{"gene":"NTSR2","run_date":"2026-06-10T05:19:52","timeline":{"discoveries":[{"year":2009,"finding":"Human NTSR2 forms heterodimers with NTSR1; the TM2-TM4 region of NTSR2 constitutes the dimerization interface. Co-expression of NTSR2 suppresses NTSR1-mediated adenylate cyclase/cAMP and phospholipase C activation, and causes intracellular retention of NTSR1, preventing its proper recruitment to the plasma membrane.","method":"Co-immunoprecipitation of differentially epitope-tagged receptors, chimeric receptor constructs, cAMP and PLC functional assays, confocal microscopy","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — reciprocal Co-IP, chimeric domain mapping, and multiple functional readouts in a single lab study","pmids":["19968961"],"is_preprint":false},{"year":2015,"finding":"In C6 glioma cells expressing NTSR2 (and its isoform vNTSR2), internalization of the neurotensin/NTSR2 complex is required for ERK1/2 phosphorylation; pharmacological blockade of internalization with levocabastine (NTSR2 antagonist) completely abolishes NTS-induced ERK1/2 activation.","method":"RT-PCR for receptor expression, pharmacological blockade with levocabastine, ERK1/2 phosphorylation assays, NTS-polyplex gene transfer experiments","journal":"Cellular and molecular neurobiology","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — pharmacological approach with multiple readouts in single lab; mechanism relies on antagonist specificity","pmids":["25772140"],"is_preprint":false},{"year":2004,"finding":"Ntsr2-deficient mice show a significant alteration in jump latency in the hot plate test compared to wild-type or Ntsr1-deficient mice, establishing a specific role for Ntsr2 in thermal nociception, distinct from Ntsr1.","method":"Generation of Ntsr2 knockout mice, hot plate test, tail flick and hind paw licking behavioral assays, in situ hybridization for mRNA distribution","journal":"Brain research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO with defined behavioral phenotype and receptor-subtype comparison, single lab","pmids":["14725975"],"is_preprint":false},{"year":2016,"finding":"In NTSR3/sortilin knockout mice, brain NTSR2 protein levels are 2-fold increased along with elevated neurotensin, and these mice exhibit resistance to thermal and chemical pain, confirming that NTSR3/sortilin interacts with the neurotensinergic system and modulates NTSR2-mediated nociception.","method":"NTSR3 knockout mouse model, quantitative PCR, Western blot, AlphaLisa technology for protein quantification, thermal and chemical pain behavioral assays","journal":"Frontiers in neuroscience","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — KO model with multiple quantification methods and behavioral phenotype, single lab","pmids":["27932946"],"is_preprint":false},{"year":2024,"finding":"NTSR2 physically interacts with TrkB (TRKB) in CLL B-cells, forming an oncogenic complex that activates Src family kinase signaling and anti-apoptotic pathways; a peptide targeting the NTSR2-TRKB binding domain reduces their interaction and induces cytotoxic effects in CLL cells.","method":"Binding domain identification, peptide design targeting the interaction interface, Co-IP/interaction assays, Src family kinase signaling analysis, cell viability assays in vitro (MEC-1 cell line) and ex vivo (30 CLL patients)","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — protein interaction identified, peptide disruption used as functional probe, multiple cell systems tested, single lab","pmids":["38480783"],"is_preprint":false},{"year":2001,"finding":"The mouse Ntsr2 gene is organized into four exons spanning ~7 kb, contains transcription initiation sites at 286 and 303 bp upstream of ATG, has a TATA-like box, CAAT box, and putative GATA-2/CREB/Oct-2/Ikaros-2 binding elements in its promoter, and alternative splice donor-acceptor sites generate a short mRNA isoform encoding a truncated receptor; the gene maps to chromosome 12 at ~6 cM from the centromere.","method":"Genomic cloning, primer extension analysis, sequence analysis of promoter elements, genetic mapping","journal":"Brain research. Molecular brain research","confidence":"Medium","confidence_rationale":"Tier 2-3 / Moderate — direct experimental determination of gene structure and transcription initiation sites, single lab","pmids":["11687289"],"is_preprint":false}],"current_model":"NTSR2 is a G protein-coupled neurotensin receptor that (1) heterodimerizes with NTSR1 via its TM2-TM4 region to suppress NTSR1 signaling and cause its intracellular retention, (2) mediates neurotensin-induced ERK1/2 activation in glioma cells through an internalization-dependent mechanism, (3) plays a specific role in thermal nociception as demonstrated by Ntsr2-knockout mice, (4) physically interacts with TrkB (TRKB) in CLL B-cells to activate survival signaling, and (5) is functionally regulated by NTSR3/sortilin, which modulates NTSR2 expression and NT-mediated pain signaling."