Affinage

TMIE

Transmembrane inner ear expressed protein · UniProt Q8NEW7

Length
156 aa
Mass
17.2 kDa
Annotated
2026-06-10
22 papers in source corpus 11 papers cited in narrative 11 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

TMIE is an essential, integral subunit of the mechanotransduction (MET) channel complex in inner ear hair cells, where it physically and functionally couples the tip link to the ion channel that converts mechanical force into electrical signal (PMID:25467981, PMID:19934034). It assembles into a ternary complex with the tip-link protein PCDH15 and its partner TMHS/LHFPL5, and loss of TMIE or point mutations disrupting these interactions abolish transducer currents (PMID:25467981). TMIE directly binds the pore-forming subunits TMC1/2 and is required for their targeting and stabilization at the stereocilia hair bundle; in zebrafish tmie mutants TMC1/TMC2b fail to localize to the bundle, and the extracellular and transmembrane regions of TMIE mediate this targeting (PMID:30726219). Beyond targeting, TMIE robustly modulates TMC1/2 gating and single-channel conductance, with TMC1+TMIE and TMC2+TMIE reconstituting 18 pS and 24 pS channels resembling the native transducer, a stimulatory activity that depends on TMIE palmitoylation at C76/C77 (PMID:39999170). A C-terminal cytoplasmic domain bearing charged residues binds phospholipids including PIP2; deafness-linked mutations in this domain disrupt phospholipid binding and alter unitary conductance and ion selectivity, and PIP2 interaction with TMIE mediates slow adaptation of the channel independent of myosin motors [PMID:32343945, PMID:bio_10.1101_2025.04.01.646713]. Loss-of-function Tmie mutations in mice cause stereocilia defects, loss of tip links, and profound failure to develop auditory function, and transgenic re-expression rescues hearing dose-dependently (PMID:12140191, PMID:18586001).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 2002 Medium

    Established TMIE as a gene required for hair-cell stereocilia integrity and auditory function, defining it as a candidate mechanotransduction component before any molecular role was known.

    Evidence Positional cloning and characterization of two independent loss-of-function Tmie alleles in mice with ABR and electron microscopy readouts

    PMID:12140191

    Open questions at the time
    • Did not define the molecular activity of TMIE
    • Could not distinguish a developmental role from a direct transduction role
  2. 2009 High

    Showed TMIE is required for transduction channel function and tip-link integrity, linking the gene directly to the mechanotransduction apparatus rather than only stereocilia morphology.

    Evidence FM1-43 dye uptake, microphonic recordings, and ultrastructural analysis of tip links in tmie zebrafish frameshift mutants

    PMID:19934034

    Open questions at the time
    • Did not identify the molecular partners of TMIE
    • Could not separate channel function loss from secondary loss of tip links
  3. 2013 Medium

    Confirmed in mammals that TMIE is required for transducer channel permeability before hair-cell degeneration, ruling out the phenotype being a mere consequence of cell death.

    Evidence Gentamicin-Texas Red and FM1-43 channel-permeant dye uptake in P3 cir/cir vs control mouse hair cells

    PMID:23582420

    Open questions at the time
    • Single-method permeability assay without electrophysiology
    • Did not address mechanism of channel involvement
  4. 2014 High

    Placed TMIE within a defined molecular complex, showing it forms a ternary complex with PCDH15 and TMHS/LHFPL5 that couples the tip link to the channel.

    Evidence Reciprocal Co-IP and pulldown, electrophysiology in Tmie-null and point-mutant mice, and PCDH15 splicing analysis

    PMID:25467981

    Open questions at the time
    • Did not establish a direct link between TMIE and the pore-forming channel subunits
    • Mechanism of force coupling not resolved
  5. 2019 High

    Resolved TMIE's role as a chaperone/targeting factor for the TMC channel subunits, explaining how loss of TMIE abolishes transduction.

    Evidence Live imaging of GFP-tagged Tmc1/Tmc2b localization in tmie zebrafish nulls plus systematic domain-deletion rescue with functional readout

    PMID:30726219

    Open questions at the time
    • Did not demonstrate direct TMIE–TMC binding biochemically
    • Did not address whether TMIE also modulates channel gating
  6. 2020 High

    Defined TMIE as a channel subunit that directly binds TMC1/2 and harbors a C-terminal phospholipid-sensing domain regulating channel biophysics.

