Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0032502 developmental process	IBA GO_REF:0000033	MARK AS OVER ANNOTATED	Summary: developmental process (GO:0032502) likely overstates or misdirects the direct function of tomt. Reason: The evidence is better explained by the gene core function (selective Tmc trafficking for mechanotransduction) than by a general developmental role. Falcon shows the tomt loss-of-function phenotype is a specific MET defect, with other hair-cell properties retained, rather than a broad developmental failure. Supporting Evidence: file:DANRE/tomt/tomt-uniprot.txt Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia PMID:28534737 Tomt is required for trafficking Tmc proteins to the hair bundle file:DANRE/tomt/tomt-deep-research-falcon.md consistent with a specific MET defect rather than general hair-cell loss
GO:0016206 catechol O-methyltransferase activity	IBA GO_REF:0000033	KEEP AS NON CORE	Summary: catechol O-methyltransferase activity (GO:0016206) is retained as supported context for tomt but is not the primary/core function. Reason: The SAM-dependent methyltransferase fold is genuinely present and the methyltransferase-like region is required for rescue, so this molecular function is plausible by-similarity context. However, falcon shows the physiological role in MET is independent of canonical catechol-O-methyltransferase catalysis and the endogenous methyl-acceptor substrate is unknown, so this term is non-core. Supporting Evidence: file:DANRE/tomt/tomt-uniprot.txt Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia PMID:28534737 His183 in the putative active site of TOMT file:DANRE/tomt/tomt-deep-research-falcon.md its physiological methyl-acceptor substrate remains unknown file:DANRE/tomt/tomt-deep-research-falcon.md the transmembrane domain and the enzymatic (methyltransferase-like) region are required for full rescue
GO:0042417 dopamine metabolic process	IBA GO_REF:0000033	MARK AS OVER ANNOTATED	Summary: dopamine metabolic process (GO:0042417) is likely an over-annotation of tomt based on family/sequence similarity, not the physiological function. Reason: This is a phylogenetic/by-similarity transfer from COMT-like enzymes. Falcon shows several results argue against a simple catecholamine-metabolism function for Tomt (COMT cannot rescue tomt mutants, only modest in vitro activity, active-site H183A still rescues), and no dopamine-metabolism role is demonstrated in zebrafish hair cells. Supporting Evidence: file:DANRE/tomt/tomt-uniprot.txt Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia PMID:28534737 Mechanotransduction in mercury mutants can be rescued by transgenic expression of either zebrafish Tomt or mouse TOMT, but not with the closely related Comt enzyme file:DANRE/tomt/tomt-deep-research-falcon.md several results argue against a simple catecholamine-metabolism function
GO:0042424 catecholamine catabolic process	IBA GO_REF:0000033	MARK AS OVER ANNOTATED	Summary: catecholamine catabolic process (GO:0042424) is likely an over-annotation of tomt based on family/sequence similarity, not the physiological function. Reason: This is a by-similarity transfer from COMT-like enzymes. Falcon shows the data argue against a simple catecholamine-metabolism function, including that COMT cannot rescue tomt mutants and an active-site histidine mutation still supports rescue; no catecholamine catabolism role is demonstrated for zebrafish Tomt. Supporting Evidence: file:DANRE/tomt/tomt-uniprot.txt Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia PMID:28534737 Mechanotransduction in mercury mutants can be rescued by transgenic expression of either zebrafish Tomt or mouse TOMT, but not with the closely related Comt enzyme file:DANRE/tomt/tomt-deep-research-falcon.md COMT cannot rescue tomt mutants, TOMT has only modest activity toward norepinephrine in vitro, and an active-site histidine mutation (H183A) can still support rescue in vivo
GO:0005783 endoplasmic reticulum	IEA GO_REF:0000044	ACCEPT	Summary: endoplasmic reticulum (GO:0005783) is supported for tomt. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: file:DANRE/tomt/tomt-uniprot.txt Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia PMID:28534737 Tomt-GFP may be present at lower levels in the endoplasmic reticulum and the basolateral membrane in addition to the Golgi apparatus file:DANRE/tomt/tomt-deep-research-falcon.md TOMT is localized to the ER/secretory pathway and is required for TMC1 transport into stereocilia
GO:0005794 Golgi apparatus	IEA GO_REF:0000044	ACCEPT	Summary: Golgi apparatus (GO:0005794) is supported for tomt. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: file:DANRE/tomt/tomt-uniprot.txt Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia PMID:28534737 Tomt-GFP and Mgat1a_1-110-mKate2 are partially co-localized in hair cells file:DANRE/tomt/tomt-deep-research-falcon.md GFP-tagged Tomt is enriched in the Golgi and excluded from stereociliary bundles
GO:0008171 O-methyltransferase activity	IEA GO_REF:0000002	KEEP AS NON CORE	Summary: O-methyltransferase activity (GO:0008171) is retained as supported context for tomt but is not the primary/core function. Reason: The predicted SAM-dependent methyltransferase domain is present and required for rescue, so this molecular function is plausible by-similarity context. Falcon shows the physiological MET role does not depend on canonical methyltransferase catalysis and no endogenous methyl-acceptor substrate is identified, so this term is non-core. Supporting Evidence: file:DANRE/tomt/tomt-uniprot.txt Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia PMID:28534737 His183 in the putative active site of TOMT file:DANRE/tomt/tomt-deep-research-falcon.md the transmembrane domain and the enzymatic (methyltransferase-like) region are required for full rescue
GO:0016206 catechol O-methyltransferase activity	IEA GO_REF:0000120	KEEP AS NON CORE	Summary: catechol O-methyltransferase activity (GO:0016206) is retained as supported context for tomt but is not the primary/core function. Reason: The SAM-dependent methyltransferase fold is genuinely present and the methyltransferase-like region is required for rescue, so this molecular function is plausible by-similarity context. However, falcon shows the physiological role in MET is independent of canonical catechol-O-methyltransferase catalysis and the endogenous methyl-acceptor substrate is unknown, so this term is non-core. Supporting Evidence: file:DANRE/tomt/tomt-uniprot.txt Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia PMID:28534737 His183 in the putative active site of TOMT file:DANRE/tomt/tomt-deep-research-falcon.md its physiological methyl-acceptor substrate remains unknown
GO:0016323 basolateral plasma membrane	IEA GO_REF:0000044	ACCEPT	Summary: basolateral plasma membrane (GO:0016323) is supported for tomt. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: file:DANRE/tomt/tomt-uniprot.txt Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia PMID:28534737 Tomt-GFP may be present at lower levels in the endoplasmic reticulum and the basolateral membrane in addition to the Golgi apparatus file:DANRE/tomt/tomt-deep-research-falcon.md functions primarily in the secretory pathway (Golgi/ER) to enable trafficking and bundle targeting of Tmc1/Tmc2 (MET channel subunits)
GO:0016206 catechol O-methyltransferase activity	ISS GO_REF:0000024	KEEP AS NON CORE	Summary: catechol O-methyltransferase activity (GO:0016206) is retained as supported context for tomt but is not the primary/core function. Reason: The SAM-dependent methyltransferase fold is genuinely present and the methyltransferase-like region is required for rescue, so this molecular function is plausible by-similarity context. However, falcon shows the physiological role in MET is independent of canonical catechol-O-methyltransferase catalysis and the endogenous methyl-acceptor substrate is unknown, so this term is non-core. Supporting Evidence: file:DANRE/tomt/tomt-uniprot.txt Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia PMID:28534737 His183 in the putative active site of TOMT file:DANRE/tomt/tomt-deep-research-falcon.md its physiological methyl-acceptor substrate remains unknown
GO:0005783 endoplasmic reticulum	IDA PMID:28534737 Integration of Tmc1/2 into the mechanotransduction complex i...	ACCEPT	Summary: endoplasmic reticulum (GO:0005783) is supported for tomt. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: PMID:28534737 Tomt-GFP may be present at lower levels in the endoplasmic reticulum and the basolateral membrane in addition to the Golgi apparatus file:DANRE/tomt/tomt-deep-research-falcon.md TOMT is localized to the ER/secretory pathway and is required for TMC1 transport into stereocilia
GO:0005794 Golgi apparatus	IDA PMID:28534737 Integration of Tmc1/2 into the mechanotransduction complex i...	ACCEPT	Summary: Golgi apparatus (GO:0005794) is supported for tomt. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: PMID:28534737 Tomt-GFP and Mgat1a_1-110-mKate2 are partially co-localized in hair cells file:DANRE/tomt/tomt-deep-research-falcon.md A functional Tomt-GFP fusion is reported to be enriched in the Golgi of zebrafish hair cells and excluded from the stereocilia bundle
GO:0016323 basolateral plasma membrane	IDA PMID:28534737 Integration of Tmc1/2 into the mechanotransduction complex i...	ACCEPT	Summary: basolateral plasma membrane (GO:0016323) is supported for tomt. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: PMID:28534737 Tomt-GFP may be present at lower levels in the endoplasmic reticulum and the basolateral membrane in addition to the Golgi apparatus file:DANRE/tomt/tomt-deep-research-falcon.md functions primarily in the secretory pathway (Golgi/ER) to enable trafficking and bundle targeting of Tmc1/Tmc2 (MET channel subunits)
GO:0031223 auditory behavior	IMP PMID:28534737 Integration of Tmc1/2 into the mechanotransduction complex i...	KEEP AS NON CORE	Summary: auditory behavior (GO:0031223) is a supported organism-level phenotype for tomt but is not a direct core gene function. Reason: Tomt directly supports hair-cell mechanotransduction-complex assembly and TMC trafficking; auditory behavior is a downstream systems-level phenotype. Supporting Evidence: PMID:28534737 non-transgenic mercury mutants exhibited a startle response to 2% of stimuli, confirming that Tomt-deficient zebrafish are deaf file:DANRE/tomt/tomt-deep-research-falcon.md mutants show auditory and vestibular phenotypes consistent with loss of sensory hair-cell function
GO:0042424 catecholamine catabolic process	ISS GO_REF:0000024	MARK AS OVER ANNOTATED	Summary: catecholamine catabolic process (GO:0042424) is likely an over-annotation of tomt based on family/sequence similarity, not the physiological function. Reason: This is a by-similarity transfer from COMT-like enzymes. Falcon shows the data argue against a simple catecholamine-metabolism function, including that COMT cannot rescue tomt mutants and an active-site histidine mutation still supports rescue; no catecholamine catabolism role is demonstrated for zebrafish Tomt. Supporting Evidence: file:DANRE/tomt/tomt-uniprot.txt Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia PMID:28534737 Mechanotransduction in mercury mutants can be rescued by transgenic expression of either zebrafish Tomt or mouse TOMT, but not with the closely related Comt enzyme file:DANRE/tomt/tomt-deep-research-falcon.md COMT cannot rescue tomt mutants, TOMT has only modest activity toward norepinephrine in vitro, and an active-site histidine mutation (H183A) can still support rescue in vivo
GO:0060122 inner ear receptor cell stereocilium organization	IMP PMID:28534737 Integration of Tmc1/2 into the mechanotransduction complex i...	ACCEPT	Summary: inner ear receptor cell stereocilium organization (GO:0060122) is supported for tomt. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: PMID:28534737 GFP-tagged Tmc1 and Tmc2b fail to localize to the hair bundle in mercury mutants file:DANRE/tomt/tomt-deep-research-falcon.md Tmc1-GFP and Tmc2b-GFP** are absent from bundles and remain in the cell body
GO:0006897 endocytosis	IMP PMID:10526320 Defective calmodulin-dependent rapid apical endocytosis in z...	KEEP AS NON CORE	Summary: endocytosis (GO:0006897) is retained as supported context for tomt but is not the primary/core function. Reason: This annotation predates the specific molecular role (Tmc trafficking) defined by Erickson et al. 2017. The 2000 study assayed mercury mutants in the context of calcium/calmodulin-dependent apical endocytosis, and the apparent endocytosis defect is now better explained as a downstream consequence of the mechanotransduction defect rather than a direct endocytic function of Tomt. Supporting Evidence: PMID:10526320 rapid apical endocytosis in zebrafish lateral line sensory hair cells is calcium and calmodulin dependent
GO:0035315 hair cell differentiation	IMP PMID:10526320 Defective calmodulin-dependent rapid apical endocytosis in z...	KEEP AS NON CORE	Summary: hair cell differentiation (GO:0035315) is retained as supported context for tomt but is not the primary/core function. Reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the central molecular role. Supporting Evidence: PMID:10526320 rapid apical endocytosis in zebrafish lateral line sensory hair cells is calcium and calmodulin dependent
GO:0048884 neuromast development	IMP PMID:9491988 Genetic analysis of vertebrate sensory hair cell mechanosens...	KEEP AS NON CORE	Summary: neuromast development (GO:0048884) is retained as supported context for tomt but is not the primary/core function. Reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the central molecular role. Supporting Evidence: PMID:9491988 orbiter, mercury, and gemini larvae have normal hair cell morphology and yet do not respond to acoustic-vibrational stimuli
GO:0050974 detection of mechanical stimulus involved in sensory perception	IMP PMID:9491988 Genetic analysis of vertebrate sensory hair cell mechanosens...	ACCEPT	Summary: detection of mechanical stimulus involved in sensory perception (GO:0050974) is supported for tomt. Reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene. Supporting Evidence: PMID:9491988 orbiter, mercury, and gemini larvae have normal hair cell morphology and yet do not respond to acoustic-vibrational stimuli file:DANRE/tomt/tomt-deep-research-falcon.md essential for hair-cell mechano-electrical transduction (MET)

