{"gene":"TOMT","run_date":"2026-04-28T21:42:59","timeline":{"discoveries":[{"year":2008,"finding":"LRTOMT encodes two proteins via alternative reading frames: LRTOMT1 and LRTOMT2 (a putative methyltransferase), and mutations in LRTOMT cause profound nonsyndromic hearing loss (DFNB63). In the primate lineage, LRTOMT evolved from the fusion of two ancestral genes (Lrrc51 and Tomt) that exist as separate genes in rodents.","method":"Positional cloning, protein blot analysis, comparative genomics","journal":"Nature genetics","confidence":"High","confidence_rationale":"Tier 2 — positional cloning with protein-level validation, replicated across human families","pmids":["18953341"],"is_preprint":false},{"year":2008,"finding":"TOMT (designated COMT2 in mice) encodes a catechol-O-methyltransferase expressed in sensory hair cells of the inner ear; a missense mutation significantly reduces COMT2 enzymatic activity and causes vestibular impairment, profound sensorineural deafness, and progressive degeneration of the organ of Corti in mice, and a human nonsense mutation in its ortholog causes nonsyndromic deafness.","method":"Positional cloning of chemically induced mutation, enzymatic activity assay, human genetic screening","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1-2 — enzymatic assay combined with mouse genetics and human mutation validation","pmids":["18794526"],"is_preprint":false},{"year":2017,"finding":"TOMT is essential for mechanotransduction (MET) in hair cells; in tomt-deficient zebrafish, Tmc1/2 proteins are specifically excluded from the hair bundle while other MET complex proteins localize normally. GFP-tagged Tomt is enriched in the Golgi, and mouse TOMT and TMC1 directly interact in HEK 293 cells, with interaction modulated by His183 in TOMT, indicating TOMT traffics TMC proteins through the secretory pathway to the hair bundle.","method":"Zebrafish loss-of-function model, live-cell fluorescence imaging (GFP-Tomt), co-immunoprecipitation in HEK 293 cells, site-directed mutagenesis (His183), electrophysiology (MET recording)","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (imaging, co-IP, mutagenesis, electrophysiology) in single rigorous study","pmids":["28534737"],"is_preprint":false},{"year":2017,"finding":"mTOMT (murine TOMT/COMT2) is essential for mechanotransduction in cochlear hair cells through a mechanism independent of its methyltransferase activity; mCOMT cannot substitute for mTOMT function. mTOMT binds putative mechanotransduction channel components and is required for their transport into stereocilia, indicating functional diversification between mCOMT and mTOMT.","method":"Conditional knockout mouse, electrophysiology (mechanotransduction currents), co-immunoprecipitation, methyltransferase activity assays with rescue experiments","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1-2 — KO mouse with defined cellular phenotype, biochemical binding assay, and functional rescue experiments","pmids":["28504928"],"is_preprint":false}],"current_model":"TOMT (LRTOMT2 in humans) is a catechol-O-methyltransferase expressed in inner ear sensory hair cells that localizes to the Golgi and functions—independently of its methyltransferase catalytic activity—to directly bind TMC1/2 proteins and traffic them through the secretory pathway into the mechanosensitive stereocilia hair bundle, thereby enabling assembly of the mechanotransduction channel complex; loss of TOMT causes selective exclusion of TMC1/2 from the bundle, abolishes mechanotransduction, and results in nonsyndromic sensorineural deafness (DFNB63)."},"narrative":{"teleology":[{"year":2008,"claim":"Identification of TOMT/LRTOMT as a deafness gene established that a catechol-O-methyltransferase–domain protein is required for auditory and vestibular function, and that the human gene arose from a primate-lineage fusion of two ancestral loci (Lrrc51 and Tomt).","evidence":"Positional cloning of DFNB63 families and of a chemically induced mouse mutant, combined with enzymatic activity assays and comparative genomics","pmids":["18953341","18794526"],"confidence":"High","gaps":["Whether the methyltransferase activity itself is the functionally relevant mechanism was not resolved","The specific molecular partners of TOMT in hair cells were unknown","Subcellular site of TOMT action in hair cells was not determined"]},{"year":2017,"claim":"Two independent studies resolved the mechanism: TOMT localizes to the Golgi, directly binds TMC1/2, and acts as a trafficking chaperone that delivers TMC proteins to stereocilia—independently of methyltransferase catalytic activity—thereby enabling mechanotransduction channel function.","evidence":"Zebrafish loss-of-function and conditional knockout mouse models combined with live-cell GFP imaging, co-immunoprecipitation in HEK 293 cells, site-directed mutagenesis of His183, electrophysiology of mechanotransduction currents, and