{"gene":"CNIH1","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":2007,"finding":"Human CNIH1 (CNIH) localizes primarily to the endoplasmic reticulum, associates with immature TGFα family proteins, and functions as a cargo receptor required for their transport, processing, and secretion; increased CNIH expression retains TGFα proteins in the ER, while loss of CNIH impairs their transport and secretion. Human CNIH complements loss of yeast Erv14 in axial budding.","method":"Subcellular fractionation, co-immunoprecipitation, complementation assay in yeast (Erv14 deletion), overexpression and knockdown in mammalian cells with secretion/processing readouts","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal functional assays (yeast complementation + mammalian gain/loss-of-function), multiple orthogonal methods, replicated across species","pmids":["17607000"],"is_preprint":false},{"year":2016,"finding":"CNIH1 acts as a cargo receptor for proTGFα in COPII-mediated ER export. In a CNIH1-knockout HeLa cell line generated by CRISPR/Cas9, proTGFα packaging into COPII vesicles is severely impaired. Cell-free assays show that both CNIH1 and auxiliary cytosolic factor(s) are required for efficient recruitment of proTGFα to the COPII coat, and that cargo recruitment precedes and may be mechanistically distinct from subsequent packaging into COPII vesicles.","method":"CRISPR/Cas9 knockout, cell-free COPII vesicle budding assay, in vitro reconstitution of cargo recruitment to COPII coat","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 1 / Moderate — cell-free reconstitution assay plus clean genetic knockout with functional readout, single lab but two orthogonal methods","pmids":["27122606"],"is_preprint":false},{"year":2025,"finding":"CNIH1 is identified by a genome-wide CRISPR/Cas9 screen as a dedicated ER-to-PM export factor for the δ-opioid receptor (DOR) and a subset of class A GPCRs. In CNIH1-deficient cells, DOR is retained intracellularly with immature glycosylation and shows reduced plasma-membrane signaling. CNIH1 localizes to ER exit sites and the Golgi, directly interacts with opioid receptors, and requires its putative COPII-binding site for GPCR export. CNIH1 is functionally distinct from other human cornichon homologs in this selective GPCR-sorting role.","method":"Genome-wide CRISPR/Cas9 screen, synchronized cargo-release assay, co-immunoprecipitation (direct interaction), glycosylation analysis, CNIH1 knockout/knockdown with PM signaling readout, subcellular localization by imaging, COPII-binding site mutagenesis","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (screen + co-IP + mutagenesis + localization), single lab, preprint not yet peer-reviewed","pmids":["bio_10.1101_2025.10.27.684930"],"is_preprint":true},{"year":2014,"finding":"CNIH1 physically binds to AMPA receptors via conserved membrane-proximal residues shared with CNIH-2/3, but modulates AMPAR gating at significantly lower magnitude than CNIH-3 because it lacks extracellular loop residues present in CNIH-2/3 that are critical for both AMPAR interaction and gating modulation. Thus CNIH1 binding to AMPARs can be dissociated from functional gating modulation.","method":"Peptide array-based screening, in vitro mutagenesis, single-particle electron microscopy of AMPAR-CNIH complexes, electrophysiology in heterologous cells","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro mutagenesis combined with structural (EM) and functional (electrophysiology) readouts, single lab but multiple orthogonal methods","pmids":["25186755"],"is_preprint":false},{"year":2012,"finding":"CNIH-1 does not slow deactivation or desensitization of GluA2-containing or calcium-permeable AMPARs expressed in tsA201 cells, in contrast to CNIH-2 and CNIH-3, establishing that CNIH1 lacks the functional gating-modulatory activity of its paralogs on AMPARs.","method":"Heterologous expression in tsA201 cells, whole-cell patch-clamp electrophysiology","journal":"The Journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean electrophysiological assay in recombinant system; negative result for CNIH1 gating modulation, single lab","pmids":["22815494"],"is_preprint":false},{"year":1999,"finding":"Mouse Cnih (ortholog of CNIH1) mRNA is a maternal transcript highly abundant in full-grown oocytes and ovulated unfertilized eggs, with specific localization to ovarian oocytes by in situ hybridization. The transcript lacks cytoplasmic polyadenylation elements, suggesting translation occurs in the full-grown oocyte before ovulation but not after. The gene