},"narrative":{"mechanistic_narrative":"NTSR2 is a G protein-coupled neurotensin receptor that modulates neurotensinergic signaling and contributes to nociceptive processing [PMID:14725975]. It heterodimerizes with NTSR1 through its TM2-TM4 region, and this interaction suppresses NTSR1-mediated adenylate cyclase/cAMP and phospholipase C signaling while causing intracellular retention of NTSR1, positioning NTSR2 as a negative regulator of NTSR1 surface expression and output [PMID:19968961]. In glioma cells, neurotensin binding drives ERK1/2 phosphorylation through a mechanism that requires internalization of the neurotensin/NTSR2 complex, since blocking internalization with levocabastine abolishes ERK1/2 activation [PMID:25772140]. At the organismal level, Ntsr2-knockout mice show altered thermal nociception distinct from Ntsr1-deficient animals, and NTSR2 function is regulated by NTSR3/sortilin, whose loss elevates brain NTSR2 protein and neurotensin while conferring resistance to thermal and chemical pain [PMID:14725975, PMID:27932946]. Beyond neuronal signaling, NTSR2 physically interacts with TrkB in chronic lymphocytic leukemia B-cells to form an oncogenic complex that activates Src family kinase and anti-apoptotic signaling, an interaction disruptable by a peptide targeting the binding interface [PMID:38480783].","teleology":[{"year":2001,"claim":"Defining the Ntsr2 gene architecture and promoter established the transcriptional and splicing basis for receptor expression, including a truncated isoform.","evidence":"Genomic cloning, primer extension, and promoter sequence analysis in mouse","pmids":["11687289"],"confidence":"Medium","gaps":["Functional consequence of the truncated isoform unresolved","Regulatory elements not tied to specific tissue expression patterns"]},{"year":2004,"claim":"Knockout of Ntsr2 assigned the receptor a specific role in thermal nociception distinct from NTSR1, separating the two subtypes functionally in vivo.","evidence":"Ntsr2 knockout mice with hot plate, tail flick, and hind paw licking assays plus mRNA distribution mapping","pmids":["14725975"],"confidence":"Medium","gaps":["Cellular circuit and downstream signaling mediating the phenotype not defined","Single behavioral paradigm dominated the positive finding"]},{"year":2009,"claim":"Demonstration that NTSR2 heterodimerizes with NTSR1 and suppresses its signaling revealed a mechanism by which NTSR2 negatively regulates a related receptor subtype.","evidence":"Reciprocal Co-IP of epitope-tagged receptors, chimeric domain mapping, cAMP/PLC assays, and confocal microscopy","pmids":["19968961"],"confidence":"Medium","gaps":["Physiological relevance of the heterodimer in vivo not tested","Whether dimerization affects NTSR2's own signaling unknown"]},{"year":2015,"claim":"Linking NTSR2 internalization to ERK1/2 activation in glioma identified an internalization-dependent route for neurotensin-driven mitogenic signaling.","evidence":"Levocabastine pharmacological blockade and ERK1/2 phosphorylation assays in C6 glioma cells","pmids":["25772140"],"confidence":"Medium","gaps":["Reliance on antagonist specificity for mechanistic conclusion","G protein versus arrestin contribution not dissected"]},{"year":2016,"claim":"Showing that NTSR3/sortilin loss elevates NTSR2 and neurotensin and confers pain resistance placed NTSR2 within a regulatory network controlling nociception.","evidence":"NTSR3 knockout mice with qPCR, Western blot, AlphaLisa quantification, and thermal/chemical pain assays","pmids":["27932946"],"confidence":"Medium","gaps":["Direct physical NTSR2-NTSR3 interaction not demonstrated here","Mechanism of NTSR2 protein level regulation unresolved"]},{"year":2024,"claim":"Identifying an NTSR2-TrkB complex in CLL B-cells extended NTSR2 function to oncogenic survival signaling and offered a disruptable interaction