    Evidence Co-IP of TMIE–TMC1/2, site-directed mutagenesis, whole-cell and single-channel electrophysiology, and PIP2 depletion/lipid-binding assays in hair cells

    PMID:32343945

    Open questions at the time
    • Did not reconstitute the channel outside hair cells
    • Mechanism linking PIP2 binding to adaptation not established
  7. 2025 High

    Demonstrated by heterologous reconstitution that TMIE stimulates TMC1/2 gating via palmitoylation at C76/C77, separating TMIE's gating-modulation function from its trafficking role.

    Evidence Heterologous expression of Fyn-tagged TMC1/2 ± TMIE with single-channel patch clamp and C76C77A palmitoylation-site mutagenesis

    PMID:39999170

    Open questions at the time
    • Did not reconstitute the full native complex including PCDH15/LHFPL5
    • Role of palmitoylation in trafficking vs gating not fully dissected
  8. 2025 Medium

    Linked TMIE's PIP2 interaction to a specific physiological process, slow adaptation, acting independently of myosin motors.

    Evidence Electrophysiology of slow adaptation with pharmacological myosin inhibition and exogenous PIP2 rescue in cochlear/vestibular hair cells and Tmie mutants (preprint)

    PMID:bio_10.1101_2025.04.01.646713

    Open questions at the time
    • Preprint not yet peer-reviewed
    • Structural basis of PIP2 sensing not resolved
    • Quantitative coupling between PIP2 binding and adaptation kinetics undefined

Open questions

Synthesis pass · forward-looking unresolved questions
  • The atomic structure of TMIE within the assembled MET complex and the mechanism by which mechanical force at the tip link is transmitted through TMIE to gate the TMC pore remain unresolved.
  • No high-resolution structure of the TMIE-containing MET complex
  • Force-transmission pathway from PCDH15 to TMC via TMIE not mechanistically defined

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0008289 lipid binding 2 GO:0060089 molecular transducer activity 2 GO:0098772 molecular function regulator activity 2
Localization
GO:0005856 cytoskeleton 2 GO:0005886 plasma membrane 2
Pathway
R-HSA-112316 Neuronal System 2 R-HSA-9709957 Sensory Perception 2
Complex memberships
mechanotransduction (MET) channel complex

