Affinage

TMX1

Thioredoxin-related transmembrane protein 1 · UniProt Q9H3N1

Length
280 aa
Mass
31.8 kDa
Annotated
2026-06-10
29 papers in source corpus 12 papers cited in narrative 12 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

TMX1 is a transmembrane ER oxidoreductase whose N-terminal thioredoxin-like domain (CPAC active site) faces the ER lumen and possesses PDI-like disulfide-isomerase activity in vitro (PMID:14871470). Palmitoylation of cysteines adjacent to its transmembrane domain targets a pool of TMX1 to the mitochondria-associated membrane (MAM), where both this lipid modification and the CPAC redox motif are required for TMX1 to sustain ER-to-mitochondria Ca²⁺ flux, mitochondrial Ca²⁺ uptake, and bioenergetic coupling, thereby promoting apoptotic progression (PMID:22045338, PMID:27502484). Within the ER, TMX1 partners with the lectin calnexin and acts as a topology-specific redox catalyst, preferentially engaging the disulfide bonds of membrane-anchored client proteins while ignoring identical soluble ectodomains, a selectivity that operates both in productive folding and in the reductive dislocation of misfolded substrates during ERAD (PMID:26246604, PMID:29932915). Its catalytic redox state is dynamic, becoming reversibly oxidized upon ER protein overload ahead of canonical stress markers and held reduced at baseline through glutathione (PMID:29123984). Beyond the ER, TMX1 functions at the cell surface: it acts as an oxidase that re-oxidizes the αIIbβ3 integrin and inhibits ERp46, counterbalancing ERp46-driven platelet activation and thereby negatively regulating platelet aggregation and thrombosis (PMID:30425049, PMID:39247212). TMX1 also protects against TNF-α-driven inflammatory liver injury (PMID:22924822), and its abundance is post-translationally controlled by a CCT2/TRIM28-catalyzed SUMO2 modification that blocks ubiquitin-mediated degradation (PMID:41168408).

Mechanistic history

Synthesis pass · year-by-year structured walk · 11 steps
  1. 2004 Medium

    Establishing that TMX1 is a thioredoxin-family enzyme rather than an inert membrane protein answered whether it carries genuine redox catalytic activity and where it resides.

    Evidence Subcellular fractionation, membrane topology mapping, and in vitro refolding of scrambled RNase by recombinant TMX

    PMID:14871470

    Open questions at the time
    • No mutagenesis confirming the CPAC residues drive activity
    • No identification of physiological substrates
    • In vitro activity not linked to a cellular process
  2. 2011 High

    Identifying palmitoylation as the targeting signal explained how a single ER oxidoreductase is partitioned to the MAM, defining the structural basis for its later contact-site functions.

    Evidence Palmitoylation-site mutagenesis and chemical inhibition with fractionation/immunofluorescence, paralleled in calnexin

    PMID:22045338

    Open questions at the time
    • Did not establish what TMX1 does at the MAM
    • Palmitoyltransferase responsible not identified
  3. 2012 Medium

    A knockout mouse showed TMX1 has a protective physiological role in vivo, linking its redox function to suppression of inflammatory tissue damage.

    Evidence TMX1-knockout mice in LPS/GalN and thioacetamide liver injury models with TNF-α neutralization epistasis

    PMID:22924822

    Open questions at the time
    • Molecular substrate mediating protection unknown
    • Connection to ER/MAM redox catalysis not established
    • p53 activation correlative
  4. 2015 High

    Defining TMX1 as a topology-specific catalyst acting on membrane-anchored clients in complex with calnexin answered how the enzyme achieves substrate selectivity in living cells.

    Evidence Reciprocal Co-IP of TMX1–calnexin and substrate assays comparing membrane-anchored versus soluble ectodomains

    PMID:26246604

    Open questions at the time
    • Structural basis of topology discrimination unresolved
    • Full client repertoire not defined
  5. 2016 High

    Functional dissection at the MAM established TMX1 as a thiol-based regulator of ER-mitochondria Ca²⁺ transfer and bioenergetics, tying its redox motif and palmitoylation to organelle communication and apoptosis.

