{"gene":"MAJIN","run_date":"2026-06-10T02:59:50","timeline":{"discoveries":[{"year":2015,"finding":"MAJIN is a putative transmembrane protein of the inner nuclear membrane (INM) that, together with TERB1 and TERB2, forms a meiotic telomere complex. TERB1/2-MAJIN initially assembles on the INM sequestered by MAJIN. In early meiosis, a chimeric complex of TERB1/2-MAJIN and shelterin is formed; during prophase this matures into DNA-bound TERB1/2-MAJIN by releasing shelterin ('telomere cap exchange'), creating a direct link between telomeric DNA and the INM. These processes are regulated by CDK-dependent phosphorylation and the DNA-binding activity of MAJIN.","method":"Co-immunoprecipitation, mouse germ-cell genetics (knockout mice), live-cell and immunofluorescence imaging, biochemical fractionation, functional mutagenesis","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (Co-IP, KO mice, localization, mutagenesis) in a single focused study; independently replicated by subsequent structural studies","pmids":["26548954"],"is_preprint":false},{"year":2018,"finding":"Crystal structure of the MAJIN-TERB2 complex reveals a 2:2 hetero-tetramer that binds strongly to DNA and is tethered through long flexible linkers to the inner nuclear membrane and two TRF1-binding TERB2-TERB1 complexes. Structured illumination microscopy and biochemical studies show that MAJIN-TERB2-TERB1 recruits telomere-bound TRF1, which is then displaced during pachytene, allowing MAJIN-TERB2-TERB1 to bind telomeric DNA directly and form a mature attachment plate.","method":"X-ray crystallography, X-ray scattering, structured illumination microscopy, in vitro DNA-binding assays","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus orthogonal biophysical and microscopy methods; consistent with and extends findings of PMID:26548954","pmids":["30559341"],"is_preprint":false},{"year":2019,"finding":"Crystal structures of human TERB1-TERB2 and TERB2-MAJIN subcomplexes were determined. Specific disruption of the TERB2-MAJIN interaction in mouse Terb2 knock-in mice abolishes telomere attachment to the nuclear envelope and causes aberrant homologous pairing and disordered synapsis, establishing that direct TERB2-MAJIN protein-protein interaction is required for meiotic telomere-NE tethering.","method":"X-ray crystallography, knock-in mouse genetics with point mutations disrupting TERB2-MAJIN interface, immunofluorescence for telomere attachment and synapsis","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure combined with in vivo genetic disruption and defined cellular phenotype; independent study replicating the complex requirement","pmids":["30718482"],"is_preprint":false},{"year":2017,"finding":"TRF1 directs the assembly of TERB1-TERB2-MAJIN on telomeres in vivo; germ-cell-specific TRF1 knockout eliminates TERB1-TERB2-MAJIN telomere localization. TERB2 and MAJIN do not mediate cohesin recruitment at telomeres; that function is confined to the MYB-like domain of TERB1.","method":"Germ-cell-specific TRF1 conditional knockout mice, co-immunoprecipitation, immunofluorescence","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean conditional KO with defined assembly phenotype plus Co-IP domain mapping; two orthogonal approaches","pmids":["29141207"],"is_preprint":false},{"year":2020,"finding":"SUN1 interacts directly with MAJIN (and with TERB1) at the nuclear envelope; the SUN1-MAJIN interaction is stronger than the SUN1-TERB1 interaction. Both MAJIN and the CDK2-activator SPDYA bind to the N-terminal domain of SUN1 at overlapping sites. CDK2 inhibition decreases the SUN1-MAJIN interaction, suggesting CDK2-dependent phosphorylation promotes telomere-NE attachment via SUN1-MAJIN.","method":"Co-immunoprecipitation, GST pulldown, binding-site mapping with truncation constructs, CDK2 inhibitor treatment","journal":"Frontiers in cell and developmental biology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — Co-IP and pulldown mapping in a single lab, supported by inhibitor data but no structural validation or in vivo genetic confirmation of the SUN1-MAJIN interface","pmids":["33015044"],"is_preprint":false},{"year":2022,"finding":"The