Core Functions

Tomt is a Golgi/ER secretory-pathway chaperone/escort that physically interacts with TMC1 and is selectively required to traffic the Tmc1/Tmc2 MET channel subunits into hair-cell stereocilia, thereby enabling assembly of a functional mechanotransduction complex and mechanosensory hair-cell function. The required methyltransferase-like fold acts in this trafficking role independent of canonical catechol-O-methyltransferase catalysis; its physiological methyl-acceptor substrate is unknown.

Directly Involved In:

inner ear receptor cell stereocilium organization detection of mechanical stimulus involved in sensory perception

Cellular Locations:

endoplasmic reticulum Golgi apparatus basolateral plasma membrane

Supporting Evidence:

file:DANRE/tomt/tomt-uniprot.txt
Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia
PMID:28534737
Tomt is required for trafficking Tmc proteins to the hair bundle
file:DANRE/tomt/tomt-deep-research-falcon.md
functions primarily in the **secretory pathway (Golgi/ER)** to enable **trafficking and bundle targeting of Tmc1/Tmc2 (MET channel subunits)**

References

GO_REF:0000002

Gene Ontology annotation through association of InterPro records with GO terms

GO_REF:0000024

Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity

GO_REF:0000033

Annotation inferences using phylogenetic trees

GO_REF:0000044

Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

PMID:10526320

Defective calmodulin-dependent rapid apical endocytosis in zebrafish sensory hair cell mutants.

Hair-cell apical endocytosis depends on calcium/calmodulin and is defective in several auditory/vestibular mutants including mercury.

"rapid apical endocytosis in zebrafish lateral line sensory hair cells is calcium and calmodulin dependent"

PMID:28534737

Integration of Tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by Transmembrane O-methyltransferase (Tomt).

Tomt is required in zebrafish hair cells for Tmc1/2 trafficking and mechanotransduction.

"Tomt is required for trafficking Tmc proteins to the hair bundle"

PMID:9491988

Genetic analysis of vertebrate sensory hair cell mechanosensation: the zebrafish circler mutants.

The mercury mutant class has impaired acoustic-vibrational responses and reduced microphonics, supporting a mechanotransduction defect.

"orbiter, mercury, and gemini larvae have normal hair cell morphology and yet do not respond to acoustic-vibrational stimuli"

file:DANRE/tomt/tomt-uniprot.txt

UniProtKB entry A0A193KX02 for Danio rerio tomt

UniProt summarizes Tomt as a hair-cell mechanotransduction factor needed for TMC1/2 trafficking.

"Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia"

file:DANRE/tomt/tomt-deep-research-falcon.md

Falcon deep research for Danio rerio tomt (UniProt A0A193KX02)

Falcon deep research synthesizes the Erickson 2017 eLife study and the Jung & Muller 2023 review to conclude that zebrafish Tomt is a Golgi/ER secretory-pathway protein essential for hair-cell mechano-electrical transduction, where it selectively enables trafficking and bundle targeting of the Tmc1/Tmc2 MET channel subunits rather than acting as a bundle-resident structural channel component.

"functions primarily in the **secretory pathway (Golgi/ER)** to enable **trafficking and bundle targeting of Tmc1/Tmc2 (MET channel subunits)**"
Tomt is enriched in the Golgi and excluded from stereocilia bundles, Tmc1/Tmc2b fail to reach bundles in tomt mutants, and TOMT physically interacts with TMC1, supporting a chaperone/escort/trafficking-facilitator model in the secretory pathway.

"support a direct physical interaction between **TOMT and TMC1**, consistent with a model where TOMT acts as a chaperone/escort or trafficking facilitator in the secretory pathway"
The catalytic methyltransferase role is debated: although the methyltransferase-like region is required for rescue, canonical catechol-O-methyltransferase chemistry is not strictly required for MET, COMT cannot rescue tomt mutants, an active-site H183A mutant still rescues, and no physiological methyl-acceptor substrate is identified.

