emerging evidence also suggesting a role in inhibiting osteogenic differentiation."},"narrative":{"mechanistic_narrative":"γ-SNAP (NAPG) is an NSF attachment protein that operates selectively in endosomal membrane trafficking by engaging a restricted set of SNAREs, including syntaxin-7-containing endosomal complexes, and mediating their disassembly in a manner analogous to α-SNAP [PMID:26101353]. Functionally, depletion of NAPG partially blocks the exit of EGF receptor and transferrin from EEA1-positive early endosomes, delaying receptor degradation and cargo uptake and establishing a defined role in early endosome cargo progression [PMID:26101353]. A separate cellular study links NAPG to inhibition of osteogenic differentiation [PMID:40603950]. Beyond these findings, the molecular details of NAPG's recruitment, structure, and broader pathway context have not been characterized in the available corpus.","teleology":[{"year":2010,"claim":"An initial interaction screen placed NAPG in a candidate protein-protein network by identifying it as a binding partner of the LRP1 cytoplasmic domain, though without functional follow-up for NAPG.","evidence":"Split-ubiquitin yeast two-hybrid screen","pmids":["20205790"],"confidence":"Low","gaps":["Single method (yeast two-hybrid) not independently validated for NAPG","No demonstration of a functional consequence of the LRP1 interaction","NAPG was not the focus of validation in the study"]},{"year":2015,"claim":"The question of what compartment NAPG acts in and which SNAREs it engages was answered by showing it interacts with a limited range of endosomal SNAREs (including syntaxin-7 complexes) and mediates their disassembly like α-SNAP, defining it as an endosome-selective SNAP rather than a general trafficking factor.","evidence":"Reciprocal co-IP with mass spectrometry, siRNA knockdown, overexpression, and live-cell endosome imaging","pmids":["26101353"],"confidence":"High","gaps":["Structural basis of selective SNARE engagement not defined","Mechanism distinguishing γ-SNAP from α-SNAP specificity unresolved","Dependence on NSF demonstrated only in this single study"]},{"year":2015,"claim":"The physiological output of NAPG-mediated disassembly was established by showing its depletion suppresses EGFR and transferrin exit from EEA1-positive early endosomes, linking SNARE disassembly to cargo progression and receptor degradation kinetics.","evidence":"siRNA knockdown with fluorescence microscopy tracking of EGFR/transferrin and EEA1 co-localization","pmids":["26101353"],"confidence":"Medium","gaps":["Single-method trafficking readout","Partial (not complete) suppression leaves the full requirement for NAPG unclear","Downstream effects on signaling not assessed"]},{"year":2025,"claim":"A new cellular role was identified by showing NAPG inhibits osteogenic differentiation, extending its functional relevance beyond endosomal trafficking.","evidence":"ALP assay, Alizarin Red staining, and Western blot in osteogenic differentiation assays","pmids":["40603950"],"confidence":"Medium","gaps":["Mechanistic link between endosomal SNARE function and osteogenesis not established","Single-lab finding with cellular but not in vivo validation","Molecular pathway mediating the differentiation effect unknown"]},{"year":null,"claim":"How NAPG achieves its endosome selectivity, how it cooperates with NSF mechanistically, and how its trafficking role connects to its effect on osteogenic differentiation remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of NAPG-SNARE-NSF engagement","Mechanism of compartment-restricted SNARE recognition undefined","Causal connection between trafficking function and osteogenesis unestablished"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[0,1]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[0,1]}],"complexes":[],"partners":["STX7","NSF","LRP1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q99747","full_name":"Gamma-soluble NSF attachment protein","aliases":["N-ethylmaleimide-sensitive factor attachment protein gamma"],"length_aa":312,"mass_kda":34.7,"function":"Required for vesicular transport between the endoplasmic reticulum and the Golgi apparatus","subcellular_location":"Membrane; Golgi 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\"Immunoprecipitation, mass spectrometry, siRNA-mediated knockdown, overexpression, live-cell imaging of endosome morphology and distribution, functional trafficking assays (EGFR and transferrin trafficking)\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP with MS identification of interactors, siRNA knockdown with specific trafficking phenotypes, and overexpression rescue in a single lab with multiple orthogonal methods\",\n      \"pmids\": [\"26101353\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Depletion of γ-SNAP (NAPG) by siRNA partially suppresses exit of EGFR and transferrin from EEA1-positive early endosomes, delaying their degradation and uptake, establishing a defined role for NAPG in endosomal trafficking.\",\n      \"method\": \"siRNA knockdown, fluorescence microscopy tracking of EGFR and transferrin trafficking, EEA1 marker co-localization\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — single lab, clean knockdown with specific endosomal trafficking phenotype, but single method for trafficking readout\",\n      \"pmids\": [\"26101353\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"NAPG (γ-SNAP) was identified as a binding partner of the cytoplasmic domain of LRP1 in a split-ubiquitin yeast two-hybrid screen.