TERB1 MYB domain does not mediate telomere localization of the downstream TERB2-MAJIN complex; Terb1 point-mutant mice lacking MYB DNA-binding activity show normal TERB2-MAJIN telomere localization. Instead, the MYB domain regulates cohesin enrichment and axial element remodeling at telomeres in the early-to-late pachytene transition, suppressing telomere erosion.","method":"Terb1 point-mutant knock-in mice, immunofluorescence for TERB2/MAJIN localization, cohesin and synaptonemal complex markers, telomere length analysis","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean knock-in genetics with defined phenotypic readouts for MAJIN localization; single lab, single study","pmids":["35081355"],"is_preprint":false}],"current_model":"MAJIN is a meiosis-specific inner nuclear membrane protein that anchors telomeres to the nuclear envelope by forming a 2:2 hetero-tetrameric complex with TERB2, whose structure is established by crystallography; this MAJIN-TERB2 core is linked via long flexible linkers to TERB1 (which binds TRF1) and to SUN1 at the NE, and the entire TERB1-TERB2-MAJIN (TTM) complex undergoes a CDK-regulated 'telomere cap exchange'—first co-assembling with shelterin/TRF1 at the INM then displacing shelterin to bind telomeric DNA directly—thereby transmitting cytoskeletal forces through the LINC complex to drive chromosome movements required for homolog pairing and recombination."},"narrative":{"mechanistic_narrative":"MAJIN is a meiosis-specific inner nuclear membrane protein that physically tethers telomeres to the nuclear envelope to enable the chromosome movements underlying homolog pairing and recombination [PMID:26548954]. As a putative transmembrane component of the inner nuclear membrane, MAJIN nucleates assembly of the meiotic telomere complex by sequestering TERB1 and TERB2 at the membrane, where the complex first forms a chimeric assembly with shelterin and then matures into a DNA-bound state by releasing shelterin in a CDK-phosphorylation-regulated 'telomere cap exchange' [PMID:26548954]. Structurally, MAJIN and TERB2 form a 2:2 hetero-tetramer that binds DNA directly and is joined through long flexible linkers to TERB1, which engages telomere-bound TRF1; TRF1 is displaced during pachytene to allow the MAJIN-TERB2-TERB1 module to grip telomeric DNA and form a mature attachment plate [PMID:30559341]. The direct TERB2-MAJIN protein-protein interaction is essential in vivo: disrupting this interface in mice abolishes telomere-nuclear envelope tethering and produces aberrant homolog pairing and disordered synapsis [PMID:30718482]. Telomeric recruitment of the complex is directed by TRF1, since germ-cell TRF1 loss eliminates TERB1-TERB2-MAJIN telomere localization [PMID:29141207], and MAJIN connects this module to the LINC complex by binding directly to SUN1 at the nuclear envelope in a CDK2-promoted manner [PMID:33015044].","teleology":[{"year":2015,"claim":"Established MAJIN as a meiosis-specific INM protein and defined the core logic of meiotic telomere attachment, answering how telomeres become physically coupled to the nuclear envelope.","evidence":"Co-IP, knockout mouse germ-cell genetics, imaging, fractionation, and functional mutagenesis in mouse","pmids":["26548954"],"confidence":"High","gaps":["Atomic basis of the MAJIN-TERB2 interaction not resolved","Molecular trigger and ordering of the shelterin-to-DNA cap exchange not fully defined"]},{"year":2017,"claim":"Showed that TRF1 directs telomeric assembly of the TERB1-TERB2-MAJIN complex and separated MAJIN/TERB2 from the cohesin-recruiting function, clarifying the division of labor within the complex.","evidence":"Germ-cell-specific TRF1 conditional knockout mice, Co-IP, and immunofluorescence","pmids":["29141207"],"confidence":"High","gaps":["How TRF1 recruitment is handed off during cap exchange not mechanistically detailed","Does not address MAJIN membrane topology"]},{"year":2018,"claim":"Resolved the 2:2 MAJIN-TERB2 hetero-tetramer and its DNA-binding capacity, explaining structurally how the complex tethers via flexible linkers and grips telomeric DNA after TRF1 displacement.","evidence":"X-ray