    Evidence TMX1 KO/KD with CPAC and palmitoylation mutants, Ca²⁺ imaging, mitochondrial ATP measurement, and contact-site quantification

    PMID:27502484

    Open questions at the time
    • Direct redox substrate at the MAM controlling Ca²⁺ flux not identified
    • Mechanism linking TMX1 redox state to contact-site formation unclear
  6. 2017 Medium

    Showing TMX1 oxidation precedes BiP induction positioned its redox state as an early sensor of ER protein load buffered by glutathione.

    Evidence Alkylation-based redox trapping with brefeldin A treatment/washout and glutathione depletion

    PMID:29123984

    Open questions at the time
    • No mutagenesis of the responsive cysteines
    • Downstream consequences of oxidation not defined
  7. 2018 Medium

    Extending topology-specific reduction into ERAD answered whether TMX1's selectivity principle operates in protein degradation as well as folding.

    Evidence ERAD substrate degradation assays comparing membrane-tethered versus soluble misfolded polypeptides under TMX1 knockdown

    PMID:29932915

    Open questions at the time
    • Single lab
    • Coupling between disulfide reduction and dislocation machinery not detailed
  8. 2018 High

    Identifying surface TMX1 as an oxidase of αIIbβ3 revealed an unexpected extracellular, anti-thrombotic role, the first inhibitory thiol isomerase regulator of platelets.

    Evidence TMX1 KO mouse, recombinant extracellular domain, anti-TMX1 antibody, β3 thiol labeling, aggregation/ATP-release assays, and FeCl3 thrombosis model

    PMID:30425049

    Open questions at the time
    • How an ER oxidoreductase reaches the platelet surface unclear
    • Full set of surface substrates not mapped
  9. 2024 Medium

    Defining TMX1's interplay with ERp46 explained how opposing thiol enzymes set platelet integrin activation thresholds.

    Evidence ERp46- and TMX1-deficient platelets, wild-type versus catalytically inactive TMX1 protein, thiol labeling, reductase assays, aggregation and clot retraction

    PMID:39247212

    Open questions at the time
    • Stoichiometry of TMX1/ERp46 regulation in vivo unknown
    • Single lab
  10. 2024 Medium

    A proximity-labeling screen placed TMX1 at the TCR, showing it engages the CD3δ CxxC motif to support receptor assembly and T cell signaling.

    Evidence APEX2 proximity labeling with CD8α bait, CRISPR TMX1 deletion, CD3ζ overexpression rescue, surface TCR and signaling readouts (preprint)

    PMID:39386445

    Open questions at the time
    • Not peer-reviewed and single lab
    • Direct redox chemistry on CD3δ not demonstrated
    • Generality across T cell subsets untested
  11. 2025 Medium

    Discovery of TMX1 binding FABP5 and a CCT2/TRIM28 SUMO2 axis revealed how TMX1 abundance is post-translationally controlled and links it to ferroptosis resistance and drug tolerance in cancer.

    Evidence Co-IP, ubiquitination/SUMOylation assays, KD/OE with rescue, ROS measurements, and xenograft models in HCC and NSCLC

    PMID:41168408 PMID:41482143

    Open questions at the time
    • Whether TMX1 redox activity is required for the FABP5 and ROS effects not separated from scaffolding
    • No structural validation of the interactions
    • Single lab each

Open questions

Synthesis pass · forward-looking unresolved questions
  • How TMX1 is trafficked among the ER lumen, MAM, and the cell surface, and which physiological substrates it acts on at each location, remains unresolved.
  • No unified model linking ER, MAM, and surface pools
  • Surface-targeting mechanism unknown
  • Comprehensive substrate map across compartments lacking