rescue experiments with catalytically inactive TOMT versus COMT","pmids":["28534737","28504928"],"confidence":"High","gaps":["Structural basis of the TOMT–TMC interaction and the role of His183 remain undefined","Whether TOMT traffics additional cargo beyond TMC1/2 is unknown","The mechanism by which TOMT selectively recognizes TMC proteins over other stereocilia proteins has not been determined"]},{"year":null,"claim":"It remains unresolved how TOMT distinguishes TMC1/2 from other membrane proteins in the secretory pathway, what structural features mediate the interaction, and whether TOMT serves additional roles in the hair cell beyond TMC trafficking.","evidence":"","pmids":[],"confidence":"High","gaps":["No structural model of the TOMT–TMC complex exists","Post-Golgi trafficking route from TOMT handoff to stereocilia insertion is uncharacterized","Potential non-hair-cell functions of TOMT have not been investigated"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[1]},{"term_id":"GO:0044183","term_label":"protein folding chaperone","supporting_discovery_ids":[2,3]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[2]}],"pathway":[{"term_id":"R-HSA-9709957","term_label":"Sensory Perception","supporting_discovery_ids":[0,1]}],"complexes":[],"partners":["TMC1","TMC2"],"other_free_text":[]},"mechanistic_narrative":"TOMT (LRTOMT2 in humans; also called COMT2 in mice) is an inner-ear hair-cell protein that, despite possessing catechol-O-methyltransferase activity, functions independently of its enzymatic activity to traffic the mechanotransduction channel subunits TMC1 and TMC2 from the Golgi through the secretory pathway into stereocilia, thereby enabling assembly of a functional mechanotransduction complex [PMID:28534737, PMID:28504928]. TOMT directly binds TMC1 via an interaction modulated by His183, and its loss selectively excludes TMC1/2 from the hair bundle while leaving other mechanotransduction complex components correctly localized, abolishing mechanotransduction currents [PMID:28534737, PMID:28504928]. Mutations in the human ortholog LRTOMT—a primate-specific fusion gene encoding LRTOMT2—cause profound nonsyndromic sensorineural deafness DFNB63 [PMID:18953341, PMID:18794526]."},"prefetch_data":{"uniprot":{"accession":"Q8WZ04","full_name":"Transmembrane O-methyltransferase","aliases":["Catechol O-methyltransferase 2","Protein LRTOMT2"],"length_aa":291,"mass_kda":32.2,"function":"Catalyzes the O-methylation, and thereby the inactivation, of catecholamine neurotransmitters and catechol hormones (By similarity). Required for auditory function (PubMed:18794526). Component of the cochlear hair cell's mechanotransduction (MET) machinery. Involved in the assembly of the asymmetric tip-link MET complex. Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia of the hair cells. The function in MET is independent of the enzymatic activity (By similarity)","subcellular_location":"Cytoplasm; Endoplasmic reticulum","url":"https://www.uniprot.org/uniprotkb/Q8WZ04/entry"},"depmap":{"release":"DepMap","has_data":false,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TOMT"},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/TOMT","total_profiled":1310},"omim":[{"mim_id":"612414","title":"LEUCINE-RICH TRANSMEMBRANE O-METHYLTRANSFERASE; LRTOMT","url":"https://www.omim.org/entry/612414"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Not detected","tissue_distribution":"Not detected","driving_tissues":[],"url":"https://www.proteinatlas.org/search/TOMT"},"hgnc":{"alias_symbol":["COMT2"],"prev_symbol":[]},"alphafold":{"accession":"Q8WZ04","domains":[{"cath_id":"3.40.50.150","chopping":"116-288","consensus_level":"high","plddt":97.4943,"start":116,"end":288}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8WZ04","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8WZ04-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8WZ04-F1-predicted_aligned_error_v6.png","plddt_mean":90.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TOMT","jax_strain_url":"https://www.jax.org/strain/search?query=TOMT"},"sequence":{"accession":"Q8WZ04","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8WZ04.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8WZ04/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8WZ04"}},"corpus_meta":[{"pmid":"26811086","id":"PMC_26811086","title":"Lignin biosynthesis in wheat (Triticum aestivum L.): its response to waterlogging and association with hormonal levels.","date":"2016","source":"BMC plant biology","url":"https://pubmed.ncbi.nlm.nih.gov/26811086","citation_count":70,"is_preprint":false},{"pmid":"18953341","id":"PMC_18953341","title":"Mutations of LRTOMT, a fusion gene with alternative reading frames, cause nonsyndromic deafness in humans.","date":"2008","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/18953341","citation_count":56,"is_preprint":false},{"pmid":"18794526","id":"PMC_18794526","title":"A