maps to mouse chromosome 10.","method":"EST identification, Northern blot, RT-PCR, in situ hybridization, genetic mapping","journal":"Development genes and evolution","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct localization by in situ hybridization with RNA-level functional inference (polyadenylation analysis), multiple complementary methods, single lab","pmids":["10022955"],"is_preprint":false},{"year":2026,"finding":"Human CNIH1, CNIH2, and CNIH4 expressed in S. cerevisiae (replacing endogenous Erv14) support plasma-membrane targeting and functioning of the human Na+/H+ antiporter NHA2, identifying NHA2 as a novel cargo of cornichon COPII cargo receptors. CNIH1 (along with other human CNIHs) functionally complements yeast Erv14 phenotypes related to monovalent-cation homeostasis.","method":"Yeast complementation assay (ERV14 replacement), functional ion transport assays, plasma-membrane targeting analysis","journal":"Protein science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic complementation with functional readout in yeast, single lab, single publication","pmids":["41676957"],"is_preprint":false}],"current_model":"CNIH1 (also known as TGAM77/CNIH) is a conserved ER-resident transmembrane protein that functions as a COPII cargo receptor: it associates with TGFα family precursors in the ER, promotes their ER exit and secretion, physically interacts with opioid and other class A GPCRs to drive their anterograde ER-to-plasma-membrane transport via a COPII-binding mechanism, and can also traffic the Na+/H+ antiporter NHA2; although CNIH1 physically binds AMPA receptor subunits via conserved membrane-proximal residues, it lacks the extracellular loop elements of CNIH-2/3 required for robust AMPAR gating modulation."},"narrative":{"mechanistic_narrative":"CNIH1 is a conserved endoplasmic reticulum-resident cornichon-family protein that functions as a COPII cargo receptor, selecting specific membrane-associated cargoes for ER export and onward secretion or surface delivery [PMID:17607000, PMID:27122606]. It localizes primarily to the ER and ER exit sites, associates with immature TGFα family precursors, and is required for their transport, processing, and secretion; its expression level tunes cargo retention versus export, and it functionally substitutes for yeast Erv14 [PMID:17607000]. Mechanistically, CNIH1 recruits proTGFα to the COPII coat in concert with auxiliary cytosolic factors, a recruitment step that precedes and is distinguishable from packaging into COPII vesicles [PMID:27122606]. Beyond TGFα, CNIH1 acts as a selective ER-to-plasma-membrane export factor for the δ-opioid receptor and a subset of class A GPCRs, directly binding these receptors and requiring its COPII-binding site for their anterograde trafficking [PMID:bio_10.1101_2025.10.27.684930], and it can also support surface targeting of the Na+/H+ antiporter NHA2 [PMID:41676957]. Although CNIH1 physically binds AMPA receptor subunits through conserved membrane-proximal residues, it lacks the extracellular loop elements present in CNIH-2/3 and therefore does not confer the AMPAR gating modulation characteristic of its paralogs, dissociating receptor binding from functional gating control [PMID:25186755, PMID:22815494].","teleology":[{"year":1999,"claim":"Established the earliest expression context for the mammalian cornichon ortholog, showing it is a maternally deposited oocyte transcript before any molecular function was known.","evidence":"EST identification, Northern blot, in situ hybridization and genetic mapping of mouse Cnih","pmids":["10022955"],"confidence":"Medium","gaps":["No protein-level function assigned","Cargo receptor role not yet identified","Relevance of oocyte expression to trafficking function unaddressed"]},{"year":2007,"claim":"Defined CNIH1 as an ER cargo receptor by showing it associates with immature TGFα precursors and controls their transport and secretion, with cross-species rescue of yeast Erv14.","evidence":"Subcellular fractionation, co-IP, yeast Erv14 complementation, and gain/loss-of-function in mammalian cells with secretion readouts","pmids":["17607000"],"confidence":"High","gaps":["Does not define the COPII-coat interaction biochemically","Cargo specificity beyond TGFα family unknown","Step at which CNIH1 acts in COPII budding not resolved"]},{"year":2016,"claim":"Resolved where CNIH1 acts in the export pathway, showing it is required to recruit proTGFα to the COPII coat as a step distinct from vesicle packaging, with auxiliary cytosolic factors.","evidence":"CRISPR/Cas9 knockout