crystallography, X-ray scattering, structured illumination microscopy, and in vitro DNA-binding assays","pmids":["30559341"],"confidence":"High","gaps":["Structure of full-length membrane-embedded MAJIN not determined","Conformational changes during cap exchange not captured"]},{"year":2019,"claim":"Demonstrated that the direct TERB2-MAJIN interface is genetically required for telomere-NE tethering and proper synapsis, converting the structural model into an in vivo functional requirement.","evidence":"Crystal structures of human TERB1-TERB2 and TERB2-MAJIN subcomplexes plus interface-disrupting knock-in mouse genetics with synapsis readouts","pmids":["30718482"],"confidence":"High","gaps":["Quantitative contribution of MAJIN DNA-binding versus TERB2 binding to attachment strength not separated"]},{"year":2020,"claim":"Identified a direct MAJIN-SUN1 interaction at the nuclear envelope and its CDK2 dependence, providing the molecular link between the telomere complex and the LINC complex.","evidence":"Co-IP, GST pulldown, truncation-based binding-site mapping, and CDK2 inhibitor treatment","pmids":["33015044"],"confidence":"Medium","gaps":["No structural validation of the SUN1-MAJIN interface","No in vivo genetic confirmation of the interaction's functional requirement"]},{"year":2022,"claim":"Distinguished the TERB1 MYB domain's role from MAJIN/TERB2 localization, showing that MYB DNA-binding is dispensable for TERB2-MAJIN telomere recruitment and instead controls cohesin and axial element remodeling.","evidence":"Terb1 MYB point-mutant knock-in mice with MAJIN/TERB2 localization, cohesin, synaptonemal, and telomere-length readouts","pmids":["35081355"],"confidence":"Medium","gaps":["Single lab, single study","Does not define what within the complex independently anchors TERB2-MAJIN to telomeres after TRF1 handoff"]},{"year":null,"claim":"The precise molecular trigger that drives the shelterin-to-direct-DNA cap exchange and the force-transmission dynamics from SUN1/LINC through MAJIN to moving telomeres remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["Real-time mechanics of cap exchange not visualized","In vivo necessity of the SUN1-MAJIN interface not genetically tested","Membrane topology of MAJIN not structurally confirmed"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0003677","term_label":"DNA binding","supporting_discovery_ids":[0,1]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,2,4]}],"localization":[{"term_id":"GO:0005635","term_label":"nuclear envelope","supporting_discovery_ids":[0,1,2,4]}],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[0,2]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[0]}],"complexes":["TERB1-TERB2-MAJIN (TTM) complex","LINC complex (via SUN1)"],"partners":["TERB2","TERB1","TRF1","SUN1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q3KP22","full_name":"Membrane-anchored junction protein","aliases":[],"length_aa":176,"mass_kda":20.1,"function":"Meiosis-specific telomere-associated protein involved in meiotic telomere attachment to the nucleus inner membrane, a crucial step for homologous pairing and synapsis. Component of the MAJIN-TERB1-TERB2 complex, which promotes telomere cap exchange by mediating attachment of telomeric DNA to the inner nuclear membrane and replacement of the protective cap of telomeric chromosomes: in early meiosis, the MAJIN-TERB1-TERB2 complex associates with telomeric DNA and the shelterin/telosome complex. During prophase, the complex matures and promotes release of the shelterin/telosome complex from telomeric DNA. In the complex, MAJIN acts as the anchoring subunit to the nucleus inner membrane. MAJIN shows DNA-binding activity, possibly for the stabilization of telomere attachment on the nucleus inner membrane","subcellular_location":"Nucleus inner membrane; Chromosome, telomere","url":"https://www.uniprot.org/uniprotkb/Q3KP22/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MAJIN","classification":"Not Classified","n_dependent_lines":16,"n_total_lines":1208,"dependency_fraction":0.013245033112582781},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/MAJIN","total_profiled":1310},"omim":[{"mim_id":"619646","title":"SPERMATOGENIC