{"gene":"CLPTM1","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":2018,"finding":"Clptm1 interacts with all GABAA receptor subunits tested and promotes GABAAR trapping in the endoplasmic reticulum, thereby limiting forward trafficking of GABAARs to the cell surface. Overexpression of Clptm1 reduced GABAAR-mediated currents in recombinant systems, cultured hippocampal neurons, and brain, with no effect on glycine or AMPA receptor-mediated currents. Conversely, knockdown of Clptm1 increased phasic and tonic inhibitory transmission. Altering Clptm1 expression level mimicked activity-induced inhibitory synaptic scaling.","method":"Tandem affinity purification from transgenic mice expressing tagged GABAAR γ2 subunit + proteomic analysis; co-immunoprecipitation; whole-cell electrophysiology; shRNA knockdown and overexpression in cultured hippocampal neurons and in vivo","journal":"Neuron","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal co-IP, multiple orthogonal methods (proteomics, electrophysiology, KD, OE) across recombinant system, cultured neurons, and in vivo brain; independently confirmed by subsequent studies","pmids":["29395912"],"is_preprint":false},{"year":2024,"finding":"Genetic knockout of Clptm1 in mice elevated phasic and tonic inhibitory transmission. Haploinsufficiency of Clptm1 blocked high-frequency stimulation-induced long-term potentiation (LTP) at hippocampal CA3→CA1 synapses and impaired contextual fear memory. LTP and fear memory deficits were rescued by L-655,708, a negative allosteric modulator of the extrasynaptic GABAAR α5 subunit, implicating tonic inhibition as the primary driver.","method":"Clptm1 knockout mouse generation; whole-cell electrophysiology (mIPSC, LTP); contextual fear conditioning behavior; pharmacological rescue with L-655,708","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean genetic KO with defined cellular and behavioral phenotypes, pharmacological rescue experiment providing pathway placement, multiple orthogonal readouts","pmids":["38942471"],"is_preprint":false},{"year":2023,"finding":"Two de novo missense variants in CLPTM1 (p.R454H and p.R568Q) found in epilepsy patients reduced GABAAR current response amplitude, altered charge transfer, and changed the time course of desensitization and deactivation in HEK cells. The p.R568Q variant also significantly reduced surface expression of the GABAAR γ2 subunit.","method":"Whole-cell voltage-clamp and outside-out patch-clamp recordings in transiently transfected HEK cells; surface expression assay","journal":"Epilepsia","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro electrophysiology with two variants in heterologous expression system, surface expression corroboration, single lab","pmids":["37577761"],"is_preprint":false},{"year":2022,"finding":"In a PTZ-induced epilepsy rat model, Clptm1 expression was elevated. Downregulation of Clptm1 protected against PTZ-induced seizures, associated with increased GABAAR γ2 subunit surface expression and increased mIPSC amplitude, establishing Clptm1 as a modulator of GABAAR-mediated inhibitory synaptic transmission in vivo.","method":"PTZ rat epilepsy model; siRNA knockdown; western blot for surface GABAAR; whole-cell electrophysiology (mIPSC)","journal":"The Kaohsiung journal of medical sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo rat model with KD and multiple readouts (seizure behavior, surface expression, electrophysiology), single lab","pmids":["36519412"],"is_preprint":false},{"year":2023,"finding":"CLPTM1 interacts with the G protein-coupled estrogen receptor GPER1, as demonstrated by two orthogonal methods (APEX2-mediated proximity labeling and co-immunoprecipitation/mass spectrometry). PRKCSH and GANAB (subunits of α-glucosidase II) associate with CLPTM1 and potentially indirectly with GPER1. Imbalance in CLPTM1 levels induced nuclear association of GPER1.","method":"APEX2-mediated proximity labeling; co-immunoprecipitation followed by mass spectrometry; overexpression/knockdown with subcellular localization readout","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — two orthogonal interactome methods (APEX2 + IP-MS) with functional validation of GPER1 localization, single lab","pmids":["37947649"],"is_preprint":false},{"year":2023,"finding":"Loss