{"gene":"KLRC3","run_date":"2026-04-28T18:30:27","timeline":{"discoveries":[{"year":1998,"finding":"NKG2-C (KLRC3 product, Kp39) covalently associates with CD94 to form an activating receptor complex on a subset of human NK cells lacking NKG2-A expression. Biochemical analysis of COS7 cells co-transfected with CD94 and NKG2-C confirmed the identity of Kp39 as NKG2-C, and cross-linking with a novel NKG2-specific mAb (P25) triggered cytolytic activity in redirected killing assays.","method":"Immunoprecipitation, peptide mapping, co-transfection in COS7 cells, redirected killing assay, RT-PCR on NK clones","journal":"European journal of immunology","confidence":"High","confidence_rationale":"Tier 1-2 — reconstitution in transfected cells plus multiple orthogonal biochemical and functional methods in a single study","pmids":["9485212"],"is_preprint":false},{"year":1997,"finding":"NKG2-F (KLRC4), a new NKG2 family member, was cloned and found to lack a lectin domain despite sharing a conserved 24-amino acid sequence with other NKG2 members including NKG2-E (KLRC3), suggesting it can still form heterodimers with CD94. This work also established the genomic relationship between NKG2-E (KLRC3) and other family members.","method":"Molecular cloning, sequence analysis, genomic localization","journal":"European journal of immunology","confidence":"Low","confidence_rationale":"Tier 4 — computational/sequence prediction of heterodimer capacity; no direct functional validation of KLRC3 itself","pmids":["9394807"],"is_preprint":false},{"year":1998,"finding":"The KLRC (NKG2) gene cluster, including KLRC3/NKG2-E, was mapped to human chromosome 12p12.3-p13.2 within the natural killer gene complex, with gene order established as NKG2-C/NKG2-A / NKG2-E / NKG2-F / NKG2-D / CD94.","method":"Sequence analysis of a 62-kb genomic region, physical mapping","journal":"Genomics","confidence":"Medium","confidence_rationale":"Tier 2 — direct genomic sequencing and mapping; establishes chromosomal organization but limited functional mechanistic data for KLRC3 specifically","pmids":["9598306"],"is_preprint":false},{"year":2002,"finding":"KLRC3/NKG2-E transcript is expressed in NK cell clones; quantitative RT-PCR showed that NKG2-E and NKG2-H are co-generated as splice variants at a constant ratio, and NKG2-E transcript levels correlated with surface receptor expression measured by flow cytometry and with NK cell cytotoxicity in redirected ADCC assays.","method":"Quantitative real-time RT-PCR, flow cytometry, redirected ADCC cytotoxicity assay on NK cell clones","journal":"Journal of immunological methods","confidence":"Medium","confidence_rationale":"Tier 2-3 — direct expression-function correlation in clonal NK cells with two orthogonal methods; single lab","pmids":["12191515"],"is_preprint":false},{"year":2004,"finding":"NKG2-E (KLRC3) is constitutively expressed in CD94-depleted resting peripheral CD4+ T cells, in contrast to NKG2-A and NKG2-C which require chronic activation and CD94 upregulation. Occupancy of CD94/NKG2-A (inhibitory) on superantigen-stimulated CD4+ T cells abrogated TNF-α and IFN-γ production, whereas NKG2-C (activating) enhanced production of these cytokines, placing NKG2-E/KLRC3 in a distinct constitutive expression program in CD4+ cells.","method":"RT-PCR on purified human CD4+ and CD8+ T cells, flow cytometry, cytokine measurement after mAb-mediated receptor occupancy","journal":"Immunology and cell biology","confidence":"Medium","confidence_rationale":"Tier 2-3 — direct gene expression experiments with functional cytokine readout; single lab with multiple methods","pmids":["15550116"],"is_preprint":false},{"year":2016,"finding":"KLRC3 silencing in U87-MG glioblastoma cells decreased self-renewal capacity, invasion, proliferation, radioresistance, and tumourigenicity, demonstrating a functional role for KLRC3 in glioblastoma cancer stem cell aggressiveness beyond its known NK cell receptor function.","method":"siRNA knockdown of KLRC3 in glioblastoma cell line, proliferation assay, invasion assay, sphere formation assay, in vivo tumourigenicity","journal":"Journal of cellular and molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 — loss-of-function with multiple defined cellular phenotypic readouts; single lab","pmids":["27641066"],"is_preprint":false},{"year":2018,"finding":"ADSL-produced fumarate upregulates KLRC3 expression in endometrial cancer cells, and KLRC3 knockdown phenocopies ADSL knockdown (decreased proliferation, migration, and invasion), placing KLRC3 downstream of ADSL/fumarate in a pathway that promotes endometrial cancer aggressiveness.","method":"siRNA knockdown