{"gene":"TMEM33","run_date":"2026-06-10T10:51:55","timeline":{"discoveries":[{"year":2010,"finding":"Pom33 (yeast TMEM33 ortholog) is an integral transmembrane protein dynamically associated with nuclear pore complexes (NPCs) in budding yeast. Loss of Pom33 impairs NPC distribution and NPC density in the daughter nucleus, and Pom33 becomes essential for viability in the absence of the Nup84 complex or Ndc1 interaction network. Pom33 associates physically with the reticulon Rtn1.","method":"Yeast genetics (synthetic lethality, deletion mutants), co-immunoprecipitation, fluorescence microscopy of NPC distribution","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple genetic and cell biological methods in a focused study, independently foundational for the TMEM33 family","pmids":["20498018"],"is_preprint":false},{"year":2014,"finding":"Nuclear pore targeting of yeast Pom33 requires two redundant mechanisms: direct interaction of its C-terminal domain (CTD) with the karyopherin Kap123 (identified by Co-IP/MS and confirmed by in vitro binding assay), and membrane association via amphipathic α-helices in the CTD that preferentially bind highly curved lipid membranes (shown by circular dichroism and liposome co-flotation assays). Combined impairment of both lipid-binding and Kap123-binding abolishes NPC targeting.","method":"Co-immunoprecipitation/mass spectrometry, in vitro protein-protein binding, circular dichroism, liposome co-flotation, yeast mutant analysis","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — multiple orthogonal in vitro and in vivo methods establishing mechanism in a single rigorous study","pmids":["25413348"],"is_preprint":false},{"year":2014,"finding":"Fission yeast Tts1 (TMEM33 ortholog) localizes to high-curvature ER domains via an amphipathic helix in its C-terminus and functions in two distinct processes during closed mitosis: (1) promoting spindle pole body (SPB) insertion into the nuclear envelope (NE), dependent on conserved residues at the luminal interface of the third transmembrane region; and (2) modulating NPC distribution during mitotic NE expansion, dependent on the amphipathic helix.","method":"Fluorescence microscopy, domain mutagenesis, yeast deletion mutants, live-cell imaging","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — structure-function mutagenesis dissecting two distinct roles, multiple orthogonal methods","pmids":["25103238"],"is_preprint":false},{"year":2014,"finding":"Human TMEM33 was identified as a reticulon-binding protein by affinity chromatography. TMEM33 binds reticulon 4C, reticulon 1A, reticulon 2B, reticulon 3C, and the reticulon homology domain protein Arl6IP1. TMEM33 localizes to the ER membrane and nuclear envelope, co-localizes with reticulon 4C at ER sheets and partially at ER tubules, and exogenous TMEM33 expression suppresses reticulon 4C-induced ER tubulation.","method":"Affinity chromatography, co-immunoprecipitation, immunofluorescence microscopy, ER morphology assay","journal":"The Kobe journal of medical sciences","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — multiple binding partners confirmed, functional ER tubulation suppression assay, single lab","pmids":["25612671"],"is_preprint":false},{"year":2015,"finding":"TMEM33 is an ER stress-inducible transmembrane protein that localizes to the ER and physically binds PERK (an ER transmembrane kinase). Exogenous TMEM33 expression increases phosphorylation of eIF2α and IRE1α and elevates their downstream effectors ATF4-CHOP and XBP1-S, as well as apoptotic markers (cleaved caspase-7, cleaved PARP) and autophagosome marker LC3II.","method":"Immunoprecipitation, immunofluorescence, subcellular fractionation, immunoblotting, transient transfection","journal":"Breast cancer research and treatment","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — Co-IP identifies PERK binding, functional overexpression data with multiple readouts, single lab","pmids":["26268696"],"is_preprint":false},{"year":2019,"finding":"TMEM33 localizes to the ER in zebrafish endothelial cells and is required for cytosolic calcium oscillations in response to VEGF-A. Global or endothelial-specific knockdown of tmem33 impairs ERK phosphorylation, Notch signaling, tip cell filopodia formation, endothelial cell migration, and embryonic vascular development.","method":"Zebrafish genetic knockdown (morpholino/CRISPR), live calcium imaging, siRNA knockdown in human ECs, immunofluorescence, in vivo vascular development assays","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple organisms (zebrafish and human ECs), multiple orthogonal functional readouts, specific calcium imaging and signaling assays","pmids":["30760708"],"is_preprint":false},{"year":2019,"finding":"TMEM33 interacts with the ion channel polycystin-2 (PC2) at the ER membrane, enhancing PC2 channel opening across the physiological calcium range (demonstrated in ER liposomes fused to planar bilayers). Consequently, TMEM33 reduces intracellular calcium content in a PC2-dependent manner, impairs lysosomal calcium refilling, causes cathepsin translocation, inhibits autophagic flux upon ER stress, and sensitizes cells to apoptosis. TMEM33 invalidation in mice protects against renal ER stress.","method":"Co-immunoprecipitation, ER liposome-planar bilayer electrophysiology, mouse TMEM33 knockout, siRNA knockdown, calcium imaging, autophagy and apoptosis