FAILURE 60; SPGF60","url":"https://www.omim.org/entry/619646"},{"mim_id":"619645","title":"SPERMATOGENIC FAILURE 59; SPGF59","url":"https://www.omim.org/entry/619645"},{"mim_id":"617332","title":"TELOMERE REPEAT-BINDING BOUQUET FORMATION PROTEIN 1; TERB1","url":"https://www.omim.org/entry/617332"},{"mim_id":"617131","title":"TELOMERE REPEAT-BINDING BOUQUET FORMATION PROTEIN 2; TERB2","url":"https://www.omim.org/entry/617131"},{"mim_id":"617130","title":"MEMBRANE-ANCHORED JUNCTION PROTEIN; MAJIN","url":"https://www.omim.org/entry/617130"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"testis","ntpm":21.0}],"url":"https://www.proteinatlas.org/search/MAJIN"},"hgnc":{"alias_symbol":[],"prev_symbol":["C11orf85"]},"alphafold":{"accession":"Q3KP22","domains":[{"cath_id":"-","chopping":"1-31_38-51","consensus_level":"medium","plddt":81.6471,"start":1,"end":51}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q3KP22","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q3KP22-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q3KP22-F1-predicted_aligned_error_v6.png","plddt_mean":60.88},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MAJIN","jax_strain_url":"https://www.jax.org/strain/search?query=MAJIN"},"sequence":{"accession":"Q3KP22","fasta_url":"https://rest.uniprot.org/uniprotkb/Q3KP22.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q3KP22/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q3KP22"}},"corpus_meta":[{"pmid":"26548954","id":"PMC_26548954","title":"MAJIN Links Telomeric DNA to the Nuclear Membrane by Exchanging Telomere Cap.","date":"2015","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/26548954","citation_count":126,"is_preprint":false},{"pmid":"30718482","id":"PMC_30718482","title":"The meiotic TERB1-TERB2-MAJIN complex tethers telomeres to the nuclear envelope.","date":"2019","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/30718482","citation_count":41,"is_preprint":false},{"pmid":"33211200","id":"PMC_33211200","title":"Disruption of human meiotic telomere complex genes TERB1, TERB2 and MAJIN in men with non-obstructive azoospermia.","date":"2020","source":"Human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/33211200","citation_count":37,"is_preprint":false},{"pmid":"30559341","id":"PMC_30559341","title":"Structural basis of meiotic telomere attachment to the nuclear envelope by MAJIN-TERB2-TERB1.","date":"2018","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/30559341","citation_count":33,"is_preprint":false},{"pmid":"29141207","id":"PMC_29141207","title":"Distinct TERB1 Domains Regulate Different Protein Interactions in Meiotic Telomere Movement.","date":"2017","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/29141207","citation_count":30,"is_preprint":false},{"pmid":"34326397","id":"PMC_34326397","title":"CRISPR/Cas9-based genetic screen of SCNT-reprogramming resistant genes identifies critical genes for male germ cell development in mice.","date":"2021","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/34326397","citation_count":19,"is_preprint":false},{"pmid":"32408858","id":"PMC_32408858","title":"The TERB1-TERB2-MAJIN complex of mouse meiotic telomeres dates back to the common ancestor of metazoans.","date":"2020","source":"BMC evolutionary biology","url":"https://pubmed.ncbi.nlm.nih.gov/32408858","citation_count":17,"is_preprint":false},{"pmid":"33015044","id":"PMC_33015044","title":"Tethering of Telomeres to the Nuclear Envelope Is Mediated by SUN1-MAJIN and Possibly Promoted by SPDYA-CDK2 During Meiosis.","date":"2020","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/33015044","citation_count":15,"is_preprint":false},{"pmid":"35081355","id":"PMC_35081355","title":"The TERB1 MYB domain suppresses telomere erosion in meiotic prophase I.","date":"2022","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/35081355","citation_count":10,"is_preprint":false},{"pmid":"36753547","id":"PMC_36753547","title":"MJL-1 is a nuclear envelope protein required for homologous chromosome pairing and regulation of synapsis during meiosis in C. elegans.","date":"2023","source":"Science