"key data suggest canonical catechol-O-methyltransferase chemistry is **not strictly required** for its MET role"

Suggested Experiments

Experiment: Define the Tomt-TMC1 interaction interface and test whether catalytically dead but binding-competent Tomt variants (e.g., H183A) fully restore Tmc bundle targeting and MET in tomt mutants.

Experiment: Perform unbiased biochemical screening (e.g., SAM-dependent methylation assays / proteomics) on Tomt-associated secretory-pathway clients to identify any endogenous methyl-acceptor substrate.

Deep Research

Falcon

(tomt-deep-research-falcon.md)

Research Report: Functional annotation of **tomt** (Danio rerio) / UniProt **A0A193KX02** Falcon Edison Scientific Literature 8 citations 2 artifacts 2026-05-31T16:56:17.374103

Edison artifact artifact-00 (text/markdown)

## Context ID: pqac-00000015 The requested figure panels have been extracted from the document: 1. **Tomt-GFP localization to the Golgi:** Figure 2C (image-003) (image/png)

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Research Report: Functional annotation of tomt (Danio rerio) / UniProt A0A193KX02

Executive summary

The zebrafish gene tomt (synonym mrc, historically linked to the mercury mutant) encodes a membrane-anchored, SAM-dependent methyltransferase–domain protein that is essential for hair-cell mechano-electrical transduction (MET). Experimental evidence indicates Tomt functions primarily in the secretory pathway (Golgi/ER) to enable trafficking and bundle targeting of Tmc1/Tmc2 (MET channel subunits), rather than acting as a stereocilia-resident structural component of the MET channel. Although Tomt is annotated as an O-methyltransferase homolog (EC 2.1.1.6), its physiological methyl-acceptor substrate remains unknown; key data suggest canonical catechol-O-methyltransferase chemistry is not strictly required for its MET role. (erickson2017integrationoftmc12 pages 1-2, erickson2017integrationoftmc12 pages 12-13, erickson2017integrationoftmc12 pages 13-16, jung2023mechanoelectricaltransductionrelatedgenetic pages 1-3)

1) Identity verification and definitions (critical disambiguation)

1.1 Gene/protein identity matches the UniProt target

Experimental zebrafish work explicitly describes tomt as the gene mutated in mercury alleles (also referred to as mrc) and as an ortholog of human LRTOMT/TOMT, the gene responsible for autosomal recessive nonsyndromic deafness DFNB63 (publication date: Jun 2017; URL https://doi.org/10.17863/cam.24577). (erickson2017integrationoftmc12 pages 1-2, erickson2017integrationoftmc12 pages 2-4)

1.2 Key concept definitions

Mechano-electrical transduction (MET): the process by which hair-cell stereocilia deflection opens a mechanosensitive ion channel, generating receptor current; in vertebrates the pore-forming channel subunits are widely attributed to TMC1/TMC2. (jung2023mechanoelectricaltransductionrelatedgenetic pages 1-3)
Tmc proteins (Tmc1/Tmc2): transmembrane channel-like proteins that are central subunits of the MET channel complex and must be properly trafficked into stereocilia bundles for MET to occur. (erickson2017integrationoftmc12 pages 1-2, jung2023mechanoelectricaltransductionrelatedgenetic pages 4-6)
Tomt/TOMT (transmembrane O-methyltransferase): a membrane-associated protein with a predicted SAM-dependent methyltransferase fold, genetically linked to deafness, that functions in the secretory pathway to enable TMC trafficking and MET competency. (erickson2017integrationoftmc12 pages 2-4, jung2023mechanoelectricaltransductionrelatedgenetic pages 4-6)

2) Current understanding of tomt function in zebrafish hair cells

2.1 Tomt is required for mechanotransduction (cell physiology)

In zebrafish, loss-of-function of tomt results in absence of MET function in hair cells, supported by multiple readouts: failure of MET-permeant FM dye uptake and electrophysiological absence of evoked MET currents. Importantly, other ionic currents characteristic of hair cells (e.g., K+ currents; inward Ca2+ currents used for cell identification) remain detectable, consistent with a specific MET defect rather than general hair-cell loss. (erickson2017integrationoftmc12 pages 16-18, erickson2017integrationoftmc12 pages 6-8)

2.2 Subcellular localization: Tomt is a secretory pathway protein

A functional Tomt-GFP fusion is reported to be enriched in the Golgi of zebrafish hair cells and excluded from the stereocilia bundle, placing Tomt in a compartment consistent with protein processing/trafficking rather than being a bundle-resident MET channel subunit. (erickson2017integrationoftmc12 pages 6-8, erickson2017integrationoftmc12 media 79e17c54)

2.3 Mechanistic role: selective trafficking/integration of Tmc1/Tmc2 into stereocilia

A central mechanistic finding is that Tmc1 and Tmc2b fail to localize to hair bundles in tomt-deficient hair cells; instead, tagged Tmc proteins remain in the cell body. In contrast, the paper reports that other MET-complex proteins can still localize to bundles, supporting a selective requirement for Tomt in Tmc trafficking/bundle targeting. (erickson2017integrationoftmc12 pages 13-16, erickson2017integrationoftmc12 media 1e07c0cf, erickson2017integrationoftmc12 media 85c8124b)

2.4 Rescue experiments: Tomt is necessary beyond development

Hair-cell expression of Tomt rescues MET function in tomt mutants, and acute induction experiments indicate Tomt can restore MET in mature mutant hair cells within ~4 hours, implying Tomt has an ongoing role in enabling/maintaining MET competency (e.g., via continued trafficking or turnover of MET components). (erickson2017integrationoftmc12 pages 12-13, erickson2017integrationoftmc12 pages 8-12)

2.5 Physical interaction with TMC1 supports a chaperone/trafficking model

Biochemical assays in heterologous cells support a direct physical interaction between TOMT and TMC1, consistent with a model where TOMT acts as a chaperone/escort or trafficking facilitator in the secretory pathway. (erickson2017integrationoftmc12 pages 13-16, erickson2017integrationoftmc12 pages 16-18)

3) Enzymatic activity, substrates, and the unresolved methyltransferase question

3.1 What is known

Tomt is described as a transmembrane O-methyltransferase homolog with a predicted SAM-dependent methyltransferase domain related to COMT-like enzymes, and truncation experiments indicate that the transmembrane domain and the enzymatic (methyltransferase-like) region are required for full rescue in the zebrafish functional assays. (erickson2017integrationoftmc12 pages 8-12, erickson2017integrationoftmc12 pages 1-2)

3.2 What is not yet established (critical limitation)

Despite domain annotations and the EC label, the available primary evidence does not identify a physiological Tomt substrate in hair cells, nor does it establish that catalytic methyl transfer (as opposed to a structural role of the methyltransferase fold) is the essential biochemical activity. Indeed, several results argue against a simple catecholamine-metabolism function: COMT cannot rescue tomt mutants, TOMT has only modest activity toward norepinephrine in vitro, and an active-site histidine mutation (H183A) can still support rescue in vivo. Collectively, these data support the interpretation that Tomt’s principal role in hair cells is Tmc trafficking/integration, and that its precise methyl-acceptor substrate specificity (if any) remains unknown. (erickson2017integrationoftmc12 pages 2-4, erickson2017integrationoftmc12 pages 12-13, erickson2017integrationoftmc12 pages 18-19)

4) Pathway context: Tomt in the MET assembly/trafficking pathway

The best-supported pathway placement for zebrafish Tomt is upstream of stereocilia-localized MET machinery: Tomt resides in the Golgi/secretory pathway, promotes trafficking of Tmc subunits to the bundle, and thereby enables assembly of a functional MET complex in stereocilia. This aligns with expert synthesis in a 2023 review, which frames TOMT as an ER/secretory-pathway protein required for transport of TMC1 into stereocilia and as a factor affecting MET function indirectly. (erickson2017integrationoftmc12 pages 18-19, jung2023mechanoelectricaltransductionrelatedgenetic pages 4-6)

5) Recent developments (2023–2024 prioritized)

5.1 2023 expert review perspective (authoritative synthesis)

A 2023 review of genetic forms of MET-related hearing loss discusses TOMT/LRTOMT mutations as the cause of DFNB63 and highlights evidence that TOMT is localized to the ER/secretory pathway and is required for TMC1 transport into stereocilia, supporting a trafficking/chaperone-like role rather than a stereocilia structural role. (Publication date: Apr 2023; URL https://doi.org/10.1016/j.cophys.2023.100632). (jung2023mechanoelectricaltransductionrelatedgenetic pages 1-3, jung2023mechanoelectricaltransductionrelatedgenetic pages 4-6)

5.2 2024 research and review context

Recent work on Tmc subunits in zebrafish vestibular function provides contemporary context for why Tomt-mediated trafficking of Tmcs is biologically consequential (Tmc subunit combinations tune vestibular frequency sensitivity). While this 2024 paper is not centered on Tomt, it exemplifies ongoing, current interest in Tmc-dependent MET properties in zebrafish and cites tomt mutants as a reference point for disrupted MET. (Publication date: Nov 2024; URL https://doi.org/10.1523/jneurosci.1298-23.2023). (jung2023mechanoelectricaltransductionrelatedgenetic pages 7-9)