assays","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — direct ion channel reconstitution assay, reciprocal Co-IP, in vivo mouse KO, multiple orthogonal functional readouts","pmids":["31048699"],"is_preprint":false},{"year":2021,"finding":"TMEM33 acts as a negative regulator of virus-triggered interferon induction via two mechanisms: (1) it promotes K48-linked ubiquitination and degradation of MAVS; (2) it acts as a decoy substrate for TBK1, reducing phosphorylation of MITA/IRF3. TMEM33 co-localizes with and interacts with RLR cascade components at the ER. The N-terminal TM1 and TM2 domains of TMEM33 are required for IFN suppression.","method":"Co-immunoprecipitation, ubiquitination assays, kinase phosphorylation assays, domain deletion mutants, IFN promoter reporter assay, siRNA knockdown, zebrafish cell line overexpression","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 2 / Strong — two mechanistically distinct pathways each supported by biochemical assays (ubiquitination and phosphorylation), domain mapping, multiple methods in single study","pmids":["33600488"],"is_preprint":false},{"year":2021,"finding":"TMEM33 functions as a downstream effector of PKM2 in controlling lipid homeostasis. Loss of PKM2 upregulates TMEM33, which recruits the E3 ubiquitin ligase RNF5 to promote proteasomal degradation of SCAP (SREBP-cleavage activating protein), thereby reducing SREBP activation and lipid synthesis. TMEM33 transcription is controlled by NRF1, whose cleavage and activation are regulated by PKM2 levels.","method":"Co-immunoprecipitation, ubiquitination assay, protein stability assay, siRNA/shRNA knockdown, mouse PKM2 knockout, transcriptional reporter assays, immunoblotting","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — Co-IP identifies RNF5 recruitment to SCAP via TMEM33, functional ubiquitination/degradation assay, in vivo mouse KO validation, multiple orthogonal methods","pmids":["34487377"],"is_preprint":false},{"year":2025,"finding":"TMEM33 physically interacts with RAB22A and binds the TM2 domain of ER-shaping protein RTN4, forming a RAB22A/TMEM33/RTN4 complex. This assembly promotes RTN4 homo-oligomerization, generating RTN4-enriched microdomains of high ER curvature that drive bud scission of RTN4-positive vesicles. These vesicles develop into noncanonical autophagosomes that are secreted as extracellular vesicles via the Rafeesome pathway, constituting a secretory ER-phagy route that bypasses lysosomal degradation.","method":"Co-immunoprecipitation, domain mapping (TM2 binding), fluorescence microscopy, vesicle biogenesis assays, extracellular vesicle isolation, autophagy flux assays","journal":"Cell discovery","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP and domain mapping with functional vesicle biogenesis readouts, single lab, newly published","pmids":["40301304"],"is_preprint":false},{"year":2026,"finding":"TMEM33 deletion in CD8+ T cells enhances their anti-tumor function. Tmem33 knockout mice show delayed melanoma growth and increased CD8+ T cell infiltration. TMEM33 acts cell-intrinsically in CD8+ T cells to constrain TCF-1+PD-1+ progenitor-exhausted T cell (Tpex) maintenance; its deletion promotes Tpex accumulation, elevated effector function, and reduced exhaustion. Ex vivo deletion also enhanced polyclonal activation of naïve CD8+ T cells.","method":"Murine constitutive knockout, adoptive cell transfer (OT-I cells), flow cytometry, ex vivo T cell activation assays, B16F10-OVA tumor model","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean genetic KO with defined cellular phenotype in multiple experimental systems, preprint not yet peer-reviewed","pmids":["41509280"],"is_preprint":true}],"current_model":"TMEM33 is an ER-resident transmembrane protein that shapes ER/nuclear envelope architecture (via reticulon binding and amphipathic helix-mediated membrane curvature), regulates intracellular calcium homeostasis by enhancing polycystin-2 (PC2) channel activity at the ER, modulates the unfolded protein response by binding PERK and amplifying PERK/IRE1α signaling, controls lipid metabolism by recruiting RNF5 to ubiquitinate and degrade SCAP, suppresses antiviral interferon production by promoting MAVS degradation and acting as a TBK1 decoy substrate, initiates a secretory ER-phagy pathway through assembly of a RAB22A/TMEM33/RTN4 complex, and cell-intrinsically constrains progenitor-exhausted CD8+ T cell maintenance in tumors."},"narrative":{"mechanistic_narrative":"TMEM33 is a multi-pass endoplasmic reticulum (ER) transmembrane protein that shapes ER and nuclear envelope architecture and serves as a regulatory hub at the ER membrane for calcium signaling, the unfolded protein response, lipid homeostasis, and innate antiviral immunity [PMID:20498018, PMID:25612671, PMID:31048699]. Its membrane-shaping function is conserved: the yeast ortholog Pom33 associates with the reticulon Rtn1 and is required for proper nuclear pore complex distribution and density, with nuclear pore targeting achieved through both karyopherin (Kap123) binding and amphipathic α-helices that preferentially bind highly curved membranes [PMID:20498018, PMID:25413348]. Human TMEM33 binds multiple reticulons (RTN1A, RTN2B, RTN3C, RTN4C) and the reticulon-homology protein Arl6IP1, localizes to the ER and nuclear envelope, and suppresses reticulon-induced ER tubulation [PMID:25612671]. At the ER membrane TMEM33 interacts