of CLPTM1 weakens PGAP1-dependent GPI-inositol deacylation in the endoplasmic reticulum, resulting in partial PI-PLC resistance of GPI-anchored proteins. TMEM41B loss rescues this defect in CLPTM1-KO cells by stabilizing PGAP1 and delaying ER-to-Golgi transport, placing CLPTM1 in the pathway of GPI-anchor processing upstream of ER exit.","method":"CLPTM1 knockout cells; PI-PLC sensitivity assay; genetic epistasis with TMEM41B-KO; PGAP1 turnover assay","journal":"Journal of biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis with KO cells and biochemical PI-PLC assay, multiple cell lines, single lab","pmids":["37279648"],"is_preprint":false},{"year":1998,"finding":"CLPTM1 encodes a transmembrane protein ubiquitously expressed in adult tissues and in developing mouse embryos (day 10–12 by whole-mount in situ hybridization). The gene was identified by positional cloning at the chromosomal translocation breakpoint t(2;19)(q11.2;q13.3) in a family with cleft lip and palate.","method":"Positional cloning; Northern blot; whole-mount in situ hybridization; sequence analysis predicting transmembrane topology","journal":"Genomics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct cloning and expression characterization with multiple methods, foundational paper establishing gene identity and ubiquitous expression","pmids":["9828125"],"is_preprint":false},{"year":2001,"finding":"CRR9 (later recognized as a paralog of CLPTM1 with conserved C-terminus) was shown by transfection assay to sensitize the CDDP-sensitive ovarian tumor cell line 2008 to cisplatin-induced apoptosis rather than conferring resistance, placing CRR9/CLPTM1-family members in the regulation of cisplatin-induced apoptosis.","method":"mRNA differential display; 5'-RACE cloning; Northern blot; transfection assay with cisplatin sensitivity readout","journal":"Biochemical and biophysical research communications","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single transfection assay, single lab; finding is for CRR9 (paralog), mechanistic link to CLPTM1 itself is indirect via homology","pmids":["11162647"],"is_preprint":false}],"current_model":"CLPTM1 is a multi-pass transmembrane protein that localizes to the endoplasmic reticulum and Golgi network, where it directly interacts with GABAA receptor (GABAAR) subunits and traps them in the ER, thereby limiting forward trafficking of GABAARs to the synapse; loss of CLPTM1 increases both phasic and tonic inhibitory transmission, blocks LTP, and impairs hippocampus-dependent memory in mice, while gain-of-function reduces inhibitory currents — positioning CLPTM1 as a key regulator of inhibitory homeostatic plasticity. Additionally, CLPTM1 participates in ER quality control of GPI-anchored protein processing (modulating PGAP1-dependent GPI-inositol deacylation) and associates with the GPER1 estrogen receptor interactome, with CLPTM1 levels influencing GPER1 subcellular localization."},"narrative":{"mechanistic_narrative":"CLPTM1 is a multi-pass transmembrane protein that functions as a negative regulator of inhibitory neurotransmission by controlling the forward trafficking of GABAA receptors (GABAARs) from the endoplasmic reticulum to the cell surface [PMID:29395912]. It interacts directly with all tested GABAAR subunits and traps them in the ER; raising CLPTM1 levels suppresses GABAAR-mediated currents while lowering them increases both phasic and tonic inhibitory transmission, and this dose-dependent control mimics activity-induced inhibitory synaptic scaling [PMID:29395912]. Genetic loss in mice elevates inhibitory transmission, blocks hippocampal CA3→CA1 LTP, and impairs contextual fear memory, with the LTP and memory deficits rescued by negative allosteric modulation of the extrasynaptic α5-GABAAR — placing tonic inhibition as the driver of the CLPTM1 loss-of-function phenotype [PMID:38942471]. Consistent with this trafficking role, reducing CLPTM1 in a chemoconvulsant seizure model increases surface GABAAR γ2 and inhibitory current amplitude and is protective against seizures [PMID:36519412], and de novo missense variants found in epilepsy patients perturb GABAAR current kinetics and surface expression [PMID:37577761]. Beyond the synapse, CLPTM1 participates in ER quality control of GPI-anchored