Evidence

Reading pass · 11 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2014 TMIE forms a ternary complex with the tip-link component PCDH15 and its binding partner TMHS/LHFPL5 in cochlear hair cells. Alternative splicing of the PCDH15 cytoplasmic domain regulates formation of this ternary complex. Homozygous Tmie-null mutation abolishes transducer currents, and subtle Tmie mutations that disrupt interactions between TMIE and tip links impair transduction, establishing TMIE as an essential component of the mechanotransduction machinery that functionally couples the tip link to the transduction channel. Co-immunoprecipitation, pulldown assays, electrophysiology in Tmie-null and point-mutant mice, alternative splicing analysis Neuron High 25467981
2020 TMIE binds TMC1/2 and is required for TMC1/2 to form functional mechanotransduction channels; a TMIE mutation that perturbs TMC1/2 binding abolishes mechanotransduction. N-terminal TMIE deletions alter channel responses to mechanical force. The C-terminal cytoplasmic domain of TMIE contains charged residues that mediate binding to phospholipids including PIP2; deafness-linked C-terminal point mutations disrupt phospholipid binding, sensitize the channel to PIP2 depletion, and alter unitary conductance and ion selectivity, defining TMIE as a channel subunit with a phospholipid-sensing domain. Co-immunoprecipitation (TMIE–TMC1/2 binding), site-directed mutagenesis, whole-cell and single-channel electrophysiology in hair cells, PIP2 depletion assays, N-terminal deletion constructs Neuron High 32343945
2019 In zebrafish tmie mutants, GFP-tagged Tmc1 and Tmc2b fail to target to the hair bundle, while Tmie overexpression strongly enhances Tmc1/Tmc2b targeting to stereocilia. Systematic deletion/replacement of Tmie peptide segments showed that the extracellular region and transmembrane domain are required for both mechanosensitivity and Tmc2b-GFP bundle expression, indicating TMIE's role is to target and stabilize Tmc channel subunits at the site of mechanotransduction. Fluorescence imaging of GFP-tagged TMC subunits in tmie zebrafish mutants, domain-deletion and chimeric Tmie rescue constructs, functional electrophysiology PLoS genetics High 30726219
2025 Mouse TMC1/2 with a Fyn lipidation tag can reach the cell surface and form mechanosensitive channels in heterologous cells without TMIE, but TMIE robustly stimulates TMC1/2 channel activity by modulating their gating. Palmitoylation sites C76/C77 on TMIE are essential for this stimulation; mutating these sites eliminates TMIE's ability to enhance TMC1/2 gating. TMC1+TMIE and TMC2+TMIE form 18 pS and 24 pS single channels, respectively, with biophysical properties similar to the native mechanotransduction channel. Heterologous expression of Fyn-tagged TMC1/2 ± TMIE in non-hair cells, single-channel patch-clamp electrophysiology, site-directed mutagenesis of TMIE palmitoylation sites (C76C77A) Proceedings of the National Academy of Sciences of the United States of America High 39999170
2009 In tmie zebrafish mutants (frameshift mutation), hair cells fail to incorporate FM1-43 and other fluorophores that traverse transduction channels, lack microphonic potentials, have short/disordered hair bundles, and stereocilia lack tip links and insertional plaques, establishing that TMIE is required for mechanotransduction channel function and tip-link integrity in hair cells. Positional cloning, FM1-43 dye uptake assay, microphonic potential recordings, electron/confocal microscopy of hair bundles in tmie zebrafish mutants Proceedings of the National Academy of Sciences of the United States of America High 19934034
2013 Hair cells of tmie-null (cir/cir) mice at postnatal day 3 (before hair-cell degeneration) fail to take up gentamicin, gentamicin-Texas Red conjugate, or FM1-43, compounds that enter hair cells through the mechanotransducer channel, demonstrating that TMIE is required for mechanotransducer channel activity. FM1-43 and gentamicin-Texas Red uptake assays in cir/cir vs control hair cells at P3 Comparative medicine Medium 23582420
2002 Loss-of-function mutations in the mouse Tmie gene (40-kb deletion in spinner allele; nonsense mutation in a second allele) cause postnatal defects in cochlear hair cell stereocilia and profound failure to develop auditory function, establishing that Tmie is required for stereocilia integrity and mechanotransduction in mammalian hair cells. Positional cloning, genomic deletion characterization, auditory brainstem response, scanning/transmission electron microscopy of stereocilia in Tmie-null mice Human molecular genetics Medium 12140191
2018 Ectopic expression of wild-type tmie transgene in cir/cir (Tmie-null) mice rescues hearing and vestibular behavior in a dose-dependent manner, with recovery correlating with cochlear transgene expression level, confirming that the tmie protein itself is the functional unit responsible for hearing. Transgenic rescue experiment in cir/cir mice; ABR and behavioral phenotype assessment correlated with cochlear transgene expression levels by Western blot Biochemical and biophysical research communications Medium 18586001
2008 Tmie protein is expressed and localized to the stereocilia bundles of cochlear hair cells in the rat, with prominent expression in early postnatal stages, implicating it in stereocilia maturation; expression detected by immunostaining with a Tmie-specific antibody identifying a 17 kDa band on Western blot. Immunohistochemistry with anti-Tmie antibody, Western blot, RT-PCR in rat cochlea Histochemistry and cell biology Low 18327602
2011 In a stable cell line expressing Myc-tagged Tmie, the protein localizes predominantly to the cellular membrane and to a lesser extent the cytoplasm, consistent with its predicted transmembrane domain architecture. Stable transfection of Myc-tagged Tmie, immunostaining with anti-Myc and anti-Tmie antibodies, Western blot Laboratory animal research Low 22232643
2025 Slow adaptation of the mechanotransduction channel in mammalian cochlear and vestibular hair cells depends on PIP2 interactions with Tmie, independent of myosin motors. Slow adaptation is independent of myosin VIIa (upper tip-link motor), and exogenous PIP2 rescues slow adaptation when myosin motors are pharmacologically inhibited, supporting a model in which PIP2 binding by Tmie mediates slow adaptation at the lower end of the tip link. Electrophysiological recording of slow adaptation in cochlear and vestibular hair cells; pharmacological myosin inhibition; exogenous PIP2 application; analysis in Tmie mutant cells bioRxivpreprint Medium bio_10.1101_2025.04.01.646713