with the polycystin-2 (PC2) channel and enhances its calcium-conductance, thereby lowering ER calcium content, impairing lysosomal calcium refilling and autophagic flux, and sensitizing cells to ER-stress-induced apoptosis [PMID:31048699]; consistent with a calcium-signaling role, TMEM33 is required for VEGF-A-evoked cytosolic calcium oscillations that drive endothelial ERK/Notch signaling and developmental angiogenesis [PMID:30760708]. TMEM33 also amplifies the unfolded protein response by binding the ER kinase PERK and elevating PERK/IRE1α downstream effectors [PMID:26268696]. In lipid metabolism it acts downstream of the PKM2–NRF1 axis to recruit the E3 ligase RNF5 to ubiquitinate and degrade SCAP, dampening SREBP activation [PMID:34487377], and it negatively regulates virus-triggered interferon induction by promoting K48-linked ubiquitination and degradation of MAVS and acting as a decoy substrate for TBK1 [PMID:33600488].","teleology":[{"year":2010,"claim":"Established the founding cell-biological role of the TMEM33 family by showing the yeast ortholog Pom33 controls nuclear pore complex distribution and acts within the nuclear envelope architecture network.","evidence":"Yeast genetics (synthetic lethality, deletions), Co-IP and NPC distribution microscopy in budding yeast","pmids":["20498018"],"confidence":"High","gaps":["Did not define the membrane-shaping mechanism","Human ortholog function not addressed","Direct biochemical activity of Pom33 undefined"]},{"year":2014,"claim":"Resolved how the protein is targeted to and acts at curved membranes, identifying amphipathic α-helices that sense high membrane curvature and a karyopherin-binding mechanism for nuclear pore targeting.","evidence":"Co-IP/MS, in vitro binding, circular dichroism and liposome co-flotation, plus structure-function mutagenesis of the fission yeast ortholog Tts1","pmids":["25413348","25103238"],"confidence":"High","gaps":["Curvature-sensing established in yeast orthologs only","Did not connect curvature sensing to mammalian organelle functions","Catalytic activity, if any, not defined"]},{"year":2014,"claim":"Connected human TMEM33 to ER morphology by showing it binds multiple reticulons and counteracts reticulon-driven ER tubulation, linking it to the ER-shaping machinery.","evidence":"Affinity chromatography, Co-IP, immunofluorescence and ER morphology assays in human cells","pmids":["25612671"],"confidence":"Medium","gaps":["Single-lab finding","Mechanism of tubulation suppression not resolved","Functional consequence in vivo not tested"]},{"year":2015,"claim":"Implicated TMEM33 in the unfolded protein response by showing it is ER-stress-inducible, binds PERK, and amplifies PERK/IRE1α downstream signaling and stress-associated apoptosis/autophagy markers.","evidence":"Co-IP, fractionation and immunoblotting of UPR effectors under TMEM33 overexpression in breast cancer cells","pmids":["26268696"],"confidence":"Medium","gaps":["Largely overexpression-based","Direct effect on PERK kinase activity not shown","Single-lab"]},{"year":2019,"claim":"Defined a calcium-signaling function: TMEM33 enhances the ER channel polycystin-2 to regulate ER/lysosomal calcium and autophagy, and is required for VEGF-A-evoked calcium oscillations driving angiogenesis.","evidence":"ER liposome–planar bilayer electrophysiology, reciprocal Co-IP, mouse KO and zebrafish knockdown with calcium imaging and vascular development assays","pmids":["31048699","30760708"],"confidence":"High","gaps":["How TMEM33 modulates PC2 gating structurally is unresolved","Link between angiogenic calcium signaling and PC2 not directly tied together"]},{"year":2021,"claim":"Expanded TMEM33 into lipid homeostasis and innate immunity, defining E3-ligase scaffolding (RNF5→SCAP degradation) and dual antiviral suppression (MAVS degradation and TBK1 decoy).","evidence":"Co-IP, ubiquitination and kinase assays, domain-deletion mutants, mouse PKM2 KO and transcriptional reporters","pmids":["34487377","33600488"],"confidence":"High","gaps":["Whether these roles operate simultaneously or in distinct cell states is unclear","Direct enzymatic role of TMEM33 not established (acts as scaffold/decoy)"]},{"year":2025,"claim":"Linked TMEM33's curvature/reticulon biology to a secretory ER-phagy route, showing it assembles a RAB22A/TMEM33/RTN4 complex driving RTN4-enriched curved microdomains and vesicle scission.","evidence":"Reciprocal Co-IP, TM2 domain mapping, vesicle biogenesis and extracellular vesicle/autophagy flux assays","pmids":["40301304"],"confidence":"Medium","gaps":["Single-lab and newly published","How RAB22A recruits TMEM33 mechanistically is unresolved","Physiological role of the secretory route not established"]},{"year":2026,"claim":"Introduced a cell-intrinsic immunological role, showing TMEM33 constrains progenitor-exhausted CD8+ T cell maintenance and limits anti-tumor function.","evidence":"Murine constitutive KO, OT-I adoptive transfer, flow cytometry and B16F10-OVA tumor model (preprint)","pmids":["41509280"],"confidence":"Medium","gaps":["Preprint, not yet peer-reviewed","Molecular mechanism in T cells (which TMEM33 pathway) not defined","Link to ER/calcium/UPR roles untested"]},{"year":null,"claim":"It remains unknown how TMEM33's single membrane-shaping/curvature-sensing activity is mechanistically partitioned across its diverse roles in calcium, UPR, lipid, antiviral, and T-cell biology.