in HeLa, cell-free COPII budding assay, and in vitro reconstitution of cargo recruitment","pmids":["27122606"],"confidence":"High","gaps":["Identity of auxiliary cytosolic factor(s) not determined","Direct CNIH1-COPII contact residues not mapped here","Mechanistic separation of recruitment vs packaging not structurally defined"]},{"year":2014,"claim":"Determined that CNIH1 binds AMPA receptors but cannot modulate their gating, localizing the gating-modulatory determinants to paralog-specific extracellular loop residues absent in CNIH1.","evidence":"Peptide array screening, mutagenesis, single-particle EM of AMPAR-CNIH complexes, and electrophysiology in heterologous cells","pmids":["25186755"],"confidence":"High","gaps":["Physiological significance of CNIH1-AMPAR binding without gating effect unclear","Whether CNIH1 traffics AMPARs in neurons not tested","No endogenous neuronal validation"]},{"year":2012,"claim":"Provided the functional negative control distinguishing CNIH1 from its paralogs, confirming it does not slow AMPAR deactivation or desensitization.","evidence":"Heterologous expression in tsA201 cells with whole-cell patch-clamp electrophysiology","pmids":["22815494"],"confidence":"Medium","gaps":["Negative result in recombinant system only","Does not address CNIH1 binding to AMPARs","Single lab"]},{"year":2025,"claim":"Broadened CNIH1's cargo repertoire to GPCRs, identifying it as a selective ER-to-PM export factor for the δ-opioid receptor and a subset of class A GPCRs that requires its COPII-binding site.","evidence":"Genome-wide CRISPR screen, synchronized cargo-release assay, co-IP, glycosylation analysis, localization imaging and COPII-binding-site mutagenesis (preprint)","pmids":["bio_10.1101_2025.10.27.684930"],"confidence":"Medium","gaps":["Preprint, not yet peer-reviewed","Determinants of GPCR cargo selectivity not defined","In vivo physiological role in opioid signaling untested"]},{"year":2026,"claim":"Extended CNIH1 cargo range to an ion transporter, showing it supports plasma-membrane targeting and function of the Na+/H+ antiporter NHA2.","evidence":"Yeast Erv14-replacement complementation with functional ion transport and PM-targeting assays","pmids":["41676957"],"confidence":"Medium","gaps":["Demonstrated in yeast surrogate rather than native mammalian cells","Direct CNIH1-NHA2 interaction not shown","Specificity versus other human cornichons not dissected"]},{"year":null,"claim":"How CNIH1 achieves cargo selectivity across structurally diverse clients (TGFα precursors, class A GPCRs, ion transporters) and what cytosolic cofactors and COPII contacts govern recruitment remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying cargo recognition determinant identified","Auxiliary cytosolic factor(s) uncharacterized","No high-resolution structure of CNIH1-cargo or CNIH1-COPII complex"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0038024","term_label":"cargo receptor activity","supporting_discovery_ids":[0,1,2]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[0,2]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[2]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[0,1,2]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[1,2]}],"complexes":["COPII coat"],"partners":["TGFA","OPRD1","NHA2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O95406","full_name":"Protein cornichon homolog 1","aliases":["Cornichon family AMPA receptor auxiliary protein 1","Protein cornichon homolog","T-cell growth-associated molecule 77","TGAM77"],"length_aa":144,"mass_kda":16.7,"function":"Involved in the selective transport and maturation of TGF-alpha family proteins","subcellular_location":"Endoplasmic reticulum membrane; Golgi apparatus membrane","url":"https://www.uniprot.org/uniprotkb/O95406/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CNIH1","classification":"Not Classified","n_dependent_lines":33,"n_total_lines":1208,"dependency_fraction":0.027317880794701987},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/CNIH1","total_profiled":1310},"omim":[{"mim_id":"611287","title":"CORNICHON FAMILY AMPA RECEPTOR AUXILIARY PROTEIN 1; CNIH1","url":"https://www.omim.org/entry/611287"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Vesicles","reliability":"Uncertain"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/CNIH1"},"hgnc":{"alias_symbol":["TGAM77","CNIL"],"prev_symbol":["CNIH"]},"alphafold":{"accession":"O95406","domains":[{"cath_id":"1.20.120","chopping":"4-142","consensus_level":"high","plddt":85.0004,"start":4,"end":142}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O95406","model_url":"https://alphafold.ebi.ac.uk/files/AF-O95406-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O95406-F1-predicted_aligned_error_v6.png","plddt_mean":84.