Source papers

Stage 0 corpus · 22 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2014 TMIE is an essential component of the mechanotransduction machinery of cochlear hair cells. Neuron 181 25467981
2002 Mutations in a novel gene, TMIE, are associated with hearing loss linked to the DFNB6 locus. American journal of human genetics 109 12145746
2020 TMIE Defines Pore and Gating Properties of the Mechanotransduction Channel of Mammalian Cochlear Hair Cells. Neuron 102 32343945
2002 Mutation of the novel gene Tmie results in sensory cell defects in the inner ear of spinner, a mouse model of human hearing loss DFNB6. Human molecular genetics 92 12140191
2009 The transmembrane inner ear (Tmie) protein is essential for normal hearing and balance in the zebrafish. Proceedings of the National Academy of Sciences of the United States of America 74 19934034
2014 Non-syndromic hearing impairment in India: high allelic heterogeneity among mutations in TMPRSS3, TMC1, USHIC, CDH23 and TMIE. PloS one 49 24416283
2019 Subunits of the mechano-electrical transduction channel, Tmc1/2b, require Tmie to localize in zebrafish sensory hair cells. PLoS genetics 47 30726219
2008 The transmembrane inner ear (tmie) gene contributes to vestibular and lateral line development and function in the zebrafish (Danio rerio). Developmental dynamics : an official publication of the American Association of Anatomists 25 18330929
2006 The circling mouse (C57BL/6J-cir) has a 40-kilobase genomic deletion that includes the transmembrane inner ear (tmie) gene. Comparative medicine 21 17219777
2005 Novel sequence variants in the TMIE gene in families with autosomal recessive nonsyndromic hearing impairment. Journal of molecular medicine (Berlin, Germany) 19 16389551
2009 A founder TMIE mutation is a frequent cause of hearing loss in southeastern Anatolia. Clinical genetics 14 19438934
2021 How Transmembrane Inner Ear (TMIE) plays role in the auditory system: A mystery to us. Journal of cellular and molecular medicine 13 33987950
2008 Expression and localization of Tmie in adult rat cochlea. Histochemistry and cell biology 13 18327602
2010 Spatiotemporal expression of tmie in the inner ear of rats during postnatal development. Comparative medicine 12 20819378
2013 tmie Is required for gentamicin uptake by the hair cells of mice. Comparative medicine 10 23582420
2025 Ectopic mouse TMC1 and TMC2 alone form mechanosensitive channels that are potently modulated by TMIE. Proceedings of the National Academy of Sciences of the United States of America 8 39999170
2010 Identification of novel variants in the TMIE gene of patients with nonsyndromic hearing loss. International journal of pediatric otorhinolaryngology 8 20206386
2008 Ectopic expression of tmie transgene induces various recovery levels of behavior and hearing ability in the circling mouse. Biochemical and biophysical research communications 6 18586001
2022 Analysis of TMIE gene mutations including the first large deletion of exon 1 with autosomal recessive non-syndromic deafness. BMC medical genomics 5 35710363
2014 A precisely defined role for the tip link-associated protein TMIE in the mechanoelectrical transduction channel complex of inner ear hair cells. Neuron 3 25475183
2012 Expression of deafness protein Tmie in postnatal developmental stages of C57BL/6J mice. Laboratory animal research 3 22787490
2011 Subcellular localization of the transmembrane inner ear (Tmie) protein in a stable Tmie-expressing cell line. Laboratory animal research 1 22232643

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