proteins, where its loss weakens PGAP1-dependent GPI-inositol deacylation upstream of ER exit [PMID:37279648], and it associates with the G protein-coupled estrogen receptor GPER1 interactome, with CLPTM1 abundance influencing GPER1 subcellular distribution [PMID:37947649]. The gene was originally identified by positional cloning at a cleft lip and palate translocation breakpoint as a ubiquitously expressed transmembrane protein [PMID:9828125].","teleology":[{"year":1998,"claim":"Established the gene's existence and basic nature — a ubiquitously expressed transmembrane protein — by mapping it to a cleft lip and palate translocation breakpoint, providing the molecular identity on which all later function rests.","evidence":"positional cloning, Northern blot, whole-mount in situ hybridization, and topology prediction","pmids":["9828125"],"confidence":"Medium","gaps":["No molecular function assigned","Causal role in cleft lip/palate not demonstrated beyond breakpoint association","Subcellular localization not directly resolved"]},{"year":2001,"claim":"First functional hint that a CLPTM1-family member modulates cell-death signaling, showing the paralog CRR9 sensitizes ovarian tumor cells to cisplatin-induced apoptosis.","evidence":"differential display cloning and transfection-based cisplatin sensitivity assay (finding pertains to the paralog CRR9)","pmids":["11162647"],"confidence":"Low","gaps":["Finding concerns the paralog, not CLPTM1 itself","Single transfection assay, single lab","No mechanism linking apoptosis sensitization to CLPTM1 molecular activity"]},{"year":2018,"claim":"Defined the core molecular function: CLPTM1 binds GABAAR subunits and retains them in the ER to limit surface delivery, establishing it as a dose-sensitive setpoint for inhibitory synaptic strength.","evidence":"tandem affinity purification + proteomics, reciprocal co-IP, whole-cell electrophysiology, and shRNA knockdown/overexpression in recombinant systems, cultured neurons, and brain","pmids":["29395912"],"confidence":"High","gaps":["Structural basis of subunit binding and ER retention not resolved","Whether retention is selective among GABAAR subtypes unclear","Mechanism coupling activity to CLPTM1 level not defined"]},{"year":2022,"claim":"Placed CLPTM1 in disease-relevant inhibitory control in vivo, showing it is upregulated in seizure and that its knockdown restores surface GABAAR and protects against seizures.","evidence":"PTZ rat epilepsy model with siRNA knockdown, surface GABAAR western blot, and mIPSC recordings","pmids":["36519412"],"confidence":"Medium","gaps":["Single lab and model","Mechanism of seizure-induced CLPTM1 upregulation unknown","Causal versus compensatory role of the upregulation not separated"]},{"year":2023,"claim":"Connected CLPTM1 to human epilepsy genetics by showing patient de novo missense variants alter GABAAR current kinetics and surface expression.","evidence":"whole-cell and outside-out patch-clamp plus surface expression assay of two variants in transfected HEK cells","pmids":["37577761"],"confidence":"Medium","gaps":["Heterologous system only, single lab","No in vivo or patient-neuron validation","Causality of variants for the clinical phenotype not formally established"]},{"year":2023,"claim":"Revealed a second, trafficking-related role in the ER: CLPTM1 supports PGAP1-dependent GPI-inositol deacylation upstream of ER exit, broadening its function beyond GABAARs.","evidence":"CLPTM1-knockout cells, PI-PLC sensitivity assay, TMEM41B epistasis, and PGAP1 turnover assay","pmids":["37279648"],"confidence":"Medium","gaps":["Direct molecular role (catalytic vs scaffolding) in deacylation unclear","Relationship between GPI processing role and GABAAR retention role unknown","Single lab"]},{"year":2023,"claim":"Expanded the interactome to GPER1 and α-glucosidase II subunits, indicating CLPTM1 influences receptor localization beyond GABAARs.","evidence":"APEX2 proximity labeling and IP-MS with overexpression/knockdown localization readout","pmids":["37947649"],"confidence":"Medium","gaps":["Whether GPER1 association is direct unresolved","Functional consequence of GPER1 nuclear redistribution unknown","Single lab"]},{"year":2024,"claim":"Tied CLPTM1's molecular function to circuit-level plasticity and