catechol-O-methyltransferase that is essential for auditory function in mice and humans.","date":"2008","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/18794526","citation_count":53,"is_preprint":false},{"pmid":"28534737","id":"PMC_28534737","title":"Integration of Tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by Transmembrane O-methyltransferase (Tomt).","date":"2017","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/28534737","citation_count":50,"is_preprint":false},{"pmid":"28504928","id":"PMC_28504928","title":"The murine catecholamine methyltransferase mTOMT is essential for mechanotransduction by cochlear hair cells.","date":"2017","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/28504928","citation_count":29,"is_preprint":false},{"pmid":"28031745","id":"PMC_28031745","title":"RNAi downregulation of three key lignin genes in sugarcane improves glucose release without reduction in sugar production.","date":"2016","source":"Biotechnology for biofuels","url":"https://pubmed.ncbi.nlm.nih.gov/28031745","citation_count":26,"is_preprint":false},{"pmid":"32507983","id":"PMC_32507983","title":"Genotoxic effects and proteomic analysis on Allium cepa var. agrogarum L. root cells under Pb stress.","date":"2020","source":"Ecotoxicology (London, England)","url":"https://pubmed.ncbi.nlm.nih.gov/32507983","citation_count":14,"is_preprint":false},{"pmid":"21767344","id":"PMC_21767344","title":"Transcript Accumulation Dynamics of Phenylpropanoid Pathway Genes in the Maturing Xylem and Phloem of Picea abies during Latewood Formation.","date":"2011","source":"Journal of integrative plant biology","url":"https://pubmed.ncbi.nlm.nih.gov/21767344","citation_count":6,"is_preprint":false},{"pmid":"31053915","id":"PMC_31053915","title":"Catechol O-methyltransferase homologs in Schizosaccharomyces pombe are response factors to alkaline and salt stress.","date":"2019","source":"Applied microbiology and biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/31053915","citation_count":4,"is_preprint":false},{"pmid":"40573727","id":"PMC_40573727","title":"The Fiber Cell-Specific Overexpression of COMT2 Modulates Secondary Cell Wall Biosynthesis in Poplar.","date":"2025","source":"Plants (Basel, Switzerland)","url":"https://pubmed.ncbi.nlm.nih.gov/40573727","citation_count":1,"is_preprint":false},{"pmid":"39859384","id":"PMC_39859384","title":"Integrated Metabolome, Transcriptome, and Physiological Analysis of the Flavonoid and Phenylethanol Glycosides Accumulation in Wild Phlomoides rotata Roots from Different Habitats.","date":"2025","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/39859384","citation_count":1,"is_preprint":false},{"pmid":"31637134","id":"PMC_31637134","title":"Effects of field-grown transgenic switchgrass carbon inputs on soil organic carbon cycling.","date":"2019","source":"PeerJ","url":"https://pubmed.ncbi.nlm.nih.gov/31637134","citation_count":1,"is_preprint":false},{"pmid":"37908103","id":"PMC_37908103","title":"Evaluation of Comt2, Comt3, Cyp1b1, and Esr1 gene polymorphisms as risk factor for endometrial polyp.","date":"2023","source":"Women & health","url":"https://pubmed.ncbi.nlm.nih.gov/37908103","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7738,"output_tokens":1146,"usd":0.020202},"stage2":{"model":"claude-opus-4-6","input_tokens":4350,"output_tokens":2383,"usd":0.121987},"total_usd":0.142189,"stage1_batch_id":"msgbatch_01RPbVc9PDH9zQmYK5Hs6srm","stage2_batch_id":"msgbatch_01JVbVLzeKN2yVrsGp3zC8aM","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2008,\n      \"finding\": \"LRTOMT encodes two proteins via alternative reading frames: LRTOMT1 and LRTOMT2 (a putative methyltransferase), and mutations in LRTOMT cause profound nonsyndromic hearing loss (DFNB63). In the primate lineage, LRTOMT evolved from the fusion of two ancestral genes (Lrrc51 and Tomt) that exist as separate genes in rodents.\",\n      \"method\": \"Positional cloning, protein blot analysis, comparative genomics\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — positional cloning with protein-level validation, replicated across human families\",\n      \"pmids\": [\"18953341\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"TOMT (designated COMT2 in mice) encodes a catechol-O-methyltransferase expressed in sensory hair cells of the inner ear; a missense mutation significantly reduces COMT2 enzymatic activity and causes vestibular impairment, profound sensorineural deafness, and progressive degeneration of the organ of Corti in mice, and a human nonsense mutation in its ortholog causes nonsyndromic deafness.