\",\n      \"method\": \"Split-ubiquitin yeast two-hybrid screen\",\n      \"journal\": \"Molecular neurodegeneration\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single method (yeast two-hybrid), not further validated for NAPG specifically in the paper; NYGGF4 was the focus of validation\",\n      \"pmids\": [\"20205790\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"NAPG inhibits osteogenic differentiation, as verified at the protein and cellular levels by ALP assay, Alizarin Red staining (ARS), and Western blot experiments.\",\n      \"method\": \"ALP assay, Alizarin Red staining, Western blot, cellular osteogenic differentiation assay\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — single lab, multiple orthogonal cellular assays (ALP, ARS, Western blot) demonstrating a specific functional consequence of NAPG on osteogenic differentiation\",\n      \"pmids\": [\"40603950\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"γ-SNAP (NAPG) is an NSF attachment protein that selectively interacts with endosomal SNARE complexes (including syntaxin-7-containing complexes) and, together with NSF, drives their disassembly to regulate endosomal membrane trafficking — specifically controlling the exit of EGF receptor and transferrin from early endosomes — with emerging evidence also suggesting a role in inhibiting osteogenic differentiation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"γ-SNAP (NAPG) is an NSF attachment protein that operates selectively in endosomal membrane trafficking by engaging a restricted set of SNAREs, including syntaxin-7-containing endosomal complexes, and mediating their disassembly in a manner analogous to α-SNAP [#0]. Functionally, depletion of NAPG partially blocks the exit of EGF receptor and transferrin from EEA1-positive early endosomes, delaying receptor degradation and cargo uptake and establishing a defined role in early endosome cargo progression [#1]. A separate cellular study links NAPG to inhibition of osteogenic differentiation [#3]. Beyond these findings, the molecular details of NAPG's recruitment, structure, and broader pathway context have not been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 2010,\n      \"claim\": \"An initial interaction screen placed NAPG in a candidate protein-protein network by identifying it as a binding partner of the LRP1 cytoplasmic domain, though without functional follow-up for NAPG.\",\n      \"evidence\": \"Split-ubiquitin yeast two-hybrid screen\",\n      \"pmids\": [\"20205790\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Single method (yeast two-hybrid) not independently validated for NAPG\",\n        \"No demonstration of a functional consequence of the LRP1 interaction\",\n        \"NAPG was not the focus of validation in the study\"\n      ]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"The question of what compartment NAPG acts in and which SNAREs it engages was answered by showing it interacts with a limited range of endosomal SNAREs (including syntaxin-7 complexes) and mediates their disassembly like α-SNAP, defining it as an endosome-selective SNAP rather than a general trafficking factor.\",\n      \"evidence\": \"Reciprocal co-IP with mass spectrometry, siRNA knockdown, overexpression, and live-cell endosome imaging\",\n      \"pmids\": [\"26101353\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis of selective SNARE engagement not defined\",\n        \"Mechanism distinguishing γ-SNAP from α-SNAP specificity unresolved\",\n        \"Dependence on NSF demonstrated only in this single study\"\n      ]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"The physiological output of NAPG-mediated disassembly was established by showing its depletion suppresses EGFR and transferrin exit from EEA1-positive early endosomes, linking SNARE disassembly to cargo progression and receptor degradation kinetics.\",\n      \"evidence\": \"siRNA knockdown with fluorescence microscopy tracking of EGFR/transferrin and EEA1 co-localization\",\n      \"pmids\": [\"26101353\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single-method trafficking readout\",\n        \"Partial (not complete) suppression leaves the full requirement for NAPG unclear\",\n        \"Downstream effects on signaling not assessed\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"A new cellular role was identified by showing NAPG inhibits osteogenic differentiation, extending its functional relevance beyond endosomal trafficking.\",\n      \"evidence\": \"ALP assay, Alizarin Red staining, and Western blot in osteogenic differentiation assays\",\n      \"pmids\": [\"40603950\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanistic link between endosomal SNARE function and osteogenesis not established\",\n        \"Single-lab finding with cellular but not in vivo validation\",\n        \"Molecular pathway mediating the differentiation effect unknown\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How NAPG achieves its endosome selectivity, how it cooperates with NSF mechanistically, and how its trafficking role connects to its effect on osteogenic differentiation remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No structural model of NAPG-SNARE-NSF engagement\",\n        \"Mechanism of compartment-restricted SNARE recognition undefined\",\n        \"Causal connection between trafficking function and osteogenesis unestablished\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"STX7\", \"NSF\", \"LRP1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":2,"faith_total":3,"faith_pct":66.66666666666667}}