behavior, showing knockout/haploinsufficiency blocks hippocampal LTP and contextual fear memory via excess tonic inhibition.","evidence":"Clptm1 knockout mice, mIPSC and LTP electrophysiology, contextual fear conditioning, and pharmacological rescue with the α5-GABAAR modulator L-655,708","pmids":["38942471"],"confidence":"High","gaps":["Cell-type and circuit specificity of the requirement not dissected","How CLPTM1 selectively gates extrasynaptic α5 receptors unclear","Developmental versus acute contribution not separated"]},{"year":null,"claim":"How CLPTM1's dual roles in GABAAR ER retention and GPI-anchor/receptor quality control are mechanistically and structurally unified remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of CLPTM1 or its substrate/cargo binding","Mechanism by which neuronal activity sets CLPTM1 level is unknown","Whether the GPI-processing and GABAAR-trafficking functions are mechanistically linked is undetermined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140313","term_label":"molecular sequestering activity","supporting_discovery_ids":[0]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[0,5]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[5]}],"pathway":[{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[0,1]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[0,5]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[5]}],"complexes":[],"partners":["GABRG2","GPER1","PRKCSH","GANAB","PGAP1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O96005","full_name":"Putative lipid scramblase CLPTM1","aliases":["Cleft lip and palate transmembrane protein 1"],"length_aa":669,"mass_kda":76.1,"function":"Involved in GABAergic but not glutamatergic transmission. Binds and traps GABAA receptors in the endoplasmic reticulum (ER). Modulates postsynaptic GABAergic transmission, and therefore inhibitory neurotransmission, by reducing the plasma membrane expression of these receptors. Altered GABAergic signaling is one among many causes of cleft palate (By similarity). Might function as a lipid scramblase, translocating lipids in membranes from one leaflet to the other one (By similarity). Required for efficient glycosylphosphatidylinositol (GPI) inositol deacylation in the ER, which is a crucial step to switch GPI-anchored proteins (GPI-APs) from protein folding to transport states (PubMed:29255114). May play a role in T-cell development (By similarity)","subcellular_location":"Membrane","url":"https://www.uniprot.org/uniprotkb/O96005/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CLPTM1","classification":"Not Classified","n_dependent_lines":8,"n_total_lines":1208,"dependency_fraction":0.006622516556291391},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000104853","cell_line_id":"CID001734","localizations":[{"compartment":"er","grade":3},{"compartment":"vesicles","grade":2}],"interactors":[{"gene":"AP3S1","stoichiometry":4.0},{"gene":"SEC61B","stoichiometry":4.0},{"gene":"CANX","stoichiometry":0.2},{"gene":"PGK1","stoichiometry":0.2},{"gene":"C4ORF32","stoichiometry":0.2},{"gene":"CCDC47","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID001734","total_profiled":1310},"omim":[{"mim_id":"612829","title":"RAS-ASSOCIATED PROTEIN RAB3C; RAB3C","url":"https://www.omim.org/entry/612829"},{"mim_id":"612585","title":"CLPTM1-LIKE PROTEIN; CLPTM1L","url":"https://www.omim.org/entry/612585"},{"mim_id":"604783","title":"CLEFT LIP AND PALATE-ASSOCIATED TRANSMEMBRANE PROTEIN 1; CLPTM1","url":"https://www.omim.org/entry/604783"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Endoplasmic reticulum","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/CLPTM1"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"O96005","domains":[{"cath_id":"-","chopping":"91-197_239-338","consensus_level":"high","plddt":84.3756,"start":91,"end":338}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O96005","model_url":"https://alphafold.ebi.ac.uk/files/AF-O96005-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O96005-F1-predicted_aligned_error_v6.png","plddt_mean":69.44},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CLPTM1","jax_strain_url":"https://www.jax.org/strain/search?query=CLPTM1"},"sequence":{"accession":"O96005","fasta_url":"https://rest.uniprot.org/uniprotkb/O96005.