interface.","evidence":"Binding domain mapping, interface-targeting peptide, Co-IP, Src family kinase analysis, and viability assays in MEC-1 cells and 30 CLL patient samples","pmids":["38480783"],"confidence":"Medium","gaps":["Whether neurotensin ligand is required for the complex unclear","Structural basis of the binding domain not resolved"]},{"year":null,"claim":"How NTSR2 couples to G proteins versus internalization-dependent pathways across cell types, and whether its heterodimerization and TrkB interactions operate in the same physiological settings, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of NTSR2 or its complexes","Endogenous ligand-dependence of TrkB and NTSR1 interactions undefined","In vivo relevance of dimerization-based NTSR1 suppression untested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[1,2]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,4]}],"complexes":[],"partners":["NTSR1","TRKB","NTSR3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O95665","full_name":"Neurotensin receptor type 2","aliases":["Levocabastine-sensitive neurotensin receptor"],"length_aa":410,"mass_kda":45.4,"function":"Receptor for the tridecapeptide neurotensin. It is associated with G proteins that activate a phosphatidylinositol-calcium second messenger system","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/O95665/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/NTSR2","classification":"Not Classified","n_dependent_lines":4,"n_total_lines":1208,"dependency_fraction":0.0033112582781456954},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/NTSR2","total_profiled":1310},"omim":[{"mim_id":"616328","title":"LONG INTERGENIC NONCODING RNA PINKY","url":"https://www.omim.org/entry/616328"},{"mim_id":"605538","title":"NEUROTENSIN RECEPTOR 2; NTSR2","url":"https://www.omim.org/entry/605538"},{"mim_id":"600693","title":"POLYPYRIMIDINE TRACT-BINDING PROTEIN 1; PTBP1","url":"https://www.omim.org/entry/600693"},{"mim_id":"162651","title":"NEUROTENSIN RECEPTOR 1; NTSR1","url":"https://www.omim.org/entry/162651"},{"mim_id":"162650","title":"NEUROTENSIN; NTS","url":"https://www.omim.org/entry/162650"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"brain","ntpm":108.3}],"url":"https://www.proteinatlas.org/search/NTSR2"},"hgnc":{"alias_symbol":["NTR2"],"prev_symbol":[]},"alphafold":{"accession":"O95665","domains":[{"cath_id":"1.20.1070.10","chopping":"46-180_188-241_291-377","consensus_level":"high","plddt":89.4116,"start":46,"end":377}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O95665","model_url":"https://alphafold.ebi.ac.uk/files/AF-O95665-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O95665-F1-predicted_aligned_error_v6.png","plddt_mean":78.88},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=NTSR2","jax_strain_url":"https://www.jax.org/strain/search?query=NTSR2"},"sequence":{"accession":"O95665","fasta_url":"https://rest.uniprot.org/uniprotkb/O95665.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O95665/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O95665"}},"corpus_meta":[{"pmid":"16357217","id":"PMC_16357217","title":"Spliceosome disassembly catalyzed by Prp43 and its associated components Ntr1 and Ntr2.","date":"2005","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/16357217","citation_count":136,"is_preprint":false},{"pmid":"27812217","id":"PMC_27812217","title":"Activation of Bicyclic Nitro-drugs by a Novel Nitroreductase (NTR2) in Leishmania.","date":"2016","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/27812217","citation_count":72,"is_preprint":false},{"pmid":"17893323","id":"PMC_17893323","title":"Dynamic interactions of Ntr1-Ntr2 with Prp43 and with U5 govern the recruitment of Prp43 to mediate spliceosome disassembly.","date":"2007","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/17893323","citation_count":69,"is_preprint":false},{"pmid":"14725975","id":"PMC_14725975","title":"Comparison of mice deficient in the high- or low-affinity neurotensin receptors, Ntsr1 or Ntsr2, reveals a novel function for Ntsr2 in thermal nociception.","date":"2004","source":"Brain research","url":"https://pubmed.ncbi.nlm.nih.gov/14725975","citation_count":66,"is_preprint":false},{"pmid":"23109725","id":"PMC_23109725","title":"Differential expression of neurotensin and specific receptors, NTSR1 and NTSR2, in normal and malignant human B