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying structural model linking curvature sensing to channel/ligase/decoy functions","No high-resolution structure of human TMEM33","Whether functions are context- or tissue-specific is unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[1,2]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[6,4]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[8,9]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0,3]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[3,4,5,6,7]},{"term_id":"GO:0005635","term_label":"nuclear envelope","supporting_discovery_ids":[0,2,3]}],"pathway":[{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[4,6]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[7]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[8]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[6,9]},{"term_id":"R-HSA-1852241","term_label":"Organelle biogenesis and maintenance","supporting_discovery_ids":[0,2]}],"complexes":["RAB22A/TMEM33/RTN4 complex"],"partners":["RTN4","RTN1","ARL6IP1","PERK","PKD2","RNF5","MAVS","RAB22A"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P57088","full_name":"Transmembrane protein 33","aliases":["Protein DB83","SHINC-3"],"length_aa":247,"mass_kda":28.0,"function":"Acts as a regulator of the tubular endoplasmic reticulum (ER) network by modulating intracellular calcium homeostasis. Mechanistically, stimulates PKD2 calcium-dependent activity (By similarity). Suppresses the RTN3/4-induced formation of the ER tubules (PubMed:25612671). Positively regulates PERK-mediated and IRE1-mediated unfolded protein response signaling (PubMed:26268696). Plays an essential role in VEGF-mediated release of Ca(2+) from ER stores during angiogenesis (PubMed:30760708). Also plays a role in the modulation of innate immune signaling through the cGAS-STING pathway by interacting with RNF26 (PubMed:32614325). Participates in lipid metabolism by acting as a downstream effector of the pyruvate kinase/PKM. Forms a complex with RNF5 to facilitate polyubiquitination and subsequent degradation of SCAP on the ER membrane (PubMed:34487377)","subcellular_location":"Endoplasmic reticulum membrane; Melanosome; Nucleus envelope","url":"https://www.uniprot.org/uniprotkb/P57088/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/TMEM33","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CCDC47","stoichiometry":10.0},{"gene":"GOLT1B","stoichiometry":4.0},{"gene":"CANX","stoichiometry":0.2},{"gene":"COPB2","stoichiometry":0.2},{"gene":"DDOST","stoichiometry":0.2},{"gene":"EMC3","stoichiometry":0.2},{"gene":"MMGT1","stoichiometry":0.2},{"gene":"PGRMC1","stoichiometry":0.2},{"gene":"RER1","stoichiometry":0.2},{"gene":"VAPA","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/TMEM33","total_profiled":1310},"omim":[{"mim_id":"618515","title":"TRANSMEMBRANE PROTEIN 33; TMEM33","url":"https://www.omim.org/entry/618515"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/TMEM33"},"hgnc":{"alias_symbol":["FLJ10525","Pom33"],"prev_symbol":[]},"alphafold":{"accession":"P57088","domains":[{"cath_id":"-","chopping":"16-200","consensus_level":"high","plddt":91.2968,"start":16,"end":200},{"cath_id":"4.10.860","chopping":"202-247","consensus_level":"medium","plddt":91.3613,"start":202,"end":247}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P57088","model_url":"https://alphafold.ebi.ac.uk/files/AF-P57088-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P57088-F1-predicted_aligned_error_v6.png","plddt_mean":88.38},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TMEM33","jax_strain_url":"https://www.jax.org/strain/search?query=TMEM33"},"sequence":{"accession":"P57088","fasta_url":"https://rest.uniprot.org/uniprotkb/P57088.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P57088/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P57088"}},"corpus_meta":[{"pmid":"30760708","id":"PMC_30760708","title":"tmem33 is essential for VEGF-mediated endothelial calcium oscillations and angiogenesis.","date":"2019","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/30760708","citation_count":82,"is_preprint":false},{"pmid":"20498018","id":"PMC_20498018","title":"Pom33, a novel transmembrane nucleoporin required for proper nuclear pore complex distribution.","date":"2010","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/20498018","citation_count":78,"is_preprint":false},{"pmid":"34487377","id":"PMC_34487377","title":"PKM2-TMEM33 axis regulates lipid homeostasis in cancer cells by controlling SCAP stability.","date":"2021","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/34487377","citation_count":50,"is_preprint":false},{"pmid":"26268696","id":"PMC_26268696","title":"TMEM33: a new stress-inducible endoplasmic reticulum transmembrane protein and modulator of the unfolded protein response signaling.","date":"2015","source":"Breast cancer research and treatment","url":"https://pubmed.ncbi.nlm.nih.gov/26268696","citation_count":34,"is_preprint":false},{"pmid":"25103238","id":"PMC_25103238","title":"Tts1, the fission yeast homologue of the TMEM33 family, functions in NE remodeling during mitosis.","date":"2014","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/25103238","citation_count":29,"is_preprint":false},{"pmid":"25413348","id":"PMC_25413348","title":"Nuclear pore targeting of the yeast Pom33 nucleoporin depends on karyopherin and lipid