6) Current applications and real-world implementations

6.1 Hearing-loss genetics and diagnostic interpretation

TOMT/LRTOMT is established in the hearing-loss genetics landscape as the DFNB63 gene, and zebrafish tomt mutants serve as a mechanistic disease model demonstrating that TOMT deficiency can cause deafness by preventing TMC channel subunits from reaching stereocilia. This provides a mechanistically grounded interpretive framework for TOMT variants identified in human genetic testing: pathogenic alleles are expected to impair MET by disrupting TMC trafficking rather than (or in addition to) altering catecholamine metabolism. (erickson2017integrationoftmc12 pages 1-2, jung2023mechanoelectricaltransductionrelatedgenetic pages 4-6)

6.2 Zebrafish models as functional annotation platforms

The tomt/mercury zebrafish line functions as an in vivo platform for:
- testing genetic rescue with orthologs (mouse TOMT rescues zebrafish),
- mapping secretory-pathway steps required for MET complex assembly,
- assessing stereocilia targeting determinants for Tmc proteins.
These are direct, real-world experimental implementations of tomt biology in sensory neuroscience research. (erickson2017integrationoftmc12 pages 12-13, erickson2017integrationoftmc12 pages 13-16)

7) Quantitative/statistical data points from retrieved studies

Time-to-functional restoration: heat-shock induction of Tomt-GFP restored MET function in previously silent mutant hair cells within approximately 4 hours. (erickson2017integrationoftmc12 pages 12-13, erickson2017integrationoftmc12 pages 8-12)
Imaging-based trafficking phenotype: Tmc1-GFP and Tmc2b-GFP are present in wild-type bundles but absent from mutant bundles (qualitative but direct phenotype), documented in extracted figure panels. (erickson2017integrationoftmc12 media 1e07c0cf, erickson2017integrationoftmc12 media 85c8124b)

8) Expert analysis and open questions

8.1 Consensus model supported by current evidence

The strongest experimentally supported model is that Tomt is a Golgi/ER-associated trafficking factor that enables incorporation of Tmc subunits into stereocilia, thereby allowing MET. This model is supported by localization data, selective Tmc mislocalization, rescue experiments, and TOMT–TMC1 interaction data, and it is echoed by authoritative review literature. (erickson2017integrationoftmc12 pages 13-16, erickson2017integrationoftmc12 pages 18-19, jung2023mechanoelectricaltransductionrelatedgenetic pages 4-6)

8.2 Key unresolved questions

Physiological methyl-acceptor substrate: No definitive endogenous substrate for Tomt in hair cells is identified in the retrieved evidence; whether Tomt performs methyl transfer on a protein/lipid/small molecule in the secretory pathway remains unknown. (erickson2017integrationoftmc12 pages 18-19)
Catalysis vs. scaffold: Active-site perturbation (H183A) not abolishing rescue suggests Tomt’s methyltransferase fold may serve a binding/chaperone function, or that catalysis involves non-canonical residues/substrates; resolving this requires direct biochemical identification of Tomt-dependent methylation events. (erickson2017integrationoftmc12 pages 12-13, erickson2017integrationoftmc12 pages 18-19)

Evidence summary table

Claim/Observation	Biological level (molecular/cellular/organism)	Evidence type (genetics, imaging, electrophysiology, biochemistry, review)	Key details (include quantitative where available)	Source (authors, year)	DOI/URL	Citation ID
Zebrafish tomt is the gene disrupted in the classic mercury/mrc mutant and is orthologous to human LRTOMT/TOMT (DFNB63)	Molecular/organism	Genetics	mercury alleles are nonsense mutations predicted to truncate Tomt before or within the putative O-methyltransferase domain; links zebrafish locus to human deafness gene ortholog	Erickson et al., 2017	https://doi.org/10.17863/cam.24577	(erickson2017integrationoftmc12 pages 1-2, erickson2017integrationoftmc12 pages 2-4)
Tomt is essential for hair-cell mechanotransduction; tomt mutants have auditory/vestibular dysfunction	Cellular/organism	Genetics, electrophysiology	tomt-deficient hair cells lack mechanotransduction (MET); mutants show auditory and vestibular phenotypes consistent with loss of sensory hair-cell function	Erickson et al., 2017	https://doi.org/10.17863/cam.24577	(erickson2017integrationoftmc12 pages 1-2, erickson2017integrationoftmc12 pages 6-8)
Tomt localizes to the secretory pathway rather than the hair bundle	Cellular	Imaging	GFP-tagged Tomt is enriched in the Golgi and excluded from stereociliary bundles; partial co-localization shown with medial Golgi marker Mgat1a_1–110-mKate2	Erickson et al., 2017	https://doi.org/10.17863/cam.24577	(erickson2017integrationoftmc12 pages 1-2, erickson2017integrationoftmc12 pages 12-13, erickson2017integrationoftmc12 pages 6-8, erickson2017integrationoftmc12 media 79e17c54)
Loss of Tomt selectively disrupts Tmc trafficking to the hair bundle	Cellular	Imaging, genetics	In tomt/mercury mutants, Tmc1-GFP and Tmc2b-GFP are absent from bundles and remain in the cell body, while other MET-complex proteins can still localize to bundles	Erickson et al., 2017	https://doi.org/10.17863/cam.24577	(erickson2017integrationoftmc12 pages 1-2, erickson2017integrationoftmc12 pages 2-4, erickson2017integrationoftmc12 pages 13-16, erickson2017integrationoftmc12 media 1e07c0cf, erickson2017integrationoftmc12 media 85c8124b)
Tomt acts cell-autonomously and can restore Tmc localization/MET when re-expressed	Cellular	Genetics, imaging, functional rescue	Mosaic Tomt expression restores Tmc2b-GFP bundle localization; hair-cell-specific Tomt-GFP rescues FM dye uptake and MET activity in mutants	Erickson et al., 2017	https://doi.org/10.17863/cam.24577	(erickson2017integrationoftmc12 pages 8-12, erickson2017integrationoftmc12 pages 13-16)
Tomt is required not only during development but also in mature hair cells	Cellular	Genetics, functional rescue	Heat-shock induction of Tomt-GFP restored previously silent mutant hair cells within ~4 h, indicating an ongoing role in maintaining/assembling MET function	Erickson et al., 2017	https://doi.org/10.17863/cam.24577	(erickson2017integrationoftmc12 pages 12-13, erickson2017integrationoftmc12 pages 8-12)
Tomt-deficient hair cells lack MET currents despite otherwise recognizable hair-cell ionic properties	Cellular	Electrophysiology	mercury/tomt mutant hair cells show no detectable evoked MET currents and loss of FM 1–43/FM 4–64 uptake, but retain normal K+ currents and intact inward Ca2+ current used to verify cell identity	Erickson et al., 2017	https://doi.org/10.17863/cam.24577	(erickson2017integrationoftmc12 pages 6-8, erickson2017integrationoftmc12 pages 16-18)
Mouse TOMT can substitute for zebrafish Tomt, but COMT cannot	Molecular/cellular	Genetics, rescue	Mouse TOMT-GFP restores mechanotransduction/FM dye uptake in mercury mutants, whereas zebrafish Comta-GFP does not rescue, arguing against a simple catecholamine-metabolism explanation	Erickson et al., 2017	https://doi.org/10.17863/cam.24577	(erickson2017integrationoftmc12 pages 2-4, erickson2017integrationoftmc12 pages 12-13, erickson2017integrationoftmc12 pages 18-19)
TOMT physically interacts with TMC1	Molecular	Biochemistry	HEK293 co-immunoprecipitation supports direct TOMT–TMC1 interaction; supports a trafficking/chaperone-like role in the secretory pathway	Erickson et al., 2017	https://doi.org/10.17863/cam.24577	(erickson2017integrationoftmc12 pages 1-2, erickson2017integrationoftmc12 pages 13-16, erickson2017integrationoftmc12 pages 16-18)
The putative catalytic histidine is not strictly required for Tomt-mediated rescue	Molecular/cellular	Mutagenesis, functional rescue, biochemistry	H183A in TOMT enhanced TOMT–TMC1 interaction in co-IP and did not abolish rescue in zebrafish assays; suggests canonical COMT-like active-site chemistry is not essential for hair-cell function	Erickson et al., 2017	https://doi.org/10.17863/cam.24577	(erickson2017integrationoftmc12 pages 12-13, erickson2017integrationoftmc12 pages 16-18, erickson2017integrationoftmc12 pages 18-19)
The enzymatic domain is functionally important, but the physiological substrate remains unknown	Molecular	Structure-function, biochemistry	Predicted SAM-dependent methyltransferase domain is required for rescue in truncation tests, yet no in vivo substrate is identified; only modest in vitro catechol O-methyltransferase activity toward norepinephrine reported, so true substrate specificity remains unresolved	Erickson et al., 2017	https://doi.org/10.17863/cam.24577	(erickson2017integrationoftmc12 pages 2-4, erickson2017integrationoftmc12 pages 8-12, erickson2017integrationoftmc12 pages 18-19, erickson2017integrationoftmc12 pages 1-2)
Recent expert reviews frame TOMT primarily as a TMC trafficking factor in MET biology	Molecular/cellular	Review	2023 review states TOMT/LRTOMT mutations cause DFNB63, places TOMT in ER/secretory-pathway trafficking of TMC1 into stereocilia, and treats TOMT as affecting MET indirectly rather than as a pore-forming channel component	Jung & Müller, 2023	https://doi.org/10.1016/j.cophys.2023.100632	(jung2023mechanoelectricaltransductionrelatedgenetic pages 1-3, jung2023mechanoelectricaltransductionrelatedgenetic pages 4-6, jung2023mechanoelectricaltransductionrelatedgenetic pages 7-9)