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CNIH1","jax_strain_url":"https://www.jax.org/strain/search?query=CNIH1"},"sequence":{"accession":"O95406","fasta_url":"https://rest.uniprot.org/uniprotkb/O95406.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O95406/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O95406"}},"corpus_meta":[{"pmid":"21172611","id":"PMC_21172611","title":"Hippocampal AMPA receptor 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(CNIH) localizes primarily to the endoplasmic reticulum, associates with immature TGFα family proteins, and functions as a cargo receptor required for their transport, processing, and secretion; increased CNIH expression retains TGFα proteins in the ER, while loss of CNIH impairs their transport and secretion. Human CNIH complements loss of yeast Erv14 in axial budding.\",\n      \"method\": \"Subcellular fractionation, co-immunoprecipitation, complementation assay in yeast (Erv14 deletion), overexpression and knockdown in mammalian cells with secretion/processing readouts\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal functional assays (yeast complementation + mammalian gain/loss-of-function), multiple orthogonal methods, replicated across species\",\n      \"pmids\": [\"17607000\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"CNIH1 acts as a cargo receptor for proTGFα in COPII-mediated ER export. In a CNIH1-knockout HeLa cell line generated by CRISPR/Cas9, proTGFα packaging into COPII vesicles is severely impaired. Cell-free assays show that both CNIH1 and auxiliary cytosolic factor(s) are required for efficient recruitment of proTGFα to the COPII coat, and that cargo recruitment precedes and may be mechanistically distinct from subsequent packaging into COPII vesicles.\",\n      \"method\": \"CRISPR/Cas9 knockout, cell-free COPII vesicle budding assay, in vitro reconstitution of cargo recruitment to COPII coat\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — cell-free reconstitution assay plus clean genetic knockout with functional readout, single lab but two orthogonal methods\",\n      \"pmids\": [\"27122606\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CNIH1 is identified by a genome-wide CRISPR/Cas9 screen as a dedicated ER-to-PM export factor for the δ-opioid receptor (DOR) and a subset of class A GPCRs. In CNIH1-deficient cells, DOR is retained intracellularly with immature glycosylation and shows reduced plasma-membrane signaling. CNIH1 localizes to ER exit sites and the Golgi, directly interacts with opioid receptors, and requires its putative COPII-binding site for GPCR export. CNIH1 is functionally distinct from other human cornichon homologs in this selective GPCR-sorting role.\",\n      \"method\": \"Genome-wide CRISPR/Cas9 screen, synchronized cargo-release assay, co-immunoprecipitation (direct interaction), glycosylation analysis, CNIH1 knockout/knockdown with PM signaling readout, subcellular localization by imaging, COPII-binding site mutagenesis\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (screen + co-IP + mutagenesis + localization), single lab, preprint not yet peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2025.10.27.684930\"],\n      \"is_preprint\": true\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"CNIH1 physically binds to AMPA receptors via conserved membrane-proximal residues shared with CNIH-2/3, but modulates AMPAR gating at significantly lower magnitude than CNIH-3 because it lacks extracellular loop residues present in CNIH-2/3 that are critical for both AMPAR interaction and gating modulation. Thus CNIH1 binding to AMPARs can be dissociated from functional gating modulation.\",\n      \"method\": \"Peptide array-based screening, in vitro mutagenesis, single-particle electron microscopy of AMPAR-CNIH complexes, electrophysiology in heterologous cells\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro mutagenesis combined with structural (EM) and functional (electrophysiology) readouts, single lab but multiple orthogonal methods\",\n      \"pmids\": [\"25186755\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"CNIH-1 does not slow deactivation or desensitization of GluA2-containing or calcium-permeable AMPARs expressed in tsA201 cells, in contrast to CNIH-2 and CNIH-3, establishing that CNIH1 lacks the functional gating-modulatory activity of its paralogs on AMPARs.