{"gene":"SLITRK3","run_date":"2026-06-10T07:46:35","timeline":{"discoveries":[{"year":2012,"finding":"Slitrk3 acts as a postsynaptic adhesion molecule that selectively induces inhibitory (GABAergic) presynaptic differentiation via trans-synaptic interaction with axonal PTPδ (receptor protein tyrosine phosphatase delta). When expressed in fibroblasts, Slitrk3 triggered only inhibitory presynaptic differentiation in contacting axons of co-cultured hippocampal neurons. Recombinant Slitrk3 preferentially localized to inhibitory postsynaptic sites. Slitrk3-deficient mice showed decreased inhibitory synapse number and function in hippocampal CA1 neurons and increased seizure susceptibility.","method":"Heterologous cell synaptogenesis assay (fibroblast co-culture), recombinant protein localization, Slitrk3 knockout mouse analysis (electrophysiology, immunostaining, EEG), trans-interaction assay with PTPδ","journal":"Nature neuroscience","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — multiple orthogonal methods including heterologous expression assay, knockout mouse phenotyping, and direct binding studies; replicated in subsequent papers","pmids":["22286174"],"is_preprint":false},{"year":2017,"finding":"Slitrk3 (ST3) interacts with Neuroligin 2 (NL2) through their extracellular domains with nanomolar affinity in a cis interaction. During neuronal maturation, both NL2 and ST3 are required together for inhibitory synapse development; selective perturbation of the NL2-ST3 interaction impairs inhibitory synapse development, disrupts hippocampal network activity, and increases seizure susceptibility. NL2 is required for establishing GABAergic transmission in developing neurons, while mature inhibitory synapse development requires both NL2 and ST3 acting synergistically.","method":"Co-immunoprecipitation, binding affinity measurements, hippocampal neuron culture with genetic perturbation, electrophysiology, seizure susceptibility assays","journal":"Neuron","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — binding affinity quantified, reciprocal interaction demonstrated, functional rescue experiments, multiple orthogonal methods in a single rigorous study","pmids":["29107521"],"is_preprint":false},{"year":2019,"finding":"The conserved tyrosine residue Y969 in the intracellular C-terminus of Slitrk3 is critical for GABAergic synapse development. Overexpression of the Y969A mutant markedly reduced gephyrin puncta density and GABAergic transmission in hippocampal neurons. Wild-type ST3, but not ST3 Y969A, rescued GABAergic transmission deficits in neurons lacking endogenous ST3. The C-terminus is not required for ST3 homo-dimerization or trafficking to the cell surface in heterologous cells.","method":"Site-directed mutagenesis, overexpression and rescue experiments in hippocampal neurons, electrophysiology, immunostaining for gephyrin puncta, heterologous cell surface trafficking assay","journal":"Frontiers in molecular neuroscience","confidence":"High","confidence_rationale":"Tier 1 / Moderate — active-site/residue mutagenesis combined with functional rescue and electrophysiology in a single focused study","pmids":["31551708"],"is_preprint":false},{"year":2021,"finding":"ErbB4 interacts in trans with Slitrk3 through the extracellular RLD domain of ErbB4 to promote inhibitory synapse formation onto pyramidal neurons independently of ErbB4 kinase activity. Deletion of the RLD domain abolished induction of gephyrin and GABAAR α1 puncta by ErbB4. Disruption of the ErbB4-Slitrk3 interaction by secretable RLD decreased inhibitory synapses and impaired GABAergic transmission.","method":"Co-immunoprecipitation/pulldown of ErbB4 and Slitrk3, heterologous cell co-culture synaptogenesis assay, domain deletion mutants, kinase-dead knock-in mice, electrophysiology","journal":"Translational psychiatry","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — direct binding demonstrated by co-IP, domain deletion, functional consequence confirmed by electrophysiology in neurons and in vivo knock-in mouse","pmids":["34226493"],"is_preprint":false},{"year":2021,"finding":"Gephyrin interacts with Slitrk3 as part of the synapse stabilization mechanism downstream of adenosine A2A receptor and GABAAR activation. PKA-mediated phosphorylation of gephyrin on serine 303 is required for GABAAR stabilization, and stabilization of pre- and postsynaptic GABAergic elements involves the gephyrin-Slitrk3 interaction.","method":"Co-immunoprecipitation of gephyrin and Slitrk3, phosphorylation site mutagenesis (gephyrin S303), pharmacological receptor activation/inhibition, live imaging of synapse stability","journal":"Science (New York, N.Y.)