Table: This table compiles the core evidence linking zebrafish tomt/Tomt to hair-cell mechanotransduction, emphasizing gene identity, localization, Tmc trafficking, rescue experiments, and the unresolved question of catalytic methyltransferase activity.

Key figure evidence (visual)

Tomt-GFP Golgi co-localization panel supporting secretory-pathway localization. (erickson2017integrationoftmc12 media 79e17c54)
Tmc1/2-GFP bundle exclusion in tomt mutants supporting the trafficking defect mechanism. (erickson2017integrationoftmc12 media 1e07c0cf, erickson2017integrationoftmc12 media 85c8124b)

Bibliography (retrieved sources; publication dates and URLs)

Erickson T, Morgan CP, Olt J, et al. Integration of tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by Transmembrane O-methyltransferase (Tomt). eLife (posted/available Jun 2017). https://doi.org/10.17863/cam.24577 (erickson2017integrationoftmc12 pages 1-2)
Jung J, Müller U. Mechanoelectrical transduction-related genetic forms of hearing loss. Current Opinion in Physiology. Apr 2023. https://doi.org/10.1016/j.cophys.2023.100632 (jung2023mechanoelectricaltransductionrelatedgenetic pages 1-3)
Sun P, Smith E, Nicolson T. Transmembrane Channel-Like (Tmc) Subunits Contribute to Frequency Sensitivity in the Zebrafish Utricle. J Neurosci. Nov 2024. https://doi.org/10.1523/jneurosci.1298-23.2023 (jung2023mechanoelectricaltransductionrelatedgenetic pages 7-9)

Limitations of this report

Within the accessible corpus for this run, I did not retrieve 2023–2024 primary human cohort papers reporting TOMT variant frequencies, penetrance estimates, or large-scale genotype–phenotype statistics for DFNB63; therefore, real-world quantitative epidemiology for TOMT-related hearing loss is not comprehensively covered here. The mechanistic and functional annotation for zebrafish Tomt is strongly supported by primary experimental evidence and recent authoritative synthesis. (jung2023mechanoelectricaltransductionrelatedgenetic pages 4-6, erickson2017integrationoftmc12 pages 18-19)

References

(erickson2017integrationoftmc12 pages 1-2): Timothy Erickson, Clive P Morgan, Jennifer Olt, Katherine Hardy, Elisabeth Busch-Nentwich, Reo Maeda, Rachel Clemens, Jocelyn F Krey, Alex Nechiporuk, Peter G Barr-Gillespie, Walter Marcotti, and Teresa Nicolson. Integration of tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by transmembrane o-methyltransferase (tomt). JournalArticle, Jun 2017. URL: https://doi.org/10.17863/cam.24577, doi:10.17863/cam.24577. This article has 69 citations.
(erickson2017integrationoftmc12 pages 12-13): Timothy Erickson, Clive P Morgan, Jennifer Olt, Katherine Hardy, Elisabeth Busch-Nentwich, Reo Maeda, Rachel Clemens, Jocelyn F Krey, Alex Nechiporuk, Peter G Barr-Gillespie, Walter Marcotti, and Teresa Nicolson. Integration of tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by transmembrane o-methyltransferase (tomt). JournalArticle, Jun 2017. URL: https://doi.org/10.17863/cam.24577, doi:10.17863/cam.24577. This article has 69 citations.
(erickson2017integrationoftmc12 pages 13-16): Timothy Erickson, Clive P Morgan, Jennifer Olt, Katherine Hardy, Elisabeth Busch-Nentwich, Reo Maeda, Rachel Clemens, Jocelyn F Krey, Alex Nechiporuk, Peter G Barr-Gillespie, Walter Marcotti, and Teresa Nicolson. Integration of tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by transmembrane o-methyltransferase (tomt). JournalArticle, Jun 2017. URL: https://doi.org/10.17863/cam.24577, doi:10.17863/cam.24577. This article has 69 citations.
(jung2023mechanoelectricaltransductionrelatedgenetic pages 1-3): Jinsei Jung and Ulrich Müller. Mechanoelectrical transduction-related genetic forms of hearing loss. Current Opinion in Physiology, 32:100632, Apr 2023. URL: https://doi.org/10.1016/j.cophys.2023.100632, doi:10.1016/j.cophys.2023.100632. This article has 13 citations and is from a peer-reviewed journal.
(erickson2017integrationoftmc12 pages 2-4): Timothy Erickson, Clive P Morgan, Jennifer Olt, Katherine Hardy, Elisabeth Busch-Nentwich, Reo Maeda, Rachel Clemens, Jocelyn F Krey, Alex Nechiporuk, Peter G Barr-Gillespie, Walter Marcotti, and Teresa Nicolson. Integration of tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by transmembrane o-methyltransferase (tomt). JournalArticle, Jun 2017. URL: https://doi.org/10.17863/cam.24577, doi:10.17863/cam.24577. This article has 69 citations.
(jung2023mechanoelectricaltransductionrelatedgenetic pages 4-6): Jinsei Jung and Ulrich Müller. Mechanoelectrical transduction-related genetic forms of hearing loss. Current Opinion in Physiology, 32:100632, Apr 2023. URL: https://doi.org/10.1016/j.cophys.2023.100632, doi:10.1016/j.cophys.2023.100632. This article has 13 citations and is from a peer-reviewed journal.
(erickson2017integrationoftmc12 pages 16-18): Timothy Erickson, Clive P Morgan, Jennifer Olt, Katherine Hardy, Elisabeth Busch-Nentwich, Reo Maeda, Rachel Clemens, Jocelyn F Krey, Alex Nechiporuk, Peter G Barr-Gillespie, Walter Marcotti, and Teresa Nicolson. Integration of tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by transmembrane o-methyltransferase (tomt). JournalArticle, Jun 2017. URL: https://doi.org/10.17863/cam.24577, doi:10.17863/cam.24577. This article has 69 citations.
(erickson2017integrationoftmc12 pages 6-8): Timothy Erickson, Clive P Morgan, Jennifer Olt, Katherine Hardy, Elisabeth Busch-Nentwich, Reo Maeda, Rachel Clemens, Jocelyn F Krey, Alex Nechiporuk, Peter G Barr-Gillespie, Walter Marcotti, and Teresa Nicolson. Integration of tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by transmembrane o-methyltransferase (tomt). JournalArticle, Jun 2017. URL: https://doi.org/10.17863/cam.24577, doi:10.17863/cam.24577. This article has 69 citations.
(erickson2017integrationoftmc12 media 79e17c54): Timothy Erickson, Clive P Morgan, Jennifer Olt, Katherine Hardy, Elisabeth Busch-Nentwich, Reo Maeda, Rachel Clemens, Jocelyn F Krey, Alex Nechiporuk, Peter G Barr-Gillespie, Walter Marcotti, and Teresa Nicolson. Integration of tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by transmembrane o-methyltransferase (tomt). JournalArticle, Jun 2017. URL: https://doi.org/10.17863/cam.24577, doi:10.17863/cam.24577. This article has 69 citations.
(erickson2017integrationoftmc12 media 1e07c0cf): Timothy Erickson, Clive P Morgan, Jennifer Olt, Katherine Hardy, Elisabeth Busch-Nentwich, Reo Maeda, Rachel Clemens, Jocelyn F Krey, Alex Nechiporuk, Peter G Barr-Gillespie, Walter Marcotti, and Teresa Nicolson. Integration of tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by transmembrane o-methyltransferase (tomt). JournalArticle, Jun 2017. URL: https://doi.org/10.17863/cam.24577, doi:10.17863/cam.24577. This article has 69 citations.
(erickson2017integrationoftmc12 media 85c8124b): Timothy Erickson, Clive P Morgan, Jennifer Olt, Katherine Hardy, Elisabeth Busch-Nentwich, Reo Maeda, Rachel Clemens, Jocelyn F Krey, Alex Nechiporuk, Peter G Barr-Gillespie, Walter Marcotti, and Teresa Nicolson. Integration of tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by transmembrane o-methyltransferase (tomt). JournalArticle, Jun 2017. URL: https://doi.org/10.17863/cam.24577, doi:10.17863/cam.24577. This article has 69 citations.
(erickson2017integrationoftmc12 pages 8-12): Timothy Erickson, Clive P Morgan, Jennifer Olt, Katherine Hardy, Elisabeth Busch-Nentwich, Reo Maeda, Rachel Clemens, Jocelyn F Krey, Alex Nechiporuk, Peter G Barr-Gillespie, Walter Marcotti, and Teresa Nicolson. Integration of tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by transmembrane o-methyltransferase (tomt). JournalArticle, Jun 2017. URL: https://doi.org/10.17863/cam.24577, doi:10.17863/cam.24577. This article has 69 citations.
(erickson2017integrationoftmc12 pages 18-19): Timothy Erickson, Clive P Morgan, Jennifer Olt, Katherine Hardy, Elisabeth Busch-Nentwich, Reo Maeda, Rachel Clemens, Jocelyn F Krey, Alex Nechiporuk, Peter G Barr-Gillespie, Walter Marcotti, and Teresa Nicolson. Integration of tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by transmembrane o-methyltransferase (tomt). JournalArticle, Jun 2017. URL: https://doi.org/10.17863/cam.24577, doi:10.17863/cam.24577. This article has 69 citations.
(jung2023mechanoelectricaltransductionrelatedgenetic pages 7-9): Jinsei Jung and Ulrich Müller. Mechanoelectrical transduction-related genetic forms of hearing loss. Current Opinion in Physiology, 32:100632, Apr 2023. URL: https://doi.org/10.1016/j.cophys.2023.100632, doi:10.1016/j.cophys.2023.100632. This article has 13 citations and is from a peer-reviewed journal.