advances","url":"https://pubmed.ncbi.nlm.nih.gov/36753547","citation_count":10,"is_preprint":false},{"pmid":"35342767","id":"PMC_35342767","title":"Computational Analysis of the Potential Impact of MTC Complex Missenses SNPs Associated with Male Infertility.","date":"2022","source":"BioMed research international","url":"https://pubmed.ncbi.nlm.nih.gov/35342767","citation_count":4,"is_preprint":false},{"pmid":"38511802","id":"PMC_38511802","title":"Telomeric function and regulation during male meiosis in mice and humans.","date":"2024","source":"Andrology","url":"https://pubmed.ncbi.nlm.nih.gov/38511802","citation_count":2,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7406,"output_tokens":1878,"usd":0.025194,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8740,"output_tokens":2512,"usd":0.05325,"stage2_stop_reason":"end_turn"},"total_usd":0.078444,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2015,\n      \"finding\": \"MAJIN is a putative transmembrane protein of the inner nuclear membrane (INM) that, together with TERB1 and TERB2, forms a meiotic telomere complex. TERB1/2-MAJIN initially assembles on the INM sequestered by MAJIN. In early meiosis, a chimeric complex of TERB1/2-MAJIN and shelterin is formed; during prophase this matures into DNA-bound TERB1/2-MAJIN by releasing shelterin ('telomere cap exchange'), creating a direct link between telomeric DNA and the INM. These processes are regulated by CDK-dependent phosphorylation and the DNA-binding activity of MAJIN.\",\n      \"method\": \"Co-immunoprecipitation, mouse germ-cell genetics (knockout mice), live-cell and immunofluorescence imaging, biochemical fractionation, functional mutagenesis\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (Co-IP, KO mice, localization, mutagenesis) in a single focused study; independently replicated by subsequent structural studies\",\n      \"pmids\": [\"26548954\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Crystal structure of the MAJIN-TERB2 complex reveals a 2:2 hetero-tetramer that binds strongly to DNA and is tethered through long flexible linkers to the inner nuclear membrane and two TRF1-binding TERB2-TERB1 complexes. Structured illumination microscopy and biochemical studies show that MAJIN-TERB2-TERB1 recruits telomere-bound TRF1, which is then displaced during pachytene, allowing MAJIN-TERB2-TERB1 to bind telomeric DNA directly and form a mature attachment plate.\",\n      \"method\": \"X-ray crystallography, X-ray scattering, structured illumination microscopy, in vitro DNA-binding assays\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus orthogonal biophysical and microscopy methods; consistent with and extends findings of PMID:26548954\",\n      \"pmids\": [\"30559341\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Crystal structures of human TERB1-TERB2 and TERB2-MAJIN subcomplexes were determined. Specific disruption of the TERB2-MAJIN interaction in mouse Terb2 knock-in mice abolishes telomere attachment to the nuclear envelope and causes aberrant homologous pairing and disordered synapsis, establishing that direct TERB2-MAJIN protein-protein interaction is required for meiotic telomere-NE tethering.\",\n      \"method\": \"X-ray crystallography, knock-in mouse genetics with point mutations disrupting TERB2-MAJIN interface, immunofluorescence for telomere attachment and synapsis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure combined with in vivo genetic disruption and defined cellular phenotype; independent study replicating the complex requirement\",\n      \"pmids\": [\"30718482\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"TRF1 directs the assembly of TERB1-TERB2-MAJIN on telomeres in vivo; germ-cell-specific TRF1 knockout eliminates TERB1-TERB2-MAJIN telomere localization. TERB2 and MAJIN do not mediate cohesin recruitment at telomeres; that function is confined to the MYB-like domain of TERB1.