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — gephyrin-Slitrk3 interaction detected by co-IP; phosphorylation and functional consequence shown in same study, but Slitrk3-specific binding evidence is partially inferred from abstract description","pmids":["34735259"],"is_preprint":false},{"year":2017,"finding":"LAR-RPTP (PTPδ) binding to Slitrk3 (as well as IL1RAPL1 and IL-1RAcP) induces reciprocal higher-order clustering of trans-synaptic adhesion complexes. Crystal structure of LAR-RPTP/IL1RAPL1 complex reveals lateral interactions critical for higher-order assembly; competitive binding of heparan sulfate to LAR-RPTP can dismantle pre-established LAR-RPTP/Slitrk3 trans-synaptic complexes.","method":"Crystal structure determination, cell clustering assay, competitive binding with heparan sulfate, synaptogenesis assay in HEK cell co-culture","journal":"Frontiers in molecular neuroscience","confidence":"Medium","confidence_rationale":"Tier 1–2 / Moderate — crystal structure of related complex, functional clustering assay, but Slitrk3-specific structural data is inferred from the broader LAR-RPTP study","pmids":["29081732"],"is_preprint":false},{"year":2003,"finding":"SLITRK3 protein is characterized as an integral membrane protein with two leucine-rich repeat (LRR) domains similar to Slit proteins and a C-terminal domain partially similar to Trk neurotrophin receptors. It is expressed predominantly in the brain.","method":"Genomic organization analysis, expression profiling (Northern blot/RT-PCR), protein domain characterization","journal":"Gene","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct experimental characterization of protein domain architecture and tissue expression, though functional mechanistic consequence not tested in this paper","pmids":["14557068"],"is_preprint":false},{"year":2024,"finding":"Biallelic loss-of-function variants in SLITRK3 (C566R and E606X) cause epileptic encephalopathy. Patient variants C566R and E606X alter SLITRK3 protein surface expression by causing accumulation in the Golgi apparatus. Primary hippocampal neuron cultures carrying patient variants show reduced GABAergic transmission (confirmed by electrophysiology). SLITRK3 KO mice exhibit spontaneous epileptiform EEG activity, enhanced pentylenetetrazole-induced seizures, increased motor activity, and reduced parvalbumin interneurons.","method":"Patient-derived neuron cultures, electrophysiology, immunostaining of HEK-293 cells (cell surface vs. Golgi localization), SLITRK3 knockout mouse EEG and behavioral analysis","journal":"Frontiers in molecular neuroscience","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — loss-of-function demonstrated by electrophysiology in patient-variant neurons, subcellular mislocalization in HEK cells, and in vivo KO mouse phenotype with EEG readout","pmids":["38495551"],"is_preprint":false},{"year":2021,"finding":"SLITRK3 gene amplification in lung squamous cell carcinoma (LUSC) leads to SLITRK3-dependent activation of NTRK3 (TrkC), promoting a cancer stem cell phenotype. SLITRK3-dependent NTRK3 activation was demonstrated by sphere-formation assay and CD133-positive cell fraction analysis, and was inhibited by NTRK-targeted inhibitors.","method":"In situ immunofluorescence, sphere-formation assay, FACS analysis of CD133+ fraction, pharmacological inhibition of NTRK in LUSC cell lines","journal":"Molecular biomedicine","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, indirect activation of NTRK3 inferred from cell-based assays without direct biochemical demonstration of the SLITRK3-NTRK3 interaction mechanism","pmids":["35006496"],"is_preprint":false}],"current_model":"SLITRK3 is a single-pass postsynaptic transmembrane protein with extracellular LRR domains that selectively organizes inhibitory (GABAergic) synapses by trans-interacting with presynaptic PTPδ to induce inhibitory presynaptic differentiation, cis-interacting with postsynaptic Neuroligin 2 (NL2) with nanomolar affinity to synergistically promote GABAergic synapse maturation, interacting in trans with ErbB4 (via ErbB4's extracellular RLD domain) to support inhibitory synapse formation, and interacting with gephyrin for synapse stabilization; its conserved intracellular tyrosine Y969 is required for functional synapse development, and loss-of-function in mice and humans results in decreased inhibitory synapses, spontaneous epileptiform activity, and epileptic encephalopathy."