\",\n      \"method\": \"Heterologous expression in tsA201 cells, whole-cell patch-clamp electrophysiology\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean electrophysiological assay in recombinant system; negative result for CNIH1 gating modulation, single lab\",\n      \"pmids\": [\"22815494\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Mouse Cnih (ortholog of CNIH1) mRNA is a maternal transcript highly abundant in full-grown oocytes and ovulated unfertilized eggs, with specific localization to ovarian oocytes by in situ hybridization. The transcript lacks cytoplasmic polyadenylation elements, suggesting translation occurs in the full-grown oocyte before ovulation but not after. The gene maps to mouse chromosome 10.\",\n      \"method\": \"EST identification, Northern blot, RT-PCR, in situ hybridization, genetic mapping\",\n      \"journal\": \"Development genes and evolution\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct localization by in situ hybridization with RNA-level functional inference (polyadenylation analysis), multiple complementary methods, single lab\",\n      \"pmids\": [\"10022955\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Human CNIH1, CNIH2, and CNIH4 expressed in S. cerevisiae (replacing endogenous Erv14) support plasma-membrane targeting and functioning of the human Na+/H+ antiporter NHA2, identifying NHA2 as a novel cargo of cornichon COPII cargo receptors. CNIH1 (along with other human CNIHs) functionally complements yeast Erv14 phenotypes related to monovalent-cation homeostasis.\",\n      \"method\": \"Yeast complementation assay (ERV14 replacement), functional ion transport assays, plasma-membrane targeting analysis\",\n      \"journal\": \"Protein science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic complementation with functional readout in yeast, single lab, single publication\",\n      \"pmids\": [\"41676957\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CNIH1 (also known as TGAM77/CNIH) is a conserved ER-resident transmembrane protein that functions as a COPII cargo receptor: it associates with TGFα family precursors in the ER, promotes their ER exit and secretion, physically interacts with opioid and other class A GPCRs to drive their anterograde ER-to-plasma-membrane transport via a COPII-binding mechanism, and can also traffic the Na+/H+ antiporter NHA2; although CNIH1 physically binds AMPA receptor subunits via conserved membrane-proximal residues, it lacks the extracellular loop elements of CNIH-2/3 required for robust AMPAR gating modulation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CNIH1 is a conserved endoplasmic reticulum-resident cornichon-family protein that functions as a COPII cargo receptor, selecting specific membrane-associated cargoes for ER export and onward secretion or surface delivery [#0, #1]. It localizes primarily to the ER and ER exit sites, associates with immature TGF\\u03b1 family precursors, and is required for their transport, processing, and secretion; its expression level tunes cargo retention versus export, and it functionally substitutes for yeast Erv14 [#0]. Mechanistically, CNIH1 recruits proTGF\\u03b1 to the COPII coat in concert with auxiliary cytosolic factors, a recruitment step that precedes and is distinguishable from packaging into COPII vesicles [#1]. Beyond TGF\\u03b1, CNIH1 acts as a selective ER-to-plasma-membrane export factor for the \\u03b4-opioid receptor and a subset of class A GPCRs, directly binding these receptors and requiring its COPII-binding site for their anterograde trafficking [#2], and it can also support surface targeting of the Na+/H+ antiporter NHA2 [#6]. Although CNIH1 physically binds AMPA receptor subunits through conserved membrane-proximal residues, it lacks the extracellular loop elements present in CNIH-2/3 and therefore does not confer the AMPAR gating modulation characteristic of its paralogs, dissociating receptor binding from functional gating control [#3, #4].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Established the earliest expression context for the mammalian cornichon ortholog, showing it is a maternally deposited oocyte transcript before any molecular function was known.\",\n      \"evidence\": \"EST identification, Northern blot, in situ hybridization and genetic mapping of mouse Cnih\",\n      \"pmids\": [\"10022955\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No protein-level function assigned\", \"Cargo receptor role not yet identified\", \"Relevance of oocyte expression to trafficking function unaddressed\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Defined CNIH1 as an ER cargo receptor by showing it associates with immature TGF\\u03b1 precursors and controls their transport and secretion, with cross-species rescue of yeast Erv14.