of ADSL and KLRC3, fumarate rescue experiment, DNA microarray, quantitative RT-PCR, proliferation and invasion assays","journal":"Laboratory investigation","confidence":"Medium","confidence_rationale":"Tier 2 — epistasis established by knockdown + metabolite rescue with multiple phenotypic readouts; single lab","pmids":["29467457"],"is_preprint":false}],"current_model":"KLRC3 encodes NKG2-E, a type II transmembrane C-type lectin that covalently associates with CD94 to form an activating receptor complex on NK cells and subsets of T cells; it is constitutively expressed in resting CD4+ T cells and induced by chronic stimulation in CD8+ T cells, and beyond its immune receptor role, KLRC3 expression is regulated by ADSL-derived fumarate and promotes cancer cell invasion, proliferation, and radioresistance in glioblastoma and endometrial cancer contexts."},"narrative":{"teleology":[{"year":1997,"claim":"Genomic characterization of the NKG2 family established KLRC3/NKG2-E as a distinct family member with a conserved CD94-interacting motif, predicting its capacity to form heterodimers.","evidence":"Molecular cloning and sequence analysis of NKG2 family genes","pmids":["9394807"],"confidence":"Low","gaps":["No direct biochemical or functional validation of NKG2-E heterodimer formation was performed","Expression pattern of KLRC3 was not characterized","Signaling capacity of NKG2-E was not tested"]},{"year":1998,"claim":"Biochemical reconstitution demonstrated that NKG2-C (closely related to NKG2-E) covalently associates with CD94 to form an activating receptor, and the KLRC gene cluster including KLRC3 was physically mapped to chromosome 12p12.3-p13.2 within the NK gene complex.","evidence":"Co-transfection in COS7 cells, immunoprecipitation, peptide mapping, redirected killing assays; genomic sequencing of 62-kb region","pmids":["9485212","9598306"],"confidence":"High","gaps":["NKG2-E itself was not directly reconstituted as a CD94 partner in this study","Ligand specificity of a putative CD94/NKG2-E complex was unknown","Signaling adaptor usage by NKG2-E was not determined"]},{"year":2002,"claim":"Quantitative expression analysis linked NKG2-E transcript levels to surface receptor expression and NK cell cytotoxicity, establishing NKG2-E as functionally relevant in NK clones and revealing a fixed splicing ratio with NKG2-H.","evidence":"Quantitative real-time RT-PCR, flow cytometry, and redirected ADCC on NK cell clones","pmids":["12191515"],"confidence":"Medium","gaps":["Whether NKG2-E protein itself contributes to cytotoxicity or merely marks receptor-expressing cells was not resolved","NKG2-E surface protein was not directly detected with a specific antibody","Mechanism controlling the fixed NKG2-E/NKG2-H splice ratio was unexplored"]},{"year":2004,"claim":"NKG2-E was found to be constitutively expressed in resting CD4+ T cells independent of CD94, distinguishing its regulation from the activation-dependent NKG2-A and NKG2-C programs and implying a distinct role in adaptive immunity.","evidence":"RT-PCR on purified human CD4+ and CD8+ T cells, flow cytometry, cytokine measurement after receptor occupancy","pmids":["15550116"],"confidence":"Medium","gaps":["Functional consequence of constitutive NKG2-E expression in CD4+ T cells was not directly tested","Whether NKG2-E pairs with an alternative partner in the absence of CD94 was unresolved","Transcriptional regulation driving constitutive NKG2-E expression was not identified"]},{"year":2016,"claim":"Loss-of-function experiments revealed a non-immune role for KLRC3 in glioblastoma, where its silencing reduced cancer stem cell self-renewal, invasion, proliferation, radioresistance, and in vivo tumourigenicity.","evidence":"siRNA knockdown in U87-MG glioblastoma cells with sphere formation, invasion, proliferation, and xenograft assays","pmids":["27641066"],"confidence":"Medium","gaps":["Downstream signaling pathway mediating KLRC3's pro-tumorigenic effects was not identified","Whether KLRC3 acts as a receptor or through a receptor-independent mechanism in cancer cells was unknown","Single cell line used; generalizability across glioblastoma models not established"]},{"year":2018,"claim":"Epistasis experiments placed KLRC3 downstream of ADSL-derived fumarate in endometrial cancer, showing that fumarate upregulates KLRC3 to promote proliferation, migration, and invasion.","evidence":"siRNA knockdown of ADSL and KLRC3 with fumarate rescue, DNA microarray, RT-PCR, proliferation and invasion assays in endometrial cancer cells","pmids":["29467457"],"confidence":"Medium","gaps":["Mechanism by which fumarate regulates KLRC3 transcription (e.g., epigenetic modification, transcription factor activation) was not determined","Whether KLRC3's cancer-promoting function operates through its extracellular lectin domain or intracellular signaling was unclear","In vivo validation of the ADSL–fumarate–KLRC3 axis in endometrial cancer was not performed"]},{"year":null,"claim":"The ligand specificity of a CD94/NKG2-E complex, the signaling adaptor it engages, the mechanism by which KLRC3 promotes cancer aggressiveness, and the transcriptional basis for its constitutive expression in CD4+ T cells all remain unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No HLA-E or other ligand binding data exist specifically for CD94/NKG2-E","Signaling adaptor (e.g., DAP12 vs DAP10) usage by NKG2-E has not been demonstrated","Structural basis for NKG2-E function is absent"]}],"mechanism_profile":{"molecular_activity":[],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,3]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[0,3,4]}],"complexes":["CD94/NKG2-E"],"partners":["CD94"],"other_free_text":[]},"mechanistic_narrative":"KLRC3 encodes NKG2-E, a type II transmembrane C-type lectin-like receptor that covalently heterodimerizes with CD94 to form an activating receptor complex on NK cells and T cell subsets [PMID:9485212]. NKG2-E transcript is constitutively expressed in resting CD4+ T cells independently of CD94, distinguishing it from the activation-dependent expression of NKG2-A and NKG2-C, and NKG2-E/NKG2-H splice variants are co-generated at a fixed ratio in NK cell clones where their levels correlate with surface receptor expression and cytotoxicity [PMID:15550116, PMID:12191515]. Beyond immune receptor function, KLRC3 promotes glioblastoma cancer stem cell self-renewal, invasion, proliferation, and radioresistance, and in endometrial cancer it acts downstream of ADSL-derived fumarate to drive proliferation and migration [PMID:27641066, PMID:29467457]."},"prefetch_data":{"uniprot":{"accession":"Q07444","full_name":"NKG2-E type II integral membrane protein","aliases":["NK cell receptor E","NKG2-E-activating NK receptor"],"length_aa":240,"mass_kda":27.1,"function":"Plays a role as a receptor for the recognition of MHC class I HLA-E molecules by NK cells and some cytotoxic T-cells","subcellular_location":"Membrane","url":"https://www.uniprot.org/uniprotkb/Q07444/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/KLRC3","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/KLRC3","total_profiled":1310},"omim":[{"mim_id":"602894","title":"KILLER CELL LECTIN-LIKE RECEPTOR, SUBFAMILY D, MEMBER 1; KLRD1","url":"https://www.omim.org/entry/602894"},{"mim_id":"602892","title":"KILLER CELL LECTIN-LIKE RECEPTOR, SUBFAMILY C, MEMBER 3; KLRC3","url":"https://www.omim.org/entry/602892"},{"mim_id":"161555","title":"KILLER CELL LECTIN-LIKE RECEPTOR, SUBFAMILY C, MEMBER 1; KLRC1","url":"https://www.omim.org/entry/161555"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Vesicles","reliability":"Uncertain"}],"tissue_specificity":"Group enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"bone marrow","ntpm":1.8},{"tissue":"brain","ntpm":4.7},{"tissue":"intestine","ntpm":1.2},{"tissue":"lymphoid tissue","ntpm":3.9}],"url":"https://www.proteinatlas.org/search/KLRC3"},"hgnc":{"alias_symbol":["NKG2-E"],"prev_symbol":[]},"alphafold":{"accession":"Q07444","domains":[{"cath_id":"3.10.100.10","chopping":"122-238","consensus_level":"high","plddt":87.0863,"start":122,"end":238}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q07444","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q07444-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q07444-F1-predicted_aligned_error_v6.png","plddt_mean":71.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=KLRC3","jax_strain_url":"https://www.jax.org/strain/search?query=KLRC3"},"sequence":{"accession":"Q07444","fasta_url":"https://rest.uniprot.org/uniprotkb/Q07444.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q07444/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q07444"}},"corpus_meta":[{"pmid":"23633568","id":"PMC_23633568","title":"Targeted resequencing implicates the familial Mediterranean fever gene MEFV and the toll-like receptor 4 gene TLR4 in Behçet disease.","date":"2013","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/23633568","citation_count":121,"is_preprint":false},{"pmid":"9485212","id":"PMC_9485212","title":"The activating form of CD94 receptor complex: CD94 covalently associates with the Kp39 protein that represents the product of the NKG2-C gene.","date":"1998","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/9485212","citation_count":93,"is_preprint":false},{"pmid":"18294159","id":"PMC_18294159","title":"The