lymphocytes.","date":"2012","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/23109725","citation_count":36,"is_preprint":false},{"pmid":"19968961","id":"PMC_19968961","title":"Intermolecular cross-talk between NTR1 and NTR2 neurotensin receptor promotes intracellular sequestration and functional inhibition of NTR1 receptors.","date":"2009","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/19968961","citation_count":25,"is_preprint":false},{"pmid":"25772140","id":"PMC_25772140","title":"The Internalization of Neurotensin by the Low-Affinity Neurotensin Receptors (NTSR2 and vNTSR2) Activates ERK 1/2 in Glioma Cells and Allows Neurotensin-Polyplex Transfection of tGAS1.","date":"2015","source":"Cellular and molecular neurobiology","url":"https://pubmed.ncbi.nlm.nih.gov/25772140","citation_count":16,"is_preprint":false},{"pmid":"31219728","id":"PMC_31219728","title":"Identification of proteins associated with splicing factors Ntr1, Ntr2, Brr2 and Gpl1 in the fission yeast Schizosaccharomyces pombe.","date":"2019","source":"Cell cycle (Georgetown, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/31219728","citation_count":12,"is_preprint":false},{"pmid":"29490241","id":"PMC_29490241","title":"Intrinsically Disordered Protein Ntr2 Modulates the Spliceosomal RNA Helicase Brr2.","date":"2018","source":"Biophysical journal","url":"https://pubmed.ncbi.nlm.nih.gov/29490241","citation_count":11,"is_preprint":false},{"pmid":"27932946","id":"PMC_27932946","title":"Increased Brain Neurotensin and NTSR2 Lead to Weak Nociception in NTSR3/Sortilin Knockout Mice.","date":"2016","source":"Frontiers in neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/27932946","citation_count":10,"is_preprint":false},{"pmid":"11687289","id":"PMC_11687289","title":"Mouse neurotensin receptor 2 gene (Ntsr2): genomic organization, transcriptional regulation and genetic mapping on chromosome 12.","date":"2001","source":"Brain research. Molecular brain research","url":"https://pubmed.ncbi.nlm.nih.gov/11687289","citation_count":9,"is_preprint":false},{"pmid":"37962046","id":"PMC_37962046","title":"Physiological and Pathological Roles of NTSR2 in Several Organs and Diseases (Review).","date":"2024","source":"Protein and peptide letters","url":"https://pubmed.ncbi.nlm.nih.gov/37962046","citation_count":2,"is_preprint":false},{"pmid":"38480783","id":"PMC_38480783","title":"Targeting the NTSR2/TrkB oncogenic pathway in chronic lymphocytic leukemia.","date":"2024","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/38480783","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8061,"output_tokens":1616,"usd":0.024212,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8399,"output_tokens":2229,"usd":0.04886,"stage2_stop_reason":"end_turn"},"total_usd":0.073072,"stage1_batch_id":"msgbatch_013a8chtv3AWyTqv4z4sEF4C","stage2_batch_id":"msgbatch_01AHsuW63vinsvuTgzmQ3n62","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2009,\n      \"finding\": \"Human NTSR2 forms heterodimers with NTSR1; the TM2-TM4 region of NTSR2 constitutes the dimerization interface. Co-expression of NTSR2 suppresses NTSR1-mediated adenylate cyclase/cAMP and phospholipase C activation, and causes intracellular retention of NTSR1, preventing its proper recruitment to the plasma membrane.\",\n      \"method\": \"Co-immunoprecipitation of differentially epitope-tagged receptors, chimeric receptor constructs, cAMP and PLC functional assays, confocal microscopy\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — reciprocal Co-IP, chimeric domain mapping, and multiple functional readouts in a single lab study\",\n      \"pmids\": [\"19968961\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"In C6 glioma cells expressing NTSR2 (and its isoform vNTSR2), internalization of the neurotensin/NTSR2 complex is required for ERK1/2 phosphorylation; pharmacological blockade of internalization with levocabastine (NTSR2 antagonist) completely abolishes NTS-induced ERK1/2 activation.\",\n      \"method\": \"RT-PCR for receptor expression, pharmacological blockade with levocabastine, ERK1/2 phosphorylation assays, NTS-polyplex gene transfer experiments\",\n      \"journal\": \"Cellular and molecular neurobiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — pharmacological approach with multiple readouts in single lab; mechanism relies on antagonist specificity\",\n      \"pmids\": [\"25772140\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Ntsr2-deficient mice show a significant alteration in jump latency in the hot plate test compared to wild-type or Ntsr1-deficient mice, establishing a specific role for Ntsr2 in thermal nociception, distinct from Ntsr1.