\",\n      \"method\": \"Positional cloning of chemically induced mutation, enzymatic activity assay, human genetic screening\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — enzymatic assay combined with mouse genetics and human mutation validation\",\n      \"pmids\": [\"18794526\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"TOMT is essential for mechanotransduction (MET) in hair cells; in tomt-deficient zebrafish, Tmc1/2 proteins are specifically excluded from the hair bundle while other MET complex proteins localize normally. GFP-tagged Tomt is enriched in the Golgi, and mouse TOMT and TMC1 directly interact in HEK 293 cells, with interaction modulated by His183 in TOMT, indicating TOMT traffics TMC proteins through the secretory pathway to the hair bundle.\",\n      \"method\": \"Zebrafish loss-of-function model, live-cell fluorescence imaging (GFP-Tomt), co-immunoprecipitation in HEK 293 cells, site-directed mutagenesis (His183), electrophysiology (MET recording)\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (imaging, co-IP, mutagenesis, electrophysiology) in single rigorous study\",\n      \"pmids\": [\"28534737\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"mTOMT (murine TOMT/COMT2) is essential for mechanotransduction in cochlear hair cells through a mechanism independent of its methyltransferase activity; mCOMT cannot substitute for mTOMT function. mTOMT binds putative mechanotransduction channel components and is required for their transport into stereocilia, indicating functional diversification between mCOMT and mTOMT.\",\n      \"method\": \"Conditional knockout mouse, electrophysiology (mechanotransduction currents), co-immunoprecipitation, methyltransferase activity assays with rescue experiments\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — KO mouse with defined cellular phenotype, biochemical binding assay, and functional rescue experiments\",\n      \"pmids\": [\"28504928\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TOMT (LRTOMT2 in humans) is a catechol-O-methyltransferase expressed in inner ear sensory hair cells that localizes to the Golgi and functions—independently of its methyltransferase catalytic activity—to directly bind TMC1/2 proteins and traffic them through the secretory pathway into the mechanosensitive stereocilia hair bundle, thereby enabling assembly of the mechanotransduction channel complex; loss of TOMT causes selective exclusion of TMC1/2 from the bundle, abolishes mechanotransduction, and results in nonsyndromic sensorineural deafness (DFNB63).\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"TOMT (LRTOMT2 in humans; also called COMT2 in mice) is an inner-ear hair-cell protein that, despite possessing catechol-O-methyltransferase activity, functions independently of its enzymatic activity to traffic the mechanotransduction channel subunits TMC1 and TMC2 from the Golgi through the secretory pathway into stereocilia, thereby enabling assembly of a functional mechanotransduction complex [PMID:28534737, PMID:28504928]. TOMT directly binds TMC1 via an interaction modulated by His183, and its loss selectively excludes TMC1/2 from the hair bundle while leaving other mechanotransduction complex components correctly localized, abolishing mechanotransduction currents [PMID:28534737, PMID:28504928]. Mutations in the human ortholog LRTOMT—a primate-specific fusion gene encoding LRTOMT2—cause profound nonsyndromic sensorineural deafness DFNB63 [PMID:18953341, PMID:18794526].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Identification of TOMT/LRTOMT as a deafness gene established that a catechol-O-methyltransferase–domain protein is required for auditory and vestibular function, and that the human gene arose from a primate-lineage fusion of two ancestral loci (Lrrc51 and Tomt).\",\n      \"evidence\": \"Positional cloning of DFNB63 families and of a chemically induced mouse mutant, combined with enzymatic activity assays and comparative genomics\",\n      \"pmids\": [\"18953341\", \"18794526\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether the methyltransferase activity itself is the functionally relevant mechanism was not resolved\",\n        \"The specific molecular partners of TOMT in hair cells were unknown\",\n        \"Subcellular site of TOMT action in hair cells was not determined\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Two independent studies resolved the mechanism: TOMT localizes to the Golgi, directly binds TMC1/2, and acts as a trafficking chaperone that delivers TMC proteins to stereocilia—independently of methyltransferase catalytic activity—thereby enabling mechanotransduction channel function.\",\n      \"evidence\": \"Zebrafish loss-of-function and conditional knockout mouse models combined with live-cell GFP imaging, co-immunoprecipitation in HEK 293 cells, site-directed mutagenesis of His183, electrophysiology of mechanotransduction currents, and rescue experiments with catalytically inactive TOMT versus COMT\",\n      \"pmids\": [\"28534737\", \"28504928\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis of the TOMT–TMC interaction and the role of His183 remain undefined\",\n        \"Whether TOMT traffics additional cargo beyond TMC1/2 is unknown\",\n        \"The mechanism by which TOMT selectively recognizes TMC proteins over other stereocilia proteins has not been determined\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how TOMT distinguishes TMC1/2 from other membrane proteins in the secretory pathway, what structural features mediate the interaction, and whether TOMT serves additional roles in the hair cell beyond TMC trafficking.