\",\n      \"method\": \"Germ-cell-specific TRF1 conditional knockout mice, co-immunoprecipitation, immunofluorescence\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean conditional KO with defined assembly phenotype plus Co-IP domain mapping; two orthogonal approaches\",\n      \"pmids\": [\"29141207\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"SUN1 interacts directly with MAJIN (and with TERB1) at the nuclear envelope; the SUN1-MAJIN interaction is stronger than the SUN1-TERB1 interaction. Both MAJIN and the CDK2-activator SPDYA bind to the N-terminal domain of SUN1 at overlapping sites. CDK2 inhibition decreases the SUN1-MAJIN interaction, suggesting CDK2-dependent phosphorylation promotes telomere-NE attachment via SUN1-MAJIN.\",\n      \"method\": \"Co-immunoprecipitation, GST pulldown, binding-site mapping with truncation constructs, CDK2 inhibitor treatment\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — Co-IP and pulldown mapping in a single lab, supported by inhibitor data but no structural validation or in vivo genetic confirmation of the SUN1-MAJIN interface\",\n      \"pmids\": [\"33015044\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The TERB1 MYB domain does not mediate telomere localization of the downstream TERB2-MAJIN complex; Terb1 point-mutant mice lacking MYB DNA-binding activity show normal TERB2-MAJIN telomere localization. Instead, the MYB domain regulates cohesin enrichment and axial element remodeling at telomeres in the early-to-late pachytene transition, suppressing telomere erosion.\",\n      \"method\": \"Terb1 point-mutant knock-in mice, immunofluorescence for TERB2/MAJIN localization, cohesin and synaptonemal complex markers, telomere length analysis\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean knock-in genetics with defined phenotypic readouts for MAJIN localization; single lab, single study\",\n      \"pmids\": [\"35081355\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MAJIN is a meiosis-specific inner nuclear membrane protein that anchors telomeres to the nuclear envelope by forming a 2:2 hetero-tetrameric complex with TERB2, whose structure is established by crystallography; this MAJIN-TERB2 core is linked via long flexible linkers to TERB1 (which binds TRF1) and to SUN1 at the NE, and the entire TERB1-TERB2-MAJIN (TTM) complex undergoes a CDK-regulated 'telomere cap exchange'—first co-assembling with shelterin/TRF1 at the INM then displacing shelterin to bind telomeric DNA directly—thereby transmitting cytoskeletal forces through the LINC complex to drive chromosome movements required for homolog pairing and recombination.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MAJIN is a meiosis-specific inner nuclear membrane protein that physically tethers telomeres to the nuclear envelope to enable the chromosome movements underlying homolog pairing and recombination [#0]. As a putative transmembrane component of the inner nuclear membrane, MAJIN nucleates assembly of the meiotic telomere complex by sequestering TERB1 and TERB2 at the membrane, where the complex first forms a chimeric assembly with shelterin and then matures into a DNA-bound state by releasing shelterin in a CDK-phosphorylation-regulated 'telomere cap exchange' [#0]. Structurally, MAJIN and TERB2 form a 2:2 hetero-tetramer that binds DNA directly and is joined through long flexible linkers to TERB1, which engages telomere-bound TRF1; TRF1 is displaced during pachytene to allow the MAJIN-TERB2-TERB1 module to grip telomeric DNA and form a mature attachment plate [#1]. The direct TERB2-MAJIN protein-protein interaction is essential in vivo: disrupting this interface in mice abolishes telomere-nuclear envelope tethering and produces aberrant homolog pairing and disordered synapsis [#2]. Telomeric recruitment of the complex is directed by TRF1, since germ-cell TRF1 loss eliminates TERB1-TERB2-MAJIN telomere localization [#3], and MAJIN connects this module to the LINC complex by binding directly to SUN1 at the nuclear envelope in a CDK2-promoted manner [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2015,\n      \"claim\": \"Established MAJIN as a meiosis-specific INM protein and defined the core logic of meiotic telomere attachment, answering how telomeres become physically coupled to the nuclear envelope.