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0140096 catalytic activity, acting on a protein 5 GO:0016491 oxidoreductase activity 3 GO:0016853 isomerase activity 2
Localization
GO:0005783 endoplasmic reticulum 3 GO:0005739 mitochondrion 2 GO:0005886 plasma membrane 2
Pathway
R-HSA-392499 Metabolism of proteins 3 R-HSA-109582 Hemostasis 2 R-HSA-168256 Immune System 1 R-HSA-5357801 Programmed Cell Death 1
Complex memberships
TCR–CD3 complexTMX1–calnexin complex

Evidence

Reading pass · 12 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2004 TMX1 (TMX) is a transmembrane oxidoreductase localized to the ER membrane with its N-terminal thioredoxin-like domain (CPAC active site) facing the ER lumen; recombinant TMX showed PDI-like refolding activity on scrambled RNase in vitro. Subcellular fractionation, membrane topology analysis, in vitro refolding assay (scrambled RNase) Archives of biochemistry and biophysics Medium 14871470
2011 Palmitoylation of cysteine residue(s) adjacent to the transmembrane domain of TMX1 is required for its enrichment on the mitochondria-associated membrane (MAM); mutation of the palmitoylation site or chemical interference with palmitoylation disrupts MAM localization. Palmitoylation site mutagenesis, chemical inhibition of palmitoylation, subcellular fractionation/immunofluorescence The EMBO journal High 22045338
2015 TMX1 forms functional complexes with the ER lectin calnexin and preferentially acts on cysteine-containing, membrane-anchored client proteins during folding, while ignoring the same cysteine-containing ectodomains when not membrane-tethered; TMX1 is the first topology-specific client protein redox catalyst in living cells. Co-immunoprecipitation (TMX1–calnexin complex), substrate specificity assays comparing membrane-anchored vs. soluble ectodomains, KD/KO with defined folding phenotype Molecular biology of the cell High 26246604
2016 TMX1 regulates ER-to-mitochondria Ca²⁺ flux at the MAM; its thioredoxin (CPAC) motif and palmitoylation-dependent MAM targeting are both required for this function. Low TMX1 reduces ER-mitochondria contacts, decreases mitochondrial Ca²⁺ uptake, shifts bioenergetics away from mitochondria, and reduces apoptosis progression. TMX1 knockout/knockdown, CPAC active-site mutant, palmitoylation mutant; Ca²⁺ imaging, mitochondrial ATP measurements, ER-mitochondria contact site quantification The Journal of cell biology High 27502484
2017 TMX1 is reversibly oxidized in response to ER protein overload (brefeldin A-induced protein accumulation); oxidation precedes the classical ER stress marker BiP induction, and glutathione is involved in maintaining TMX1 in its reduced (basal) state. Redox state analysis (alkylation-based trapping), BFA treatment and washout, glutathione depletion experiments FEBS open bio Medium 29123984
2018 TMX1 acts as a topology-specific reductase in ERAD, preferentially reducing disulfide bonds of membrane-tethered misfolded polypeptides to facilitate their dislocation, while ignoring the same misfolded ectodomains when soluble. ERAD substrate degradation assays, membrane-anchored vs. soluble substrate comparisons, TMX1 knockdown with defined ERAD phenotype Biochemical and biophysical research communications Medium 29932915