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No structural model of the TOMT–TMC complex exists\",\n        \"Post-Golgi trafficking route from TOMT handoff to stereocilia insertion is uncharacterized\",\n        \"Potential non-hair-cell functions of TOMT have not been investigated\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0044183\", \"supporting_discovery_ids\": [2, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0009609507\", \"supporting_discovery_ids\": [2, 3]},\n      {\"term_id\": \"R-HSA-9709957\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"TMC1\", \"TMC2\"],\n    \"other_free_text\": []\n  }\n}\n```\n\nWait, I made an error in the pathway term_id. Let me fix that — I accidentally used a GO term format for a Reactome pathway. Let me correct:\n\n```json\n{\n  \"mechanistic_narrative\": \"TOMT (LRTOMT2 in humans; also called COMT2 in mice) is an inner-ear hair-cell protein that, despite possessing catechol-O-methyltransferase activity, functions independently of its enzymatic activity to traffic the mechanotransduction channel subunits TMC1 and TMC2 from the Golgi through the secretory pathway into stereocilia, thereby enabling assembly of a functional mechanotransduction complex [PMID:28534737, PMID:28504928]. TOMT directly binds TMC1 via an interaction modulated by His183, and its loss selectively excludes TMC1/2 from the hair bundle while leaving other mechanotransduction complex components correctly localized, abolishing mechanotransduction currents [PMID:28534737, PMID:28504928]. Mutations in the human ortholog LRTOMT—a primate-specific fusion gene encoding LRTOMT2—cause profound nonsyndromic sensorineural deafness DFNB63 [PMID:18953341, PMID:18794526].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Identification of TOMT/LRTOMT as a deafness gene established that a catechol-O-methyltransferase–domain protein is required for auditory and vestibular function, and that the human gene arose from a primate-lineage fusion of two ancestral loci (Lrrc51 and Tomt).\",\n      \"evidence\": \"Positional cloning of DFNB63 families and of a chemically induced mouse mutant, combined with enzymatic activity assays and comparative genomics\",\n      \"pmids\": [\"18953341\", \"18794526\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Whether the methyltransferase activity itself is the functionally relevant mechanism was not resolved\",\n        \"The specific molecular partners of TOMT in hair cells were unknown\",\n        \"Subcellular site of TOMT action in hair cells was not determined\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Two independent studies resolved the mechanism: TOMT localizes to the Golgi, directly binds TMC1/2, and acts as a trafficking chaperone that delivers TMC proteins to stereocilia—independently of methyltransferase catalytic activity—thereby enabling mechanotransduction channel function.\",\n      \"evidence\": \"Zebrafish loss-of-function and conditional knockout mouse models combined with live-cell GFP imaging, co-immunoprecipitation in HEK 293 cells, site-directed mutagenesis of His183, electrophysiology of mechanotransduction currents, and rescue experiments with catalytically inactive TOMT versus COMT\",\n      \"pmids\": [\"28534737\", \"28504928\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis of the TOMT–TMC interaction and the role of His183 remain undefined\",\n        \"Whether TOMT traffics additional cargo beyond TMC1/2 is unknown\",\n        \"The mechanism by which TOMT selectively recognizes TMC proteins over other stereocilia proteins has not been determined\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how TOMT distinguishes TMC1/2 from other membrane proteins in the secretory pathway, what structural features mediate the interaction, and whether TOMT serves additional roles in the hair cell beyond TMC trafficking.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"No structural model of the TOMT–TMC complex exists\",\n        \"Post-Golgi trafficking route from TOMT handoff to stereocilia insertion is uncharacterized\",\n        \"Potential non-hair-cell functions of TOMT have not been investigated\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0044183\", \"supporting_discovery_ids\": [2, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [2, 3]},\n      {\"term_id\": \"R-HSA-9709957\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"TMC1\", \"TMC2\"],\n    \"other_free_text\": []\n  }\n}\n```"}