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O96005/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O96005"}},"corpus_meta":[{"pmid":"11162647","id":"PMC_11162647","title":"A novel gene, CRR9, which was up-regulated in CDDP-resistant ovarian tumor cell line, was associated with apoptosis.","date":"2001","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/11162647","citation_count":127,"is_preprint":false},{"pmid":"20597107","id":"PMC_20597107","title":"The association of telomere length and genetic variation in telomere biology genes.","date":"2010","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/20597107","citation_count":95,"is_preprint":false},{"pmid":"29395912","id":"PMC_29395912","title":"Clptm1 Limits Forward Trafficking of GABAA Receptors to Scale Inhibitory Synaptic Strength.","date":"2018","source":"Neuron","url":"https://pubmed.ncbi.nlm.nih.gov/29395912","citation_count":67,"is_preprint":false},{"pmid":"9828125","id":"PMC_9828125","title":"Characterization of a novel gene disrupted by a balanced chromosomal translocation t(2;19)(q11.2;q13.3) in a family with cleft lip and palate.","date":"1998","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/9828125","citation_count":60,"is_preprint":false},{"pmid":"33947463","id":"PMC_33947463","title":"Multi-tissue neocortical transcriptome-wide association study implicates 8 genes across 6 genomic loci in Alzheimer's disease.","date":"2021","source":"Genome medicine","url":"https://pubmed.ncbi.nlm.nih.gov/33947463","citation_count":57,"is_preprint":false},{"pmid":"19937600","id":"PMC_19937600","title":"Testing reported associations of genetic risk factors for oral clefts in a large Irish study population.","date":"2010","source":"Birth defects research. 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biology","url":"https://pubmed.ncbi.nlm.nih.gov/41959118","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":20719,"output_tokens":2371,"usd":0.048861,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9483,"output_tokens":3130,"usd":0.062832,"stage2_stop_reason":"end_turn"},"total_usd":0.111693,"stage1_batch_id":"msgbatch_01ACAxJQabDsht39JXeWG22d","stage2_batch_id":"msgbatch_01QEU22A9U5sbPTgsMzTmvSf","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2018,\n      \"finding\": \"Clptm1 interacts with all GABAA receptor subunits tested and promotes GABAAR trapping in the endoplasmic reticulum, thereby limiting forward trafficking of GABAARs to the cell surface. Overexpression of Clptm1 reduced GABAAR-mediated currents in recombinant systems, cultured hippocampal neurons, and brain, with no effect on glycine or AMPA receptor-mediated currents. Conversely, knockdown of Clptm1 increased phasic and tonic inhibitory transmission. Altering Clptm1 expression level mimicked activity-induced inhibitory synaptic scaling.\",\n      \"method\": \"Tandem affinity purification from transgenic mice expressing tagged GABAAR γ2 subunit + proteomic analysis; co-immunoprecipitation; whole-cell electrophysiology; shRNA knockdown and overexpression in cultured hippocampal neurons and in vivo\",\n      \"journal\": \"Neuron\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal co-IP, multiple orthogonal methods (proteomics, electrophysiology, KD, OE) across recombinant system, cultured neurons, and in vivo brain; independently confirmed by subsequent studies\",\n      \"pmids\": [\"29395912\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Genetic knockout of Clptm1 in mice elevated phasic and tonic inhibitory transmission. Haploinsufficiency of Clptm1 blocked high-frequency stimulation-induced long-term potentiation (LTP) at hippocampal CA3→CA1 synapses and impaired contextual fear memory. LTP and fear memory deficits were rescued by L-655,708, a negative allosteric modulator of the extrasynaptic GABAAR α5 subunit, implicating tonic inhibition as the primary driver.\",\n      \"method\": \"Clptm1 knockout mouse generation; whole-cell electrophysiology (mIPSC, LTP); contextual fear conditioning behavior; pharmacological rescue with L-655,708\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean genetic KO with defined cellular and behavioral phenotypes, pharmacological rescue experiment providing pathway placement, multiple orthogonal readouts\",\n      \"pmids\": [\"38942471\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Two de novo missense variants in CLPTM1 (p.R454H and p.R568Q) found in epilepsy patients reduced GABAAR current response amplitude, altered charge transfer, and changed the time course of desensitization and deactivation in HEK cells. The p.R568Q variant also significantly reduced surface expression of the GABAAR γ2 subunit.