Artifacts

Edison artifact artifact-00

Citations

jung2023mechanoelectricaltransductionrelatedgenetic pages 1-3
jung2023mechanoelectricaltransductionrelatedgenetic pages 7-9
jung2023mechanoelectricaltransductionrelatedgenetic pages 4-6
https://doi.org/10.17863/cam.24577
https://doi.org/10.1016/j.cophys.2023.100632
https://doi.org/10.1523/jneurosci.1298-23.2023
https://doi.org/10.17863/cam.24577,
https://doi.org/10.1016/j.cophys.2023.100632,

📚 Additional Documentation

Notes

(tomt-notes.md)

tomt (Danio rerio) review notes

Batch 05 curation notes

Core interpretation: tomt encodes transmembrane O-methyltransferase (TOMT/mercury), an ER/Golgi/basolateral membrane protein required in zebrafish hair cells for TMC1/2 trafficking into stereocilia and mechanotransduction-complex assembly. Its catechol O-methyltransferase-like activity is retained as by-similarity biochemical context, but the core zebrafish role is hair-cell mechanotransduction machinery organization independent of methyltransferase activity.
Key UniProt support: Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia.
Existing GOA annotations were reviewed against this core role; broad, inferred, or downstream phenotype annotations were kept as non-core unless they overstate the direct function.