2018 TMX1 is expressed on the platelet surface and acts as an oxidase toward the αIIbβ3 integrin; TMX1-deficient platelets have increased free thiols on the β3 subunit, and recombinant extracellular TMX1 inhibits platelet aggregation, ATP release, αIIbβ3 activation, and P-selectin expression, making it the first identified negative (inhibitory) extracellular thiol isomerase regulator of platelet function. TMX1 knockout mouse model, recombinant extracellular domain protein (rTMX1) addition, anti-TMX1 antibody, thiol-labeling of αIIbβ3, platelet aggregation and ATP release assays, FeCl3 mesenteric arterial injury thrombosis model Blood High 30425049
2012 TMX1-deficient mice are highly susceptible to LPS/d-galactosamine-induced inflammatory liver injury, with enhanced p53-signaling pathway activation in the liver; TNF-α neutralization suppressed the toxic phenotype, indicating TMX1 protects against oxidative inflammatory damage downstream of TNF-α signaling. TMX1 knockout mouse model, LPS/GalN and thioacetamide liver injury models, liver transcriptional profiling, TNF-α neutralization Antioxidants & redox signaling Medium 22924822
2024 TMX1 directly engages the CxxC motif of CD3δ (a TCR complex subunit); loss of TMX1 decreases surface TCR expression and destabilizes CD3ζ, impairing TCR assembly and T cell cytotoxicity as well as NFAT, NFκB, and AP1 signaling. Overexpression of CD3ζ rescues the phenotype, indicating TMX1 is required for TCR assembly but not for CD3ζ function per se. APEX2 proximity labeling screen (CD8α bait), CRISPR TMX1 deletion, CD3ζ overexpression rescue, surface TCR expression assays, T cell signaling readouts bioRxivpreprint Medium 39386445
2024 TMX1 oxidizes ERp46 (inhibiting its reductase activity) and also re-oxidizes the αIIbβ3 disulfides that ERp46 reduces, thereby counterbalancing ERp46-mediated platelet activation; TMX1 deficiency increases free thiols on ERp46 in platelets, an effect reversed by addition of wild-type but not catalytically inactive TMX1. ERp46- and TMX1-deficient platelets, wild-type vs. inactive TMX1 protein addition, thiol labeling, reductase activity assays, platelet aggregation and clot retraction assays Research and practice in thrombosis and haemostasis Medium 39247212
2025 TMX1 binds FABP5 and competitively blocks interaction between FABP5 and the E3 ubiquitin ligase NEDD4, preventing K48-linked ubiquitination and degradation of FABP5, thereby enhancing FABP5-mediated inhibition of ferroptosis in hepatocellular carcinoma cells. Co-immunoprecipitation (TMX1–FABP5 interaction), ubiquitination assays, TMX1 KD/OE with FABP5 KD rescue, in vivo xenograft model Cellular signalling Medium 41482143
2025 CCT2 recruits TRIM28 to catalyze SUMO2 modification of TMX1, which inhibits TMX1 ubiquitination and stabilizes the protein; this stabilized TMX1 promotes ROS clearance, conferring resistance to third-generation EGFR tyrosine kinase inhibitors in NSCLC. CRISPR/Cas9 genome-wide screen, TMT proteomics, SUMO2 modification assays, ubiquitination assays, TMX1 KD with ROS measurements, xenograft models Cell death and differentiation Medium 41168408