\",\n      \"method\": \"Whole-cell voltage-clamp and outside-out patch-clamp recordings in transiently transfected HEK cells; surface expression assay\",\n      \"journal\": \"Epilepsia\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro electrophysiology with two variants in heterologous expression system, surface expression corroboration, single lab\",\n      \"pmids\": [\"37577761\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"In a PTZ-induced epilepsy rat model, Clptm1 expression was elevated. Downregulation of Clptm1 protected against PTZ-induced seizures, associated with increased GABAAR γ2 subunit surface expression and increased mIPSC amplitude, establishing Clptm1 as a modulator of GABAAR-mediated inhibitory synaptic transmission in vivo.\",\n      \"method\": \"PTZ rat epilepsy model; siRNA knockdown; western blot for surface GABAAR; whole-cell electrophysiology (mIPSC)\",\n      \"journal\": \"The Kaohsiung journal of medical sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo rat model with KD and multiple readouts (seizure behavior, surface expression, electrophysiology), single lab\",\n      \"pmids\": [\"36519412\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"CLPTM1 interacts with the G protein-coupled estrogen receptor GPER1, as demonstrated by two orthogonal methods (APEX2-mediated proximity labeling and co-immunoprecipitation/mass spectrometry). PRKCSH and GANAB (subunits of α-glucosidase II) associate with CLPTM1 and potentially indirectly with GPER1. Imbalance in CLPTM1 levels induced nuclear association of GPER1.\",\n      \"method\": \"APEX2-mediated proximity labeling; co-immunoprecipitation followed by mass spectrometry; overexpression/knockdown with subcellular localization readout\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — two orthogonal interactome methods (APEX2 + IP-MS) with functional validation of GPER1 localization, single lab\",\n      \"pmids\": [\"37947649\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Loss of CLPTM1 weakens PGAP1-dependent GPI-inositol deacylation in the endoplasmic reticulum, resulting in partial PI-PLC resistance of GPI-anchored proteins. TMEM41B loss rescues this defect in CLPTM1-KO cells by stabilizing PGAP1 and delaying ER-to-Golgi transport, placing CLPTM1 in the pathway of GPI-anchor processing upstream of ER exit.\",\n      \"method\": \"CLPTM1 knockout cells; PI-PLC sensitivity assay; genetic epistasis with TMEM41B-KO; PGAP1 turnover assay\",\n      \"journal\": \"Journal of biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis with KO cells and biochemical PI-PLC assay, multiple cell lines, single lab\",\n      \"pmids\": [\"37279648\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"CLPTM1 encodes a transmembrane protein ubiquitously expressed in adult tissues and in developing mouse embryos (day 10–12 by whole-mount in situ hybridization). The gene was identified by positional cloning at the chromosomal translocation breakpoint t(2;19)(q11.2;q13.3) in a family with cleft lip and palate.\",\n      \"method\": \"Positional cloning; Northern blot; whole-mount in situ hybridization; sequence analysis predicting transmembrane topology\",\n      \"journal\": \"Genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct cloning and expression characterization with multiple methods, foundational paper establishing gene identity and ubiquitous expression\",\n      \"pmids\": [\"9828125\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"CRR9 (later recognized as a paralog of CLPTM1 with conserved C-terminus) was shown by transfection assay to sensitize the CDDP-sensitive ovarian tumor cell line 2008 to cisplatin-induced apoptosis rather than conferring resistance, placing CRR9/CLPTM1-family members in the regulation of cisplatin-induced apoptosis.