transcriptome of human cytotoxic T cells: similarities and disparities among allostimulated CD4(+) CTL, CD8(+) CTL and NK cells.","date":"2008","source":"American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons","url":"https://pubmed.ncbi.nlm.nih.gov/18294159","citation_count":88,"is_preprint":false},{"pmid":"9394807","id":"PMC_9394807","title":"Cloning of NKG2-F, a new member of the NKG2 family of human natural killer cell receptor genes.","date":"1997","source":"European journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/9394807","citation_count":49,"is_preprint":false},{"pmid":"16112753","id":"PMC_16112753","title":"Microarray and real-time RT-PCR analyses of a novel set of differentially expressed human genes in ECV304 endothelial-like cells infected with dengue virus type 2.","date":"2005","source":"Journal of virological methods","url":"https://pubmed.ncbi.nlm.nih.gov/16112753","citation_count":45,"is_preprint":false},{"pmid":"9598306","id":"PMC_9598306","title":"Sequence analysis of a 62-kb region overlapping the human KLRC cluster of genes.","date":"1998","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/9598306","citation_count":35,"is_preprint":false},{"pmid":"10783260","id":"PMC_10783260","title":"A sequence-ready physical map of the region containing the human natural killer gene complex on chromosome 12p12.3-p13.2.","date":"2000","source":"Genomics","url":"https://pubmed.ncbi.nlm.nih.gov/10783260","citation_count":33,"is_preprint":false},{"pmid":"12191515","id":"PMC_12191515","title":"Differential expression of inhibitory and activating CD94/NKG2 receptors on NK cell clones.","date":"2002","source":"Journal of immunological methods","url":"https://pubmed.ncbi.nlm.nih.gov/12191515","citation_count":31,"is_preprint":false},{"pmid":"29467457","id":"PMC_29467457","title":"Adenylosuccinate lyase enhances aggressiveness of endometrial cancer by increasing killer cell lectin-like receptor C3 expression by fumarate.","date":"2018","source":"Laboratory investigation; 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Biochemical analysis of COS7 cells co-transfected with CD94 and NKG2-C confirmed the identity of Kp39 as NKG2-C, and cross-linking with a novel NKG2-specific mAb (P25) triggered cytolytic activity in redirected killing assays.\",\n      \"method\": \"Immunoprecipitation, peptide mapping, co-transfection in COS7 cells, redirected killing assay, RT-PCR on NK clones\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — reconstitution in transfected cells plus multiple orthogonal biochemical and functional methods in a single study\",\n      \"pmids\": [\"9485212\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"NKG2-F (KLRC4), a new NKG2 family member, was cloned and found to lack a lectin domain despite sharing a conserved 24-amino acid sequence with other NKG2 members including NKG2-E (KLRC3), suggesting it can still form heterodimers with CD94. This work also established the genomic relationship between NKG2-E (KLRC3) and other family members.\",\n      \"method\": \"Molecular cloning, sequence analysis, genomic localization\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 — computational/sequence prediction of heterodimer capacity; no direct functional validation of KLRC3 itself\",\n      \"pmids\": [\"9394807\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"The KLRC (NKG2) gene cluster, including KLRC3/NKG2-E, was mapped to human chromosome 12p12.3-p13.2 within the natural killer gene complex, with gene order established as NKG2-C/NKG2-A / NKG2-E / NKG2-F / NKG2-D / CD94.\",\n      \"method\": \"Sequence analysis of a 62-kb genomic region, physical mapping\",\n      \"journal\": \"Genomics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct genomic sequencing and mapping; establishes chromosomal organization but limited functional mechanistic data for KLRC3 specifically\",\n      \"pmids\": [\"9598306\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"KLRC3/NKG2-E transcript is expressed in NK cell clones; quantitative RT-PCR showed that NKG2-E and NKG2-H are co-generated as splice variants at a constant ratio, and NKG2-E transcript levels correlated with surface receptor expression measured by flow cytometry and with NK cell cytotoxicity in redirected ADCC assays.