\",\n      \"evidence\": \"Subcellular fractionation, co-IP, yeast Erv14 complementation, and gain/loss-of-function in mammalian cells with secretion readouts\",\n      \"pmids\": [\"17607000\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not define the COPII-coat interaction biochemically\", \"Cargo specificity beyond TGF\\u03b1 family unknown\", \"Step at which CNIH1 acts in COPII budding not resolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Resolved where CNIH1 acts in the export pathway, showing it is required to recruit proTGF\\u03b1 to the COPII coat as a step distinct from vesicle packaging, with auxiliary cytosolic factors.\",\n      \"evidence\": \"CRISPR/Cas9 knockout in HeLa, cell-free COPII budding assay, and in vitro reconstitution of cargo recruitment\",\n      \"pmids\": [\"27122606\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of auxiliary cytosolic factor(s) not determined\", \"Direct CNIH1-COPII contact residues not mapped here\", \"Mechanistic separation of recruitment vs packaging not structurally defined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Determined that CNIH1 binds AMPA receptors but cannot modulate their gating, localizing the gating-modulatory determinants to paralog-specific extracellular loop residues absent in CNIH1.\",\n      \"evidence\": \"Peptide array screening, mutagenesis, single-particle EM of AMPAR-CNIH complexes, and electrophysiology in heterologous cells\",\n      \"pmids\": [\"25186755\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological significance of CNIH1-AMPAR binding without gating effect unclear\", \"Whether CNIH1 traffics AMPARs in neurons not tested\", \"No endogenous neuronal validation\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Provided the functional negative control distinguishing CNIH1 from its paralogs, confirming it does not slow AMPAR deactivation or desensitization.\",\n      \"evidence\": \"Heterologous expression in tsA201 cells with whole-cell patch-clamp electrophysiology\",\n      \"pmids\": [\"22815494\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Negative result in recombinant system only\", \"Does not address CNIH1 binding to AMPARs\", \"Single lab\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Broadened CNIH1's cargo repertoire to GPCRs, identifying it as a selective ER-to-PM export factor for the \\u03b4-opioid receptor and a subset of class A GPCRs that requires its COPII-binding site.\",\n      \"evidence\": \"Genome-wide CRISPR screen, synchronized cargo-release assay, co-IP, glycosylation analysis, localization imaging and COPII-binding-site mutagenesis (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.10.27.684930\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Preprint, not yet peer-reviewed\", \"Determinants of GPCR cargo selectivity not defined\", \"In vivo physiological role in opioid signaling untested\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Extended CNIH1 cargo range to an ion transporter, showing it supports plasma-membrane targeting and function of the Na+/H+ antiporter NHA2.\",\n      \"evidence\": \"Yeast Erv14-replacement complementation with functional ion transport and PM-targeting assays\",\n      \"pmids\": [\"41676957\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Demonstrated in yeast surrogate rather than native mammalian cells\", \"Direct CNIH1-NHA2 interaction not shown\", \"Specificity versus other human cornichons not dissected\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How CNIH1 achieves cargo selectivity across structurally diverse clients (TGF\\u03b1 precursors, class A GPCRs, ion transporters) and what cytosolic cofactors and COPII contacts govern recruitment remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying cargo recognition determinant identified\", \"Auxiliary cytosolic factor(s) uncharacterized\", \"No high-resolution structure of CNIH1-cargo or CNIH1-COPII complex\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0038024\", \"supporting_discovery_ids\": [0, 1, 2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [1, 2]}\n    ],\n    \"complexes\": [\"COPII coat\"],\n    \"partners\": [\"TGFA\", \"OPRD1\", \"NHA2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"tie","faith_supported":5,"faith_total":5,"faith_pct":100.0}}