binding.","date":"2014","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/25413348","citation_count":28,"is_preprint":false},{"pmid":"25612671","id":"PMC_25612671","title":"Identification and characterization of TMEM33 as a reticulon-binding protein.","date":"2014","source":"The Kobe journal of medical sciences","url":"https://pubmed.ncbi.nlm.nih.gov/25612671","citation_count":24,"is_preprint":false},{"pmid":"31048699","id":"PMC_31048699","title":"TMEM33 regulates intracellular calcium homeostasis in renal tubular epithelial cells.","date":"2019","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/31048699","citation_count":23,"is_preprint":false},{"pmid":"33600488","id":"PMC_33600488","title":"A novel role of Zebrafish TMEM33 in negative regulation of interferon production by two distinct mechanisms.","date":"2021","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/33600488","citation_count":23,"is_preprint":false},{"pmid":"34956484","id":"PMC_34956484","title":"MiR-103a-3p aggravates renal cell carcinoma by targeting TMEM33.","date":"2021","source":"American journal of translational research","url":"https://pubmed.ncbi.nlm.nih.gov/34956484","citation_count":7,"is_preprint":false},{"pmid":"38821373","id":"PMC_38821373","title":"miR-29a-5p rescues depressive-like behaviors in a CUMS-induced mouse model by facilitating microglia M2-polarization in the prefrontal cortex via TMEM33 suppression.","date":"2024","source":"Journal of affective disorders","url":"https://pubmed.ncbi.nlm.nih.gov/38821373","citation_count":7,"is_preprint":false},{"pmid":"40301304","id":"PMC_40301304","title":"The assembly of RAB22A/TMEM33/RTN4 initiates a secretory ER-phagy pathway.","date":"2025","source":"Cell discovery","url":"https://pubmed.ncbi.nlm.nih.gov/40301304","citation_count":5,"is_preprint":false},{"pmid":"34575720","id":"PMC_34575720","title":"Analysis of the Putative Nucleoporin POM33 in the Filamentous Fungus Sordaria macrospora.","date":"2021","source":"Journal of fungi (Basel, Switzerland)","url":"https://pubmed.ncbi.nlm.nih.gov/34575720","citation_count":4,"is_preprint":false},{"pmid":"38238886","id":"PMC_38238886","title":"Endoplasmic reticulum localized TMEM33 domain-containing protein is crucial for all life cycle stages of the malaria parasite.","date":"2024","source":"Molecular microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/38238886","citation_count":3,"is_preprint":false},{"pmid":"40191724","id":"PMC_40191724","title":"TMEM33, an oncogene regulated by miR-214-3p, promotes the progression of lung adenocarcinoma through the Wnt/β-catenin signaling pathway.","date":"2025","source":"Oncology research","url":"https://pubmed.ncbi.nlm.nih.gov/40191724","citation_count":2,"is_preprint":false},{"pmid":"41509280","id":"PMC_41509280","title":"TMEM33 deletion potentiates anti-tumor CD8+ T cell immunity.","date":"2026","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/41509280","citation_count":0,"is_preprint":false},{"pmid":"41981572","id":"PMC_41981572","title":"Decellularized extracellular matrix hydrogel-mediated EVs therapy alleviates diabetic erectile dysfunction by targeting the miR-203a-3p/TMEM33 Axis.","date":"2026","source":"Journal of nanobiotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/41981572","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10334,"output_tokens":3268,"usd":0.040011,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10767,"output_tokens":3440,"usd":0.069917,"stage2_stop_reason":"end_turn"},"total_usd":0.109928,"stage1_batch_id":"msgbatch_017qqVz33Ga63SCDwzb35XPb","stage2_batch_id":"msgbatch_01Scr2Ei9x4HJMiRGxwrmvLK","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2010,\n      \"finding\": \"Pom33 (yeast TMEM33 ortholog) is an integral transmembrane protein dynamically associated with nuclear pore complexes (NPCs) in budding yeast. Loss of Pom33 impairs NPC distribution and NPC density in the daughter nucleus, and Pom33 becomes essential for viability in the absence of the Nup84 complex or Ndc1 interaction network. Pom33 associates physically with the reticulon Rtn1.\",\n      \"method\": \"Yeast genetics (synthetic lethality, deletion mutants), co-immunoprecipitation, fluorescence microscopy of NPC distribution\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple genetic and cell biological methods in a focused study, independently foundational for the TMEM33 family\",\n      \"pmids\": [\"20498018\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Nuclear pore targeting of yeast Pom33 requires two redundant mechanisms: direct interaction of its C-terminal domain (CTD) with the karyopherin Kap123 (identified by Co-IP/MS and confirmed by in vitro binding assay), and membrane association via amphipathic α-helices in the CTD that preferentially bind highly curved lipid membranes (shown by circular dichroism and liposome co-flotation assays). Combined impairment of both lipid-binding and Kap123-binding abolishes NPC targeting.\",\n      \"method\": \"Co-immunoprecipitation/mass spectrometry, in vitro protein-protein binding, circular dichroism, liposome co-flotation, yeast mutant analysis\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — multiple orthogonal in vitro and in vivo methods establishing mechanism in a single rigorous study\",\n      \"pmids\": [\"25413348\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Fission yeast Tts1 (TMEM33 ortholog) localizes to high-curvature ER domains via an amphipathic helix in its C-terminus and functions in two distinct processes during closed mitosis: (1) promoting spindle pole body (SPB) insertion into the nuclear envelope (NE), dependent on conserved residues at the luminal interface of the third transmembrane region; and (2) modulating NPC distribution during mitotic NE expansion, dependent on the amphipathic helix.