\",\n      \"method\": \"Quantitative real-time RT-PCR, flow cytometry, redirected ADCC cytotoxicity assay on NK cell clones\",\n      \"journal\": \"Journal of immunological methods\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — direct expression-function correlation in clonal NK cells with two orthogonal methods; single lab\",\n      \"pmids\": [\"12191515\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"NKG2-E (KLRC3) is constitutively expressed in CD94-depleted resting peripheral CD4+ T cells, in contrast to NKG2-A and NKG2-C which require chronic activation and CD94 upregulation. Occupancy of CD94/NKG2-A (inhibitory) on superantigen-stimulated CD4+ T cells abrogated TNF-α and IFN-γ production, whereas NKG2-C (activating) enhanced production of these cytokines, placing NKG2-E/KLRC3 in a distinct constitutive expression program in CD4+ cells.\",\n      \"method\": \"RT-PCR on purified human CD4+ and CD8+ T cells, flow cytometry, cytokine measurement after mAb-mediated receptor occupancy\",\n      \"journal\": \"Immunology and cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — direct gene expression experiments with functional cytokine readout; single lab with multiple methods\",\n      \"pmids\": [\"15550116\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"KLRC3 silencing in U87-MG glioblastoma cells decreased self-renewal capacity, invasion, proliferation, radioresistance, and tumourigenicity, demonstrating a functional role for KLRC3 in glioblastoma cancer stem cell aggressiveness beyond its known NK cell receptor function.\",\n      \"method\": \"siRNA knockdown of KLRC3 in glioblastoma cell line, proliferation assay, invasion assay, sphere formation assay, in vivo tumourigenicity\",\n      \"journal\": \"Journal of cellular and molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — loss-of-function with multiple defined cellular phenotypic readouts; single lab\",\n      \"pmids\": [\"27641066\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"ADSL-produced fumarate upregulates KLRC3 expression in endometrial cancer cells, and KLRC3 knockdown phenocopies ADSL knockdown (decreased proliferation, migration, and invasion), placing KLRC3 downstream of ADSL/fumarate in a pathway that promotes endometrial cancer aggressiveness.\",\n      \"method\": \"siRNA knockdown of ADSL and KLRC3, fumarate rescue experiment, DNA microarray, quantitative RT-PCR, proliferation and invasion assays\",\n      \"journal\": \"Laboratory investigation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — epistasis established by knockdown + metabolite rescue with multiple phenotypic readouts; single lab\",\n      \"pmids\": [\"29467457\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"KLRC3 encodes NKG2-E, a type II transmembrane C-type lectin that covalently associates with CD94 to form an activating receptor complex on NK cells and subsets of T cells; it is constitutively expressed in resting CD4+ T cells and induced by chronic stimulation in CD8+ T cells, and beyond its immune receptor role, KLRC3 expression is regulated by ADSL-derived fumarate and promotes cancer cell invasion, proliferation, and radioresistance in glioblastoma and endometrial cancer contexts.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"KLRC3 encodes NKG2-E, a type II transmembrane C-type lectin-like receptor that covalently heterodimerizes with CD94 to form an activating receptor complex on NK cells and T cell subsets [PMID:9485212]. NKG2-E transcript is constitutively expressed in resting CD4+ T cells independently of CD94, distinguishing it from the activation-dependent expression of NKG2-A and NKG2-C, and NKG2-E/NKG2-H splice variants are co-generated at a fixed ratio in NK cell clones where their levels correlate with surface receptor expression and cytotoxicity [PMID:15550116, PMID:12191515]. Beyond immune receptor function, KLRC3 promotes glioblastoma cancer stem cell self-renewal, invasion, proliferation, and radioresistance, and in endometrial cancer it acts downstream of ADSL-derived fumarate to drive proliferation and migration [PMID:27641066, PMID:29467457].\",\n  \"teleology\": [\n    {\n      \"year\": 1997,\n      \"claim\": \"Genomic characterization of the NKG2 family established KLRC3/NKG2-E as a distinct family member with a conserved CD94-interacting motif, predicting its capacity to form heterodimers.\",\n      \"evidence\": \"Molecular cloning and sequence analysis of NKG2 family genes\",\n      \"pmids\": [\"9394807\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No direct biochemical or functional validation of NKG2-E heterodimer formation was performed\",\n        \"Expression pattern of KLRC3 was not characterized\",\n        \"Signaling capacity of NKG2-E was not tested\"\n      ]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Biochemical reconstitution demonstrated that NKG2-C (closely related to NKG2-E) covalently associates with CD94 to form an activating receptor, and the KLRC gene cluster including KLRC3 was physically mapped to chromosome 12p12.3-p13.2 within the NK gene complex.