\",\n      \"method\": \"mRNA differential display; 5'-RACE cloning; Northern blot; transfection assay with cisplatin sensitivity readout\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single transfection assay, single lab; finding is for CRR9 (paralog), mechanistic link to CLPTM1 itself is indirect via homology\",\n      \"pmids\": [\"11162647\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CLPTM1 is a multi-pass transmembrane protein that localizes to the endoplasmic reticulum and Golgi network, where it directly interacts with GABAA receptor (GABAAR) subunits and traps them in the ER, thereby limiting forward trafficking of GABAARs to the synapse; loss of CLPTM1 increases both phasic and tonic inhibitory transmission, blocks LTP, and impairs hippocampus-dependent memory in mice, while gain-of-function reduces inhibitory currents — positioning CLPTM1 as a key regulator of inhibitory homeostatic plasticity. Additionally, CLPTM1 participates in ER quality control of GPI-anchored protein processing (modulating PGAP1-dependent GPI-inositol deacylation) and associates with the GPER1 estrogen receptor interactome, with CLPTM1 levels influencing GPER1 subcellular localization.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CLPTM1 is a multi-pass transmembrane protein that functions as a negative regulator of inhibitory neurotransmission by controlling the forward trafficking of GABAA receptors (GABAARs) from the endoplasmic reticulum to the cell surface [#0]. It interacts directly with all tested GABAAR subunits and traps them in the ER; raising CLPTM1 levels suppresses GABAAR-mediated currents while lowering them increases both phasic and tonic inhibitory transmission, and this dose-dependent control mimics activity-induced inhibitory synaptic scaling [#0]. Genetic loss in mice elevates inhibitory transmission, blocks hippocampal CA3→CA1 LTP, and impairs contextual fear memory, with the LTP and memory deficits rescued by negative allosteric modulation of the extrasynaptic α5-GABAAR — placing tonic inhibition as the driver of the CLPTM1 loss-of-function phenotype [#1]. Consistent with this trafficking role, reducing CLPTM1 in a chemoconvulsant seizure model increases surface GABAAR γ2 and inhibitory current amplitude and is protective against seizures [#3], and de novo missense variants found in epilepsy patients perturb GABAAR current kinetics and surface expression [#2]. Beyond the synapse, CLPTM1 participates in ER quality control of GPI-anchored proteins, where its loss weakens PGAP1-dependent GPI-inositol deacylation upstream of ER exit [#5], and it associates with the G protein-coupled estrogen receptor GPER1 interactome, with CLPTM1 abundance influencing GPER1 subcellular distribution [#4]. The gene was originally identified by positional cloning at a cleft lip and palate translocation breakpoint as a ubiquitously expressed transmembrane protein [#6].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Established the gene's existence and basic nature — a ubiquitously expressed transmembrane protein — by mapping it to a cleft lip and palate translocation breakpoint, providing the molecular identity on which all later function rests.\",\n      \"evidence\": \"positional cloning, Northern blot, whole-mount in situ hybridization, and topology prediction\",\n      \"pmids\": [\"9828125\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No molecular function assigned\", \"Causal role in cleft lip/palate not demonstrated beyond breakpoint association\", \"Subcellular localization not directly resolved\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"First functional hint that a CLPTM1-family member modulates cell-death signaling, showing the paralog CRR9 sensitizes ovarian tumor cells to cisplatin-induced apoptosis.\",\n      \"evidence\": \"differential display cloning and transfection-based cisplatin sensitivity assay (finding pertains to the paralog CRR9)\",\n      \"pmids\": [\"11162647\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Finding concerns the paralog, not CLPTM1 itself\", \"Single transfection assay, single lab\", \"No mechanism linking apoptosis sensitization to CLPTM1 molecular activity\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined the core molecular function: CLPTM1 binds GABAAR subunits and retains them in the ER to limit surface delivery, establishing it as a dose-sensitive setpoint for inhibitory synaptic strength.