Source papers

Stage 0 corpus · 29 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2011 Palmitoylated TMX and calnexin target to the mitochondria-associated membrane. The EMBO journal 196 22045338
2016 TMX1 determines cancer cell metabolism as a thiol-based modulator of ER-mitochondria Ca2+ flux. The Journal of cell biology 129 27502484
2012 Biodegradation of the neonicotinoid insecticide thiamethoxam by the nitrogen-fixing and plant-growth-promoting rhizobacterium Ensifer adhaerens strain TMX-23. Applied microbiology and biotechnology 71 23274958
2020 Development of CDK2 and CDK5 Dual Degrader TMX-2172. Angewandte Chemie (International ed. in English) 63 32415712
2018 The transmembrane protein disulfide isomerase TMX1 negatively regulates platelet responses. Blood 41 30425049
2020 Thioredoxin-Related Transmembrane Proteins: TMX1 and Little Brothers TMX2, TMX3, TMX4 and TMX5. Cells 39 32878123
2004 TMX, a human transmembrane oxidoreductase of the thioredoxin family: the possible role in disulfide-linked protein folding in the endoplasmic reticulum. Archives of biochemistry and biophysics 38 14871470
2016 A phase 2 study of TMX-101, intravesical imiquimod, for the treatment of carcinoma in situ bladder cancer. Urologic oncology 34 28341495
2012 Results of a phase 1 dose escalation study of intravesical TMX-101 in patients with nonmuscle invasive bladder cancer. The Journal of urology 32 23206424
2022 Hyaluronic acid-coated chitosan nanoparticles as targeted-carrier of tamoxifen against MCF7 and TMX-resistant MCF7 cells. Journal of materials science. Materials in medicine 30 35157166
2015 Division of labor among oxidoreductases: TMX1 preferentially acts on transmembrane polypeptides. Molecular biology of the cell 24 26246604
2020 An endophytic bacterial strain, Enterobacter cloacae TMX-6, enhances the degradation of thiamethoxam in rice plants. Chemosphere 23 33139042
2002 Tamoxifen (TMX)/Fas induced growth inhibition of human cholangiocarcinoma (HCC) by gamma interferon (IFN-gamma). Annals of surgery 22 12035045
2021 Introducing Thioredoxin-Related Transmembrane Proteins: Emerging Roles of Human TMX and Clinical Implications. Antioxidants & redox signaling 16 34465218
2014 Pharmacokinetic, Pharmacodynamic, and Activity Evaluation of TMX-101 in a Multicenter Phase 1 Study in Patients With Papillary Non-Muscle-Invasive Bladder Cancer. Clinical genitourinary cancer 16 25660383
2012 The protective role of the transmembrane thioredoxin-related protein TMX in inflammatory liver injury. Antioxidants & redox signaling 14 22924822
2018 The reductase TMX1 contributes to ERAD by preferentially acting on membrane-associated folding-defective polypeptides. Biochemical and biophysical research communications 13 29932915
2017 Transmembrane thioredoxin-related protein TMX1 is reversibly oxidized in response to protein accumulation in the endoplasmic reticulum. FEBS open bio 12 29123984
2023 Selenium alleviates biological toxicity of thiamethoxam (TMX): Bioaccumulation of TMX, organ damage, and antioxidant response of red swamp crayfish (Procambarus clarkii). Journal of hazardous materials 10 37364439
2024 Melodinines J Induces Apoptosis in Temozolomide-Resistant Glioma Cells by Disrupting TMX1-Dependent Homeostasis of Endoplasmic Reticulum-Mitochondria-Associated Membrane Contacts. Phytotherapy research : PTR 8 39715722
2018 A placebo-controlled efficacy study of the intravesical immunomodulators TMX-101 and TMX-202 in an orthotopic bladder cancer rat model. World journal of urology 7 29767328
2011 Pharmacokinetics and toxicity of intravesical TMX-101: a preclinical study in pigs. BJU international 7 21314886
2021 Copper stimulates neonicotinoid insecticide thiacloprid degradation by Ensifer adhaerens TMX-23. Journal of applied microbiology 6 34075672
2024 Transmembrane thiol isomerase TMX1 counterbalances the effect of ERp46 to inhibit platelet activation and integrin αIIbβ3 function. Research and practice in thrombosis and haemostasis 3 39247212
2018 Pharmacokinetics and pharmacodynamics of intravesical and intravenous TMX-101 and TMX-202 in a F344 rat model. Urologic oncology 3 29500135
2017 Estradiol (E2)- and tamoxifen (Tmx)-bound ER-alpha (ERα) interact differentially with histone deacetylases 1 and 3 (HDACs 1 and 3). The Journal of steroid biochemistry and molecular biology 2 28847748
2024 TMX1, a disulfide oxidoreductase, is necessary for T cell function through regulation of CD3ζ. bioRxiv : the preprint server for biology 1 39386445
2025 CRISPR/Cas9 library screening uncovered CCT2 as a critical driver of acquired resistance to EGFR-targeted therapy by stabilizing TMX1 in non-small cell lung cancer. Cell death and differentiation 0 41168408
2025 TMX1 promotes the progression of hepatocellular carcinoma by inhibiting ferroptosis via stabilizing FABP5. Cellular signalling 0 41482143

Missed literature

Know a paper Affinage missed for TMX1? Flag it for the maintainers and the community.

No submissions yet.