\",\n      \"evidence\": \"Co-transfection in COS7 cells, immunoprecipitation, peptide mapping, redirected killing assays; genomic sequencing of 62-kb region\",\n      \"pmids\": [\"9485212\", \"9598306\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"NKG2-E itself was not directly reconstituted as a CD94 partner in this study\",\n        \"Ligand specificity of a putative CD94/NKG2-E complex was unknown\",\n        \"Signaling adaptor usage by NKG2-E was not determined\"\n      ]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Quantitative expression analysis linked NKG2-E transcript levels to surface receptor expression and NK cell cytotoxicity, establishing NKG2-E as functionally relevant in NK clones and revealing a fixed splicing ratio with NKG2-H.\",\n      \"evidence\": \"Quantitative real-time RT-PCR, flow cytometry, and redirected ADCC on NK cell clones\",\n      \"pmids\": [\"12191515\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Whether NKG2-E protein itself contributes to cytotoxicity or merely marks receptor-expressing cells was not resolved\",\n        \"NKG2-E surface protein was not directly detected with a specific antibody\",\n        \"Mechanism controlling the fixed NKG2-E/NKG2-H splice ratio was unexplored\"\n      ]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"NKG2-E was found to be constitutively expressed in resting CD4+ T cells independent of CD94, distinguishing its regulation from the activation-dependent NKG2-A and NKG2-C programs and implying a distinct role in adaptive immunity.\",\n      \"evidence\": \"RT-PCR on purified human CD4+ and CD8+ T cells, flow cytometry, cytokine measurement after receptor occupancy\",\n      \"pmids\": [\"15550116\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Functional consequence of constitutive NKG2-E expression in CD4+ T cells was not directly tested\",\n        \"Whether NKG2-E pairs with an alternative partner in the absence of CD94 was unresolved\",\n        \"Transcriptional regulation driving constitutive NKG2-E expression was not identified\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Loss-of-function experiments revealed a non-immune role for KLRC3 in glioblastoma, where its silencing reduced cancer stem cell self-renewal, invasion, proliferation, radioresistance, and in vivo tumourigenicity.\",\n      \"evidence\": \"siRNA knockdown in U87-MG glioblastoma cells with sphere formation, invasion, proliferation, and xenograft assays\",\n      \"pmids\": [\"27641066\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Downstream signaling pathway mediating KLRC3's pro-tumorigenic effects was not identified\",\n        \"Whether KLRC3 acts as a receptor or through a receptor-independent mechanism in cancer cells was unknown\",\n        \"Single cell line used; generalizability across glioblastoma models not established\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Epistasis experiments placed KLRC3 downstream of ADSL-derived fumarate in endometrial cancer, showing that fumarate upregulates KLRC3 to promote proliferation, migration, and invasion.\",\n      \"evidence\": \"siRNA knockdown of ADSL and KLRC3 with fumarate rescue, DNA microarray, RT-PCR, proliferation and invasion assays in endometrial cancer cells\",\n      \"pmids\": [\"29467457\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism by which fumarate regulates KLRC3 transcription (e.g., epigenetic modification, transcription factor activation) was not determined\",\n        \"Whether KLRC3's cancer-promoting function operates through its extracellular lectin domain or intracellular signaling was unclear\",\n        \"In vivo validation of the ADSL–fumarate–KLRC3 axis in endometrial cancer was not performed\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The ligand specificity of a CD94/NKG2-E complex, the signaling adaptor it engages, the mechanism by which KLRC3 promotes cancer aggressiveness, and the transcriptional basis for its constitutive expression in CD4+ T cells all remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No HLA-E or other ligand binding data exist specifically for CD94/NKG2-E\",\n        \"Signaling adaptor (e.g., DAP12 vs DAP10) usage by NKG2-E has not been demonstrated\",\n        \"Structural basis for NKG2-E function is absent\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [0, 3, 4]}\n    ],\n    \"complexes\": [\n      \"CD94/NKG2-E\"\n    ],\n    \"partners\": [\n      \"CD94\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}