📄 View Raw YAML

id: A0A193KX02
gene_symbol: tomt
product_type: PROTEIN
status: INITIALIZED
taxon:
  id: NCBITaxon:7955
  label: Danio rerio
description: tomt encodes transmembrane O-methyltransferase (TOMT/mercury), an ER/Golgi/basolateral membrane protein required
  in zebrafish hair cells for TMC1/2 trafficking into stereocilia and mechanotransduction-complex assembly. Its catechol O-methyltransferase-like
  activity is retained as by-similarity biochemical context, but the core zebrafish role is hair-cell mechanotransduction
  machinery organization independent of methyltransferase catalysis. Falcon deep research and UniProt converge on a Golgi/ER
  secretory-pathway chaperone/escort that physically interacts with TMC1 and is selectively required for Tmc1/Tmc2 delivery
  to the hair bundle; the physiological methyl-acceptor substrate is unknown and a simple catecholamine-metabolism role is
  argued against.
existing_annotations:
- term:
    id: GO:0032502
    label: developmental process
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: developmental process (GO:0032502) likely overstates or misdirects the direct function of tomt.
    action: MARK_AS_OVER_ANNOTATED
    reason: |-
      The evidence is better explained by the gene core function (selective Tmc trafficking for mechanotransduction) than
      by a general developmental role. Falcon shows the tomt loss-of-function phenotype is a specific MET defect, with other
      hair-cell properties retained, rather than a broad developmental failure.
    supported_by:
    - reference_id: file:DANRE/tomt/tomt-uniprot.txt
      supporting_text: Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia
    - reference_id: PMID:28534737
      supporting_text: Tomt is required for trafficking Tmc proteins to the hair bundle
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: consistent with a specific MET defect rather than general hair-cell loss
- term:
    id: GO:0016206
    label: catechol O-methyltransferase activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: catechol O-methyltransferase activity (GO:0016206) is retained as supported context for tomt but is not the primary/core
      function.
    action: KEEP_AS_NON_CORE
    reason: |-
      The SAM-dependent methyltransferase fold is genuinely present and the methyltransferase-like region is required for rescue,
      so this molecular function is plausible by-similarity context. However, falcon shows the physiological role in MET is
      independent of canonical catechol-O-methyltransferase catalysis and the endogenous methyl-acceptor substrate is unknown,
      so this term is non-core.
    supported_by:
    - reference_id: file:DANRE/tomt/tomt-uniprot.txt
      supporting_text: Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia
    - reference_id: PMID:28534737
      supporting_text: His183 in the putative active site of TOMT
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: |-
        its physiological methyl-acceptor substrate remains unknown
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: the **transmembrane domain and the enzymatic (methyltransferase-like) region are required** for full rescue
- term:
    id: GO:0042417
    label: dopamine metabolic process
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: dopamine metabolic process (GO:0042417) is likely an over-annotation of tomt based on family/sequence similarity,
      not the physiological function.
    action: MARK_AS_OVER_ANNOTATED
    reason: |-
      This is a phylogenetic/by-similarity transfer from COMT-like enzymes. Falcon shows several results argue against a simple
      catecholamine-metabolism function for Tomt (COMT cannot rescue tomt mutants, only modest in vitro activity, active-site
      H183A still rescues), and no dopamine-metabolism role is demonstrated in zebrafish hair cells.
    supported_by:
    - reference_id: file:DANRE/tomt/tomt-uniprot.txt
      supporting_text: Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia
    - reference_id: PMID:28534737
      supporting_text: Mechanotransduction in mercury mutants can be rescued by transgenic expression of either zebrafish Tomt
        or mouse TOMT, but not with the closely related Comt enzyme
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: several results argue against a simple catecholamine-metabolism function
- term:
    id: GO:0042424
    label: catecholamine catabolic process
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: catecholamine catabolic process (GO:0042424) is likely an over-annotation of tomt based on family/sequence similarity,
      not the physiological function.
    action: MARK_AS_OVER_ANNOTATED
    reason: |-
      This is a by-similarity transfer from COMT-like enzymes. Falcon shows the data argue against a simple catecholamine-metabolism
      function, including that COMT cannot rescue tomt mutants and an active-site histidine mutation still supports rescue; no
      catecholamine catabolism role is demonstrated for zebrafish Tomt.
    supported_by:
    - reference_id: file:DANRE/tomt/tomt-uniprot.txt
      supporting_text: Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia
    - reference_id: PMID:28534737
      supporting_text: Mechanotransduction in mercury mutants can be rescued by transgenic expression of either zebrafish Tomt
        or mouse TOMT, but not with the closely related Comt enzyme
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: COMT cannot rescue tomt mutants, TOMT has only modest activity toward norepinephrine in vitro, and an active-site
        histidine mutation (H183A) can still support rescue in vivo
- term:
    id: GO:0005783
    label: endoplasmic reticulum
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  review:
    summary: endoplasmic reticulum (GO:0005783) is supported for tomt.
    action: ACCEPT
    reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene.
    supported_by:
    - reference_id: file:DANRE/tomt/tomt-uniprot.txt
      supporting_text: Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia
    - reference_id: PMID:28534737
      supporting_text: Tomt-GFP may be present at lower levels in the endoplasmic reticulum and the basolateral membrane in
        addition to the Golgi apparatus
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: TOMT is localized to the ER/secretory pathway and is required for **TMC1 transport into stereocilia**
- term:
    id: GO:0005794
    label: Golgi apparatus
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  review:
    summary: Golgi apparatus (GO:0005794) is supported for tomt.
    action: ACCEPT
    reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene.
    supported_by:
    - reference_id: file:DANRE/tomt/tomt-uniprot.txt
      supporting_text: Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia
    - reference_id: PMID:28534737
      supporting_text: Tomt-GFP and Mgat1a_1-110-mKate2 are partially co-localized in hair cells
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: GFP-tagged Tomt is enriched in the Golgi and excluded from stereociliary bundles
- term:
    id: GO:0008171
    label: O-methyltransferase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  review:
    summary: O-methyltransferase activity (GO:0008171) is retained as supported context for tomt but is not the primary/core
      function.
    action: KEEP_AS_NON_CORE
    reason: |-
      The predicted SAM-dependent methyltransferase domain is present and required for rescue, so this molecular function is
      plausible by-similarity context. Falcon shows the physiological MET role does not depend on canonical methyltransferase
      catalysis and no endogenous methyl-acceptor substrate is identified, so this term is non-core.
    supported_by:
    - reference_id: file:DANRE/tomt/tomt-uniprot.txt
      supporting_text: Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia
    - reference_id: PMID:28534737
      supporting_text: His183 in the putative active site of TOMT
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: the **transmembrane domain and the enzymatic (methyltransferase-like) region are required** for full rescue
- term:
    id: GO:0016206
    label: catechol O-methyltransferase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: catechol O-methyltransferase activity (GO:0016206) is retained as supported context for tomt but is not the primary/core
      function.
    action: KEEP_AS_NON_CORE
    reason: |-
      The SAM-dependent methyltransferase fold is genuinely present and the methyltransferase-like region is required for rescue,
      so this molecular function is plausible by-similarity context. However, falcon shows the physiological role in MET is
      independent of canonical catechol-O-methyltransferase catalysis and the endogenous methyl-acceptor substrate is unknown,
      so this term is non-core.
    supported_by:
    - reference_id: file:DANRE/tomt/tomt-uniprot.txt
      supporting_text: Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia
    - reference_id: PMID:28534737
      supporting_text: His183 in the putative active site of TOMT
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: |-
        its physiological methyl-acceptor substrate remains unknown
- term:
    id: GO:0016323
    label: basolateral plasma membrane
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  review:
    summary: basolateral plasma membrane (GO:0016323) is supported for tomt.
    action: ACCEPT
    reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene.
    supported_by:
    - reference_id: file:DANRE/tomt/tomt-uniprot.txt
      supporting_text: Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia
    - reference_id: PMID:28534737
      supporting_text: Tomt-GFP may be present at lower levels in the endoplasmic reticulum and the basolateral membrane in
        addition to the Golgi apparatus
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: functions primarily in the **secretory pathway (Golgi/ER)** to enable **trafficking and bundle targeting
        of Tmc1/Tmc2 (MET channel subunits)**
- term:
    id: GO:0016206
    label: catechol O-methyltransferase activity
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  review:
    summary: catechol O-methyltransferase activity (GO:0016206) is retained as supported context for tomt but is not the primary/core
      function.
    action: KEEP_AS_NON_CORE
    reason: |-
      The SAM-dependent methyltransferase fold is genuinely present and the methyltransferase-like region is required for rescue,
      so this molecular function is plausible by-similarity context. However, falcon shows the physiological role in MET is
      independent of canonical catechol-O-methyltransferase catalysis and the endogenous methyl-acceptor substrate is unknown,
      so this term is non-core.
    supported_by:
    - reference_id: file:DANRE/tomt/tomt-uniprot.txt
      supporting_text: Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia
    - reference_id: PMID:28534737
      supporting_text: His183 in the putative active site of TOMT
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: |-
        its physiological methyl-acceptor substrate remains unknown
- term:
    id: GO:0005783
    label: endoplasmic reticulum
  evidence_type: IDA
  original_reference_id: PMID:28534737
  review:
    summary: endoplasmic reticulum (GO:0005783) is supported for tomt.
    action: ACCEPT
    reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene.
    supported_by:
    - reference_id: PMID:28534737
      supporting_text: Tomt-GFP may be present at lower levels in the endoplasmic reticulum and the basolateral membrane in
        addition to the Golgi apparatus
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: TOMT is localized to the ER/secretory pathway and is required for **TMC1 transport into stereocilia**
- term:
    id: GO:0005794
    label: Golgi apparatus
  evidence_type: IDA
  original_reference_id: PMID:28534737
  review:
    summary: Golgi apparatus (GO:0005794) is supported for tomt.
    action: ACCEPT
    reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene.
    supported_by:
    - reference_id: PMID:28534737
      supporting_text: Tomt-GFP and Mgat1a_1-110-mKate2 are partially co-localized in hair cells
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: A functional Tomt-GFP fusion is reported to be **enriched in the Golgi** of zebrafish hair cells and excluded
        from the stereocilia bundle
- term:
    id: GO:0016323
    label: basolateral plasma membrane
  evidence_type: IDA
  original_reference_id: PMID:28534737
  review:
    summary: basolateral plasma membrane (GO:0016323) is supported for tomt.
    action: ACCEPT
    reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene.
    supported_by:
    - reference_id: PMID:28534737
      supporting_text: Tomt-GFP may be present at lower levels in the endoplasmic reticulum and the basolateral membrane in
        addition to the Golgi apparatus
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: functions primarily in the **secretory pathway (Golgi/ER)** to enable **trafficking and bundle targeting
        of Tmc1/Tmc2 (MET channel subunits)**
- term:
    id: GO:0031223
    label: auditory behavior
  evidence_type: IMP
  original_reference_id: PMID:28534737
  review:
    summary: auditory behavior (GO:0031223) is a supported organism-level phenotype for tomt but is not a direct core gene
      function.
    action: KEEP_AS_NON_CORE
    reason: Tomt directly supports hair-cell mechanotransduction-complex assembly and TMC trafficking; auditory behavior is
      a downstream systems-level phenotype.
    supported_by:
    - reference_id: PMID:28534737
      supporting_text: non-transgenic mercury mutants exhibited a startle response to 2% of stimuli, confirming that Tomt-deficient
        zebrafish are deaf
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: mutants show auditory and vestibular phenotypes consistent with loss of sensory hair-cell function
- term:
    id: GO:0042424
    label: catecholamine catabolic process
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  review:
    summary: catecholamine catabolic process (GO:0042424) is likely an over-annotation of tomt based on family/sequence similarity,
      not the physiological function.
    action: MARK_AS_OVER_ANNOTATED
    reason: |-
      This is a by-similarity transfer from COMT-like enzymes. Falcon shows the data argue against a simple catecholamine-metabolism
      function, including that COMT cannot rescue tomt mutants and an active-site histidine mutation still supports rescue; no
      catecholamine catabolism role is demonstrated for zebrafish Tomt.
    supported_by:
    - reference_id: file:DANRE/tomt/tomt-uniprot.txt
      supporting_text: Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia
    - reference_id: PMID:28534737
      supporting_text: Mechanotransduction in mercury mutants can be rescued by transgenic expression of either zebrafish Tomt
        or mouse TOMT, but not with the closely related Comt enzyme
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: COMT cannot rescue tomt mutants, TOMT has only modest activity toward norepinephrine in vitro, and an active-site
        histidine mutation (H183A) can still support rescue in vivo
- term:
    id: GO:0060122
    label: inner ear receptor cell stereocilium organization
  evidence_type: IMP
  original_reference_id: PMID:28534737
  review:
    summary: inner ear receptor cell stereocilium organization (GO:0060122) is supported for tomt.
    action: ACCEPT
    reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene.
    supported_by:
    - reference_id: PMID:28534737
      supporting_text: GFP-tagged Tmc1 and Tmc2b fail to localize to the hair bundle in mercury mutants
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: Tmc1-GFP** and **Tmc2b-GFP** are absent from bundles and remain in the cell body
- term:
    id: GO:0006897
    label: endocytosis
  evidence_type: IMP
  original_reference_id: PMID:10526320
  review:
    summary: endocytosis (GO:0006897) is retained as supported context for tomt but is not the primary/core function.
    action: KEEP_AS_NON_CORE
    reason: |-
      This annotation predates the specific molecular role (Tmc trafficking) defined by Erickson et al. 2017. The 2000 study
      assayed mercury mutants in the context of calcium/calmodulin-dependent apical endocytosis, and the apparent endocytosis
      defect is now better explained as a downstream consequence of the mechanotransduction defect rather than a direct
      endocytic function of Tomt.
    supported_by:
    - reference_id: PMID:10526320
      supporting_text: rapid apical endocytosis in zebrafish lateral line sensory hair cells is calcium and calmodulin dependent
- term:
    id: GO:0035315
    label: hair cell differentiation
  evidence_type: IMP
  original_reference_id: PMID:10526320
  review:
    summary: hair cell differentiation (GO:0035315) is retained as supported context for tomt but is not the primary/core
      function.
    action: KEEP_AS_NON_CORE
    reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the
      central molecular role.
    supported_by:
    - reference_id: PMID:10526320
      supporting_text: rapid apical endocytosis in zebrafish lateral line sensory hair cells is calcium and calmodulin dependent
- term:
    id: GO:0048884
    label: neuromast development
  evidence_type: IMP
  original_reference_id: PMID:9491988
  review:
    summary: neuromast development (GO:0048884) is retained as supported context for tomt but is not the primary/core function.
    action: KEEP_AS_NON_CORE
    reason: This annotation is broad, inferred, or reflects downstream developmental/physiological context rather than the
      central molecular role.
    supported_by:
    - reference_id: PMID:9491988
      supporting_text: orbiter, mercury, and gemini larvae have normal hair cell morphology and yet do not respond to acoustic-vibrational
        stimuli
- term:
    id: GO:0050974
    label: detection of mechanical stimulus involved in sensory perception
  evidence_type: IMP
  original_reference_id: PMID:9491988
  review:
    summary: detection of mechanical stimulus involved in sensory perception (GO:0050974) is supported for tomt.
    action: ACCEPT
    reason: This annotation matches the synthesized core function or a directly supported core location/process for this gene.
    supported_by:
    - reference_id: PMID:9491988
      supporting_text: orbiter, mercury, and gemini larvae have normal hair cell morphology and yet do not respond to acoustic-vibrational
        stimuli
    - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
      supporting_text: essential for hair-cell mechano-electrical transduction (MET)
references:
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO terms
  findings: []
- id: GO_REF:0000024
  title: Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence
    similarity
  findings: []
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative
    changes to GO terms applied by UniProt
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:10526320
  title: Defective calmodulin-dependent rapid apical endocytosis in zebrafish sensory hair cell mutants.
  findings:
  - statement: Hair-cell apical endocytosis depends on calcium/calmodulin and is defective in several auditory/vestibular
      mutants including mercury.
    supporting_text: rapid apical endocytosis in zebrafish lateral line sensory hair cells is calcium and calmodulin dependent
- id: PMID:28534737
  title: Integration of Tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by Transmembrane
    O-methyltransferase (Tomt).
  findings:
  - statement: Tomt is required in zebrafish hair cells for Tmc1/2 trafficking and mechanotransduction.
    supporting_text: Tomt is required for trafficking Tmc proteins to the hair bundle
- id: PMID:9491988
  title: 'Genetic analysis of vertebrate sensory hair cell mechanosensation: the zebrafish circler mutants.'
  findings:
  - statement: The mercury mutant class has impaired acoustic-vibrational responses and reduced microphonics, supporting a
      mechanotransduction defect.
    supporting_text: orbiter, mercury, and gemini larvae have normal hair cell morphology and yet do not respond to acoustic-vibrational
      stimuli
- id: file:DANRE/tomt/tomt-uniprot.txt
  title: UniProtKB entry A0A193KX02 for Danio rerio tomt
  findings:
  - statement: UniProt summarizes Tomt as a hair-cell mechanotransduction factor needed for TMC1/2 trafficking.
    supporting_text: Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia
- id: file:DANRE/tomt/tomt-deep-research-falcon.md
  title: Falcon deep research for Danio rerio tomt (UniProt A0A193KX02)
  findings:
  - statement: |-
      Falcon deep research synthesizes the Erickson 2017 eLife study and the Jung & Muller 2023 review to conclude that
      zebrafish Tomt is a Golgi/ER secretory-pathway protein essential for hair-cell mechano-electrical transduction, where
      it selectively enables trafficking and bundle targeting of the Tmc1/Tmc2 MET channel subunits rather than acting as a
      bundle-resident structural channel component.
    supporting_text: functions primarily in the **secretory pathway (Golgi/ER)** to enable **trafficking and bundle targeting
      of Tmc1/Tmc2 (MET channel subunits)**
    reference_section_type: OTHER
  - statement: |-
      Tomt is enriched in the Golgi and excluded from stereocilia bundles, Tmc1/Tmc2b fail to reach bundles in tomt mutants,
      and TOMT physically interacts with TMC1, supporting a chaperone/escort/trafficking-facilitator model in the secretory
      pathway.
    supporting_text: support a direct physical interaction between **TOMT and TMC1**, consistent with a model where TOMT acts
      as a chaperone/escort or trafficking facilitator in the secretory pathway
    reference_section_type: OTHER
  - statement: |-
      The catalytic methyltransferase role is debated: although the methyltransferase-like region is required for rescue,
      canonical catechol-O-methyltransferase chemistry is not strictly required for MET, COMT cannot rescue tomt mutants,
      an active-site H183A mutant still rescues, and no physiological methyl-acceptor substrate is identified.
    supporting_text: key data suggest canonical catechol-O-methyltransferase chemistry is **not strictly required** for its
      MET role
    reference_section_type: OTHER
core_functions:
- description: Tomt is a Golgi/ER secretory-pathway chaperone/escort that physically interacts with TMC1 and is selectively
    required to traffic the Tmc1/Tmc2 MET channel subunits into hair-cell stereocilia, thereby enabling assembly of a functional
    mechanotransduction complex and mechanosensory hair-cell function. The required methyltransferase-like fold acts in this
    trafficking role independent of canonical catechol-O-methyltransferase catalysis; its physiological methyl-acceptor substrate
    is unknown.
  supported_by:
  - reference_id: file:DANRE/tomt/tomt-uniprot.txt
    supporting_text: Required for transportation of TMC1 and TMC2 proteins into the mechanically sensitive stereocilia
  - reference_id: PMID:28534737
    supporting_text: Tomt is required for trafficking Tmc proteins to the hair bundle
  - reference_id: file:DANRE/tomt/tomt-deep-research-falcon.md
    supporting_text: functions primarily in the **secretory pathway (Golgi/ER)** to enable **trafficking and bundle targeting
      of Tmc1/Tmc2 (MET channel subunits)**
  directly_involved_in:
  - id: GO:0060122
    label: inner ear receptor cell stereocilium organization
  - id: GO:0050974
    label: detection of mechanical stimulus involved in sensory perception
  locations:
  - id: GO:0005783
    label: endoplasmic reticulum
  - id: GO:0005794
    label: Golgi apparatus
  - id: GO:0016323
    label: basolateral plasma membrane
suggested_questions:
- question: What is the physiological methyl-acceptor substrate of Tomt in hair cells, if any, and is methyl transfer required
    for Tmc trafficking?
- question: Does Tomt act as a dedicated TMC chaperone in the secretory pathway, or does it more broadly assist folding/trafficking
    of other MET-complex membrane proteins?
suggested_experiments:
- description: Define the Tomt-TMC1 interaction interface and test whether catalytically dead but binding-competent Tomt variants
    (e.g., H183A) fully restore Tmc bundle targeting and MET in tomt mutants.
- description: Perform unbiased biochemical screening (e.g., SAM-dependent methylation assays / proteomics) on Tomt-associated
    secretory-pathway clients to identify any endogenous methyl-acceptor substrate.