\",\n      \"method\": \"Generation of Ntsr2 knockout mice, hot plate test, tail flick and hind paw licking behavioral assays, in situ hybridization for mRNA distribution\",\n      \"journal\": \"Brain research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with defined behavioral phenotype and receptor-subtype comparison, single lab\",\n      \"pmids\": [\"14725975\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"In NTSR3/sortilin knockout mice, brain NTSR2 protein levels are 2-fold increased along with elevated neurotensin, and these mice exhibit resistance to thermal and chemical pain, confirming that NTSR3/sortilin interacts with the neurotensinergic system and modulates NTSR2-mediated nociception.\",\n      \"method\": \"NTSR3 knockout mouse model, quantitative PCR, Western blot, AlphaLisa technology for protein quantification, thermal and chemical pain behavioral assays\",\n      \"journal\": \"Frontiers in neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — KO model with multiple quantification methods and behavioral phenotype, single lab\",\n      \"pmids\": [\"27932946\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"NTSR2 physically interacts with TrkB (TRKB) in CLL B-cells, forming an oncogenic complex that activates Src family kinase signaling and anti-apoptotic pathways; a peptide targeting the NTSR2-TRKB binding domain reduces their interaction and induces cytotoxic effects in CLL cells.\",\n      \"method\": \"Binding domain identification, peptide design targeting the interaction interface, Co-IP/interaction assays, Src family kinase signaling analysis, cell viability assays in vitro (MEC-1 cell line) and ex vivo (30 CLL patients)\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — protein interaction identified, peptide disruption used as functional probe, multiple cell systems tested, single lab\",\n      \"pmids\": [\"38480783\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"The mouse Ntsr2 gene is organized into four exons spanning ~7 kb, contains transcription initiation sites at 286 and 303 bp upstream of ATG, has a TATA-like box, CAAT box, and putative GATA-2/CREB/Oct-2/Ikaros-2 binding elements in its promoter, and alternative splice donor-acceptor sites generate a short mRNA isoform encoding a truncated receptor; the gene maps to chromosome 12 at ~6 cM from the centromere.\",\n      \"method\": \"Genomic cloning, primer extension analysis, sequence analysis of promoter elements, genetic mapping\",\n      \"journal\": \"Brain research. Molecular brain research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 / Moderate — direct experimental determination of gene structure and transcription initiation sites, single lab\",\n      \"pmids\": [\"11687289\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"NTSR2 is a G protein-coupled neurotensin receptor that (1) heterodimerizes with NTSR1 via its TM2-TM4 region to suppress NTSR1 signaling and cause its intracellular retention, (2) mediates neurotensin-induced ERK1/2 activation in glioma cells through an internalization-dependent mechanism, (3) plays a specific role in thermal nociception as demonstrated by Ntsr2-knockout mice, (4) physically interacts with TrkB (TRKB) in CLL B-cells to activate survival signaling, and (5) is functionally regulated by NTSR3/sortilin, which modulates NTSR2 expression and NT-mediated pain signaling.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"NTSR2 is a G protein-coupled neurotensin receptor that modulates neurotensinergic signaling and contributes to nociceptive processing [#2]. It heterodimerizes with NTSR1 through its TM2-TM4 region, and this interaction suppresses NTSR1-mediated adenylate cyclase/cAMP and phospholipase C signaling while causing intracellular retention of NTSR1, positioning NTSR2 as a negative regulator of NTSR1 surface expression and output [#0]. In glioma cells, neurotensin binding drives ERK1/2 phosphorylation through a mechanism that requires internalization of the neurotensin/NTSR2 complex, since blocking internalization with levocabastine abolishes ERK1/2 activation [#1]. At the organismal level, Ntsr2-knockout mice show altered thermal nociception distinct from Ntsr1-deficient