\",\n      \"method\": \"Fluorescence microscopy, domain mutagenesis, yeast deletion mutants, live-cell imaging\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — structure-function mutagenesis dissecting two distinct roles, multiple orthogonal methods\",\n      \"pmids\": [\"25103238\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Human TMEM33 was identified as a reticulon-binding protein by affinity chromatography. TMEM33 binds reticulon 4C, reticulon 1A, reticulon 2B, reticulon 3C, and the reticulon homology domain protein Arl6IP1. TMEM33 localizes to the ER membrane and nuclear envelope, co-localizes with reticulon 4C at ER sheets and partially at ER tubules, and exogenous TMEM33 expression suppresses reticulon 4C-induced ER tubulation.\",\n      \"method\": \"Affinity chromatography, co-immunoprecipitation, immunofluorescence microscopy, ER morphology assay\",\n      \"journal\": \"The Kobe journal of medical sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — multiple binding partners confirmed, functional ER tubulation suppression assay, single lab\",\n      \"pmids\": [\"25612671\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"TMEM33 is an ER stress-inducible transmembrane protein that localizes to the ER and physically binds PERK (an ER transmembrane kinase). Exogenous TMEM33 expression increases phosphorylation of eIF2α and IRE1α and elevates their downstream effectors ATF4-CHOP and XBP1-S, as well as apoptotic markers (cleaved caspase-7, cleaved PARP) and autophagosome marker LC3II.\",\n      \"method\": \"Immunoprecipitation, immunofluorescence, subcellular fractionation, immunoblotting, transient transfection\",\n      \"journal\": \"Breast cancer research and treatment\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — Co-IP identifies PERK binding, functional overexpression data with multiple readouts, single lab\",\n      \"pmids\": [\"26268696\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"TMEM33 localizes to the ER in zebrafish endothelial cells and is required for cytosolic calcium oscillations in response to VEGF-A. Global or endothelial-specific knockdown of tmem33 impairs ERK phosphorylation, Notch signaling, tip cell filopodia formation, endothelial cell migration, and embryonic vascular development.\",\n      \"method\": \"Zebrafish genetic knockdown (morpholino/CRISPR), live calcium imaging, siRNA knockdown in human ECs, immunofluorescence, in vivo vascular development assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple organisms (zebrafish and human ECs), multiple orthogonal functional readouts, specific calcium imaging and signaling assays\",\n      \"pmids\": [\"30760708\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"TMEM33 interacts with the ion channel polycystin-2 (PC2) at the ER membrane, enhancing PC2 channel opening across the physiological calcium range (demonstrated in ER liposomes fused to planar bilayers). Consequently, TMEM33 reduces intracellular calcium content in a PC2-dependent manner, impairs lysosomal calcium refilling, causes cathepsin translocation, inhibits autophagic flux upon ER stress, and sensitizes cells to apoptosis. TMEM33 invalidation in mice protects against renal ER stress.\",\n      \"method\": \"Co-immunoprecipitation, ER liposome-planar bilayer electrophysiology, mouse TMEM33 knockout, siRNA knockdown, calcium imaging, autophagy and apoptosis assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — direct ion channel reconstitution assay, reciprocal Co-IP, in vivo mouse KO, multiple orthogonal functional readouts\",\n      \"pmids\": [\"31048699\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"TMEM33 acts as a negative regulator of virus-triggered interferon induction via two mechanisms: (1) it promotes K48-linked ubiquitination and degradation of MAVS; (2) it acts as a decoy substrate for TBK1, reducing phosphorylation of MITA/IRF3. TMEM33 co-localizes with and interacts with RLR cascade components at the ER. The N-terminal TM1 and TM2 domains of TMEM33 are required for IFN suppression.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, kinase phosphorylation assays, domain deletion mutants, IFN promoter reporter assay, siRNA knockdown, zebrafish cell line overexpression\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — two mechanistically distinct pathways each supported by biochemical assays (ubiquitination and phosphorylation), domain mapping, multiple methods in single study\",\n      \"pmids\": [\"33600488\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"TMEM33 functions as a downstream effector of PKM2 in controlling lipid homeostasis. Loss of PKM2 upregulates TMEM33, which recruits the E3 ubiquitin ligase RNF5 to promote proteasomal degradation of SCAP (SREBP-cleavage activating protein), thereby reducing SREBP activation and lipid synthesis. TMEM33 transcription is controlled by NRF1, whose cleavage and activation are regulated by PKM2 levels.