tomt

Gene Description

Existing Annotations Review

Core Functions

References

Suggested Questions for Experts

Suggested Experiments

Deep Research

Falcon

Research Report: Functional annotation of tomt (Danio rerio) / UniProt A0A193KX02

Executive summary

1) Identity verification and definitions (critical disambiguation)

1.1 Gene/protein identity matches the UniProt target

1.2 Key concept definitions

2) Current understanding of tomt function in zebrafish hair cells

2.1 Tomt is required for mechanotransduction (cell physiology)

2.2 Subcellular localization: Tomt is a secretory pathway protein

2.3 Mechanistic role: selective trafficking/integration of Tmc1/Tmc2 into stereocilia

2.4 Rescue experiments: Tomt is necessary beyond development

2.5 Physical interaction with TMC1 supports a chaperone/trafficking model

3) Enzymatic activity, substrates, and the unresolved methyltransferase question

3.1 What is known

3.2 What is not yet established (critical limitation)

4) Pathway context: Tomt in the MET assembly/trafficking pathway

5) Recent developments (2023–2024 prioritized)

5.1 2023 expert review perspective (authoritative synthesis)

5.2 2024 research and review context

6) Current applications and real-world implementations

6.1 Hearing-loss genetics and diagnostic interpretation

6.2 Zebrafish models as functional annotation platforms

7) Quantitative/statistical data points from retrieved studies

8) Expert analysis and open questions

8.1 Consensus model supported by current evidence

8.2 Key unresolved questions

Evidence summary table

Key figure evidence (visual)

Bibliography (retrieved sources; publication dates and URLs)

Limitations of this report

Artifacts

Citations

📚 Additional Documentation

Notes

tomt (Danio rerio) review notes

Batch 05 curation notes

📄 View Raw YAML