\",\n      \"evidence\": \"Co-IP, knockout mouse germ-cell genetics, imaging, fractionation, and functional mutagenesis in mouse\",\n      \"pmids\": [\"26548954\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic basis of the MAJIN-TERB2 interaction not resolved\", \"Molecular trigger and ordering of the shelterin-to-DNA cap exchange not fully defined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Showed that TRF1 directs telomeric assembly of the TERB1-TERB2-MAJIN complex and separated MAJIN/TERB2 from the cohesin-recruiting function, clarifying the division of labor within the complex.\",\n      \"evidence\": \"Germ-cell-specific TRF1 conditional knockout mice, Co-IP, and immunofluorescence\",\n      \"pmids\": [\"29141207\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How TRF1 recruitment is handed off during cap exchange not mechanistically detailed\", \"Does not address MAJIN membrane topology\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Resolved the 2:2 MAJIN-TERB2 hetero-tetramer and its DNA-binding capacity, explaining structurally how the complex tethers via flexible linkers and grips telomeric DNA after TRF1 displacement.\",\n      \"evidence\": \"X-ray crystallography, X-ray scattering, structured illumination microscopy, and in vitro DNA-binding assays\",\n      \"pmids\": [\"30559341\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structure of full-length membrane-embedded MAJIN not determined\", \"Conformational changes during cap exchange not captured\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Demonstrated that the direct TERB2-MAJIN interface is genetically required for telomere-NE tethering and proper synapsis, converting the structural model into an in vivo functional requirement.\",\n      \"evidence\": \"Crystal structures of human TERB1-TERB2 and TERB2-MAJIN subcomplexes plus interface-disrupting knock-in mouse genetics with synapsis readouts\",\n      \"pmids\": [\"30718482\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative contribution of MAJIN DNA-binding versus TERB2 binding to attachment strength not separated\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Identified a direct MAJIN-SUN1 interaction at the nuclear envelope and its CDK2 dependence, providing the molecular link between the telomere complex and the LINC complex.\",\n      \"evidence\": \"Co-IP, GST pulldown, truncation-based binding-site mapping, and CDK2 inhibitor treatment\",\n      \"pmids\": [\"33015044\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural validation of the SUN1-MAJIN interface\", \"No in vivo genetic confirmation of the interaction's functional requirement\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Distinguished the TERB1 MYB domain's role from MAJIN/TERB2 localization, showing that MYB DNA-binding is dispensable for TERB2-MAJIN telomere recruitment and instead controls cohesin and axial element remodeling.\",\n      \"evidence\": \"Terb1 MYB point-mutant knock-in mice with MAJIN/TERB2 localization, cohesin, synaptonemal, and telomere-length readouts\",\n      \"pmids\": [\"35081355\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab, single study\", \"Does not define what within the complex independently anchors TERB2-MAJIN to telomeres after TRF1 handoff\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The precise molecular trigger that drives the shelterin-to-direct-DNA cap exchange and the force-transmission dynamics from SUN1/LINC through MAJIN to moving telomeres remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Real-time mechanics of cap exchange not visualized\", \"In vivo necessity of the SUN1-MAJIN interface not genetically tested\", \"Membrane topology of MAJIN not structurally confirmed\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0003677\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 2, 4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005635\", \"supporting_discovery_ids\": [0, 1, 2, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"complexes\": [\n      \"TERB1-TERB2-MAJIN (TTM) complex\",\n      \"LINC complex (via SUN1)\"\n    ],\n    \"partners\": [\n      \"TERB2\",\n      \"TERB1\",\n      \"TRF1\",\n      \"SUN1\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}