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, protein stability assay, siRNA/shRNA knockdown, mouse PKM2 knockout, transcriptional reporter assays, immunoblotting\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — Co-IP identifies RNF5 recruitment to SCAP via TMEM33, functional ubiquitination/degradation assay, in vivo mouse KO validation, multiple orthogonal methods\",\n      \"pmids\": [\"34487377\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"TMEM33 physically interacts with RAB22A and binds the TM2 domain of ER-shaping protein RTN4, forming a RAB22A/TMEM33/RTN4 complex. This assembly promotes RTN4 homo-oligomerization, generating RTN4-enriched microdomains of high ER curvature that drive bud scission of RTN4-positive vesicles. These vesicles develop into noncanonical autophagosomes that are secreted as extracellular vesicles via the Rafeesome pathway, constituting a secretory ER-phagy route that bypasses lysosomal degradation.\",\n      \"method\": \"Co-immunoprecipitation, domain mapping (TM2 binding), fluorescence microscopy, vesicle biogenesis assays, extracellular vesicle isolation, autophagy flux assays\",\n      \"journal\": \"Cell discovery\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP and domain mapping with functional vesicle biogenesis readouts, single lab, newly published\",\n      \"pmids\": [\"40301304\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"TMEM33 deletion in CD8+ T cells enhances their anti-tumor function. Tmem33 knockout mice show delayed melanoma growth and increased CD8+ T cell infiltration. TMEM33 acts cell-intrinsically in CD8+ T cells to constrain TCF-1+PD-1+ progenitor-exhausted T cell (Tpex) maintenance; its deletion promotes Tpex accumulation, elevated effector function, and reduced exhaustion. Ex vivo deletion also enhanced polyclonal activation of naïve CD8+ T cells.\",\n      \"method\": \"Murine constitutive knockout, adoptive cell transfer (OT-I cells), flow cytometry, ex vivo T cell activation assays, B16F10-OVA tumor model\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean genetic KO with defined cellular phenotype in multiple experimental systems, preprint not yet peer-reviewed\",\n      \"pmids\": [\"41509280\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"TMEM33 is an ER-resident transmembrane protein that shapes ER/nuclear envelope architecture (via reticulon binding and amphipathic helix-mediated membrane curvature), regulates intracellular calcium homeostasis by enhancing polycystin-2 (PC2) channel activity at the ER, modulates the unfolded protein response by binding PERK and amplifying PERK/IRE1α signaling, controls lipid metabolism by recruiting RNF5 to ubiquitinate and degrade SCAP, suppresses antiviral interferon production by promoting MAVS degradation and acting as a TBK1 decoy substrate, initiates a secretory ER-phagy pathway through assembly of a RAB22A/TMEM33/RTN4 complex, and cell-intrinsically constrains progenitor-exhausted CD8+ T cell maintenance in tumors.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TMEM33 is a multi-pass endoplasmic reticulum (ER) transmembrane protein that shapes ER and nuclear envelope architecture and serves as a regulatory hub at the ER membrane for calcium signaling, the unfolded protein response, lipid homeostasis, and innate antiviral immunity [#0, #3, #6]. Its membrane-shaping function is conserved: the yeast ortholog Pom33 associates with the reticulon Rtn1 and is required for proper nuclear pore complex distribution and density, with nuclear pore targeting achieved through both karyopherin (Kap123) binding and amphipathic α-helices that preferentially bind highly curved membranes [#0, #1]. Human TMEM33 binds multiple reticulons (RTN1A, RTN2B, RTN3C, RTN4C) and the reticulon-homology protein Arl6IP1, localizes to the ER and nuclear envelope, and suppresses reticulon-induced ER tubulation [#3]. At the ER membrane TMEM33 interacts with the polycystin-2 (PC2) channel and enhances its calcium-conductance, thereby lowering ER calcium content, impairing lysosomal calcium refilling and autophagic flux, and sensitizing cells to ER-stress-induced apoptosis [#6]; consistent with a calcium-signaling role, TMEM33 is required for VEGF-A-evoked cytosolic calcium oscillations that drive endothelial ERK/Notch signaling and developmental angiogenesis [#5]. TMEM33 also amplifies the unfolded protein response by binding the ER kinase PERK and elevating PERK/IRE1α downstream effectors [#4]. In lipid metabolism it acts downstream of the PKM2–NRF1 axis to recruit the E3 ligase RNF5 to ubiquitinate and degrade SCAP, dampening SREBP activation [#8], and it negatively regulates virus-triggered interferon induction by promoting K48-linked ubiquitination and degradation of MAVS and acting as a decoy substrate for TBK1 [#7].\"\n,\n  \"teleology\": [\n    {\n      \"year\": 2010,\n      \"claim\": \"Established the founding cell-biological role of the TMEM33 family by showing the yeast ortholog Pom33 controls nuclear pore complex distribution and acts within the nuclear envelope architecture network.\",\n      \"evidence\": \"Yeast genetics (synthetic lethality, deletions), Co-IP and NPC distribution microscopy in budding yeast\",\n      \"pmids\": [\"20498018\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not define the membrane-shaping mechanism\", \"Human ortholog function not addressed\", \"Direct biochemical activity of Pom33 undefined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Resolved how the protein is targeted to and acts at curved membranes, identifying amphipathic α-helices that sense high membrane curvature and a karyopherin-binding mechanism for nuclear pore targeting.