animals, and NTSR2 function is regulated by NTSR3/sortilin, whose loss elevates brain NTSR2 protein and neurotensin while conferring resistance to thermal and chemical pain [#2, #3]. Beyond neuronal signaling, NTSR2 physically interacts with TrkB in chronic lymphocytic leukemia B-cells to form an oncogenic complex that activates Src family kinase and anti-apoptotic signaling, an interaction disruptable by a peptide targeting the binding interface [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2001,\n      \"claim\": \"Defining the Ntsr2 gene architecture and promoter established the transcriptional and splicing basis for receptor expression, including a truncated isoform.\",\n      \"evidence\": \"Genomic cloning, primer extension, and promoter sequence analysis in mouse\",\n      \"pmids\": [\"11687289\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of the truncated isoform unresolved\", \"Regulatory elements not tied to specific tissue expression patterns\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Knockout of Ntsr2 assigned the receptor a specific role in thermal nociception distinct from NTSR1, separating the two subtypes functionally in vivo.\",\n      \"evidence\": \"Ntsr2 knockout mice with hot plate, tail flick, and hind paw licking assays plus mRNA distribution mapping\",\n      \"pmids\": [\"14725975\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cellular circuit and downstream signaling mediating the phenotype not defined\", \"Single behavioral paradigm dominated the positive finding\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Demonstration that NTSR2 heterodimerizes with NTSR1 and suppresses its signaling revealed a mechanism by which NTSR2 negatively regulates a related receptor subtype.\",\n      \"evidence\": \"Reciprocal Co-IP of epitope-tagged receptors, chimeric domain mapping, cAMP/PLC assays, and confocal microscopy\",\n      \"pmids\": [\"19968961\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological relevance of the heterodimer in vivo not tested\", \"Whether dimerization affects NTSR2's own signaling unknown\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Linking NTSR2 internalization to ERK1/2 activation in glioma identified an internalization-dependent route for neurotensin-driven mitogenic signaling.\",\n      \"evidence\": \"Levocabastine pharmacological blockade and ERK1/2 phosphorylation assays in C6 glioma cells\",\n      \"pmids\": [\"25772140\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Reliance on antagonist specificity for mechanistic conclusion\", \"G protein versus arrestin contribution not dissected\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Showing that NTSR3/sortilin loss elevates NTSR2 and neurotensin and confers pain resistance placed NTSR2 within a regulatory network controlling nociception.\",\n      \"evidence\": \"NTSR3 knockout mice with qPCR, Western blot, AlphaLisa quantification, and thermal/chemical pain assays\",\n      \"pmids\": [\"27932946\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct physical NTSR2-NTSR3 interaction not demonstrated here\", \"Mechanism of NTSR2 protein level regulation unresolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identifying an NTSR2-TrkB complex in CLL B-cells extended NTSR2 function to oncogenic survival signaling and offered a disruptable interaction interface.\",\n      \"evidence\": \"Binding domain mapping, interface-targeting peptide, Co-IP, Src family kinase analysis, and viability assays in MEC-1 cells and 30 CLL patient samples\",\n      \"pmids\": [\"38480783\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether neurotensin ligand is required for the complex unclear\", \"Structural basis of the binding domain not resolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How NTSR2 couples to G proteins versus internalization-dependent pathways across cell types, and whether its heterodimerization and TrkB interactions operate in the same physiological settings, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of NTSR2 or its complexes\", \"Endogenous ligand-dependence of TrkB and NTSR1 interactions undefined\", \"In vivo relevance of dimerization-based NTSR1 suppression untested\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 4]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"NTSR1\", \"TRKB\", \"NTSR3\"]\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}