\",\n      \"evidence\": \"tandem affinity purification + proteomics, reciprocal co-IP, whole-cell electrophysiology, and shRNA knockdown/overexpression in recombinant systems, cultured neurons, and brain\",\n      \"pmids\": [\"29395912\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of subunit binding and ER retention not resolved\", \"Whether retention is selective among GABAAR subtypes unclear\", \"Mechanism coupling activity to CLPTM1 level not defined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Placed CLPTM1 in disease-relevant inhibitory control in vivo, showing it is upregulated in seizure and that its knockdown restores surface GABAAR and protects against seizures.\",\n      \"evidence\": \"PTZ rat epilepsy model with siRNA knockdown, surface GABAAR western blot, and mIPSC recordings\",\n      \"pmids\": [\"36519412\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab and model\", \"Mechanism of seizure-induced CLPTM1 upregulation unknown\", \"Causal versus compensatory role of the upregulation not separated\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Connected CLPTM1 to human epilepsy genetics by showing patient de novo missense variants alter GABAAR current kinetics and surface expression.\",\n      \"evidence\": \"whole-cell and outside-out patch-clamp plus surface expression assay of two variants in transfected HEK cells\",\n      \"pmids\": [\"37577761\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Heterologous system only, single lab\", \"No in vivo or patient-neuron validation\", \"Causality of variants for the clinical phenotype not formally established\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Revealed a second, trafficking-related role in the ER: CLPTM1 supports PGAP1-dependent GPI-inositol deacylation upstream of ER exit, broadening its function beyond GABAARs.\",\n      \"evidence\": \"CLPTM1-knockout cells, PI-PLC sensitivity assay, TMEM41B epistasis, and PGAP1 turnover assay\",\n      \"pmids\": [\"37279648\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct molecular role (catalytic vs scaffolding) in deacylation unclear\", \"Relationship between GPI processing role and GABAAR retention role unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Expanded the interactome to GPER1 and α-glucosidase II subunits, indicating CLPTM1 influences receptor localization beyond GABAARs.\",\n      \"evidence\": \"APEX2 proximity labeling and IP-MS with overexpression/knockdown localization readout\",\n      \"pmids\": [\"37947649\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether GPER1 association is direct unresolved\", \"Functional consequence of GPER1 nuclear redistribution unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Tied CLPTM1's molecular function to circuit-level plasticity and behavior, showing knockout/haploinsufficiency blocks hippocampal LTP and contextual fear memory via excess tonic inhibition.\",\n      \"evidence\": \"Clptm1 knockout mice, mIPSC and LTP electrophysiology, contextual fear conditioning, and pharmacological rescue with the α5-GABAAR modulator L-655,708\",\n      \"pmids\": [\"38942471\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cell-type and circuit specificity of the requirement not dissected\", \"How CLPTM1 selectively gates extrasynaptic α5 receptors unclear\", \"Developmental versus acute contribution not separated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How CLPTM1's dual roles in GABAAR ER retention and GPI-anchor/receptor quality control are mechanistically and structurally unified remains unresolved.\",\n      \"evidence\": null,\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of CLPTM1 or its substrate/cargo binding\", \"Mechanism by which neuronal activity sets CLPTM1 level is unknown\", \"Whether the GPI-processing and GABAAR-trafficking functions are mechanistically linked is undetermined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140313\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [0, 5]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [0, 5]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"GABRG2\", \"GPER1\", \"PRKCSH\", \"GANAB\", \"PGAP1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}