\",\n      \"evidence\": \"Co-IP/MS, in vitro binding, circular dichroism and liposome co-flotation, plus structure-function mutagenesis of the fission yeast ortholog Tts1\",\n      \"pmids\": [\"25413348\", \"25103238\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Curvature-sensing established in yeast orthologs only\", \"Did not connect curvature sensing to mammalian organelle functions\", \"Catalytic activity, if any, not defined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Connected human TMEM33 to ER morphology by showing it binds multiple reticulons and counteracts reticulon-driven ER tubulation, linking it to the ER-shaping machinery.\",\n      \"evidence\": \"Affinity chromatography, Co-IP, immunofluorescence and ER morphology assays in human cells\",\n      \"pmids\": [\"25612671\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab finding\", \"Mechanism of tubulation suppression not resolved\", \"Functional consequence in vivo not tested\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Implicated TMEM33 in the unfolded protein response by showing it is ER-stress-inducible, binds PERK, and amplifies PERK/IRE1α downstream signaling and stress-associated apoptosis/autophagy markers.\",\n      \"evidence\": \"Co-IP, fractionation and immunoblotting of UPR effectors under TMEM33 overexpression in breast cancer cells\",\n      \"pmids\": [\"26268696\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Largely overexpression-based\", \"Direct effect on PERK kinase activity not shown\", \"Single-lab\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Defined a calcium-signaling function: TMEM33 enhances the ER channel polycystin-2 to regulate ER/lysosomal calcium and autophagy, and is required for VEGF-A-evoked calcium oscillations driving angiogenesis.\",\n      \"evidence\": \"ER liposome–planar bilayer electrophysiology, reciprocal Co-IP, mouse KO and zebrafish knockdown with calcium imaging and vascular development assays\",\n      \"pmids\": [\"31048699\", \"30760708\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How TMEM33 modulates PC2 gating structurally is unresolved\", \"Link between angiogenic calcium signaling and PC2 not directly tied together\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Expanded TMEM33 into lipid homeostasis and innate immunity, defining E3-ligase scaffolding (RNF5→SCAP degradation) and dual antiviral suppression (MAVS degradation and TBK1 decoy).\",\n      \"evidence\": \"Co-IP, ubiquitination and kinase assays, domain-deletion mutants, mouse PKM2 KO and transcriptional reporters\",\n      \"pmids\": [\"34487377\", \"33600488\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether these roles operate simultaneously or in distinct cell states is unclear\", \"Direct enzymatic role of TMEM33 not established (acts as scaffold/decoy)\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Linked TMEM33's curvature/reticulon biology to a secretory ER-phagy route, showing it assembles a RAB22A/TMEM33/RTN4 complex driving RTN4-enriched curved microdomains and vesicle scission.\",\n      \"evidence\": \"Reciprocal Co-IP, TM2 domain mapping, vesicle biogenesis and extracellular vesicle/autophagy flux assays\",\n      \"pmids\": [\"40301304\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab and newly published\", \"How RAB22A recruits TMEM33 mechanistically is unresolved\", \"Physiological role of the secretory route not established\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Introduced a cell-intrinsic immunological role, showing TMEM33 constrains progenitor-exhausted CD8+ T cell maintenance and limits anti-tumor function.\",\n      \"evidence\": \"Murine constitutive KO, OT-I adoptive transfer, flow cytometry and B16F10-OVA tumor model (preprint)\",\n      \"pmids\": [\"41509280\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Preprint, not yet peer-reviewed\", \"Molecular mechanism in T cells (which TMEM33 pathway) not defined\", \"Link to ER/calcium/UPR roles untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unknown how TMEM33's single membrane-shaping/curvature-sensing activity is mechanistically partitioned across its diverse roles in calcium, UPR, lipid, antiviral, and T-cell biology.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying structural model linking curvature sensing to channel/ligase/decoy functions\", \"No high-resolution structure of human TMEM33\", \"Whether functions are context- or tissue-specific is unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [6, 4]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [8, 9]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [3, 4, 5, 6, 7]},\n      {\"term_id\": \"GO:0005635\", \"supporting_discovery_ids\": [0, 2, 3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [4, 6]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [8]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [6, 9]},\n      {\"term_id\": \"R-HSA-1852241\", \"supporting_discovery_ids\": [0, 2]}\n    ],\n    \"complexes\": [\"RAB22A/TMEM33/RTN4 complex\"],\n    \"partners\": [\"RTN4\", \"RTN1\", \"ARL6IP1\", \"PERK\", \"PKD2\", \"RNF5\", \"MAVS\", \"RAB22A\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}