},"narrative":{"mechanistic_narrative":"SLITRK3 is a postsynaptic single-pass transmembrane adhesion molecule that selectively organizes inhibitory (GABAergic) synapses in the brain [PMID:22286174, PMID:14557068]. Through its extracellular domains it engages the axonal receptor protein tyrosine phosphatase PTPδ in trans to drive inhibitory presynaptic differentiation, and SLITRK3-deficient neurons show reduced inhibitory synapse number and function with increased seizure susceptibility [PMID:22286174]. SLITRK3 acts within a larger inhibitory synaptic organizing assembly: it binds Neuroligin 2 in cis with nanomolar affinity to synergistically promote mature GABAergic synapse development [PMID:29107521], interacts in trans with the ErbB4 extracellular RLD domain to promote inhibitory synapse formation onto pyramidal neurons independently of ErbB4 kinase activity [PMID:34226493], and associates with gephyrin as part of postsynaptic stabilization [PMID:34735259]. Trans-synaptic complex formation with LAR-RPTPs proceeds via reciprocal higher-order clustering that can be dismantled by competing heparan sulfate [PMID:29081732]. A conserved intracellular tyrosine, Y969, is dispensable for surface trafficking and homodimerization but required for GABAergic synapse development and transmission [PMID:31551708]. Biallelic loss-of-function variants in SLITRK3 cause epileptic encephalopathy, with patient mutations causing Golgi accumulation and reduced surface expression, diminished GABAergic transmission in neurons, and spontaneous epileptiform activity with loss of parvalbumin interneurons in knockout mice [PMID:38495551].","teleology":[{"year":2003,"claim":"Established SLITRK3's protein architecture and tissue distribution, framing it as a candidate brain adhesion/signaling molecule before any synaptic function was known.","evidence":"Genomic and domain characterization with brain-enriched expression profiling","pmids":["14557068"],"confidence":"Medium","gaps":["No functional or synaptic role tested","Binding partners unidentified"]},{"year":2012,"claim":"Resolved what SLITRK3 actually does — it is a postsynaptic organizer that selectively induces GABAergic, not excitatory, presynaptic differentiation via trans-synaptic PTPδ binding, linking it to seizure phenotypes.","evidence":"Heterologous synaptogenesis (fibroblast co-culture), knockout mouse electrophysiology/EEG, trans-interaction assay with PTPδ","pmids":["22286174"],"confidence":"High","gaps":["Postsynaptic cis-partners not yet defined","Intracellular signaling requirements unknown"]},{"year":2017,"claim":"Identified a postsynaptic cis-partnership — SLITRK3 binds Neuroligin 2 with nanomolar affinity, showing the two cooperate to build mature inhibitory synapses rather than acting independently.","evidence":"Co-immunoprecipitation, binding affinity measurement, genetic perturbation in hippocampal neurons, electrophysiology and seizure assays","pmids":["29107521"],"confidence":"High","gaps":["Stoichiometry of NL2-ST3-PTPδ assembly unresolved","How cis and trans interactions are coordinated unclear"]},{"year":2017,"claim":"Provided structural logic for trans-synaptic assembly, showing LAR-RPTP/SLITRK3 complexes form higher-order clusters that heparan sulfate can competitively disassemble, implying a regulated switch.","evidence":"Crystal structure of related LAR-RPTP/IL1RAPL1 complex, clustering and competitive binding assays","pmids":["29081732"],"confidence":"Medium","gaps":["SLITRK3-specific structural data inferred from related complex","Physiological trigger for heparan sulfate competition not established"]},{"year":2019,"claim":"Localized the functional requirement to a specific intracellular residue — Y969 is needed for GABAergic synapse development and gephyrin clustering but not for trafficking or dimerization, separating signaling from adhesion functions.","evidence":"Site-directed mutagenesis with rescue, electrophysiology, gephyrin immunostaining, surface trafficking assay","pmids":["31551708"],"confidence":"High","gaps":["Whether Y969 is phosphorylated and by which kinase not shown","Intracellular effectors binding Y969 unidentified"]},{"year":2021,"claim":"Added a second trans-synaptic partner, ErbB4, acting through its RLD domain independent of kinase activity, broadening the receptor repertoire driving inhibitory synapse formation.","evidence":"Co-IP/pulldown, domain-deletion synaptogenesis assay, kinase-dead knock-in mice, electrophysiology","pmids":["34226493"],"confidence":"High","gaps":["How ErbB4 and PTPδ trans-interactions are coordinated unclear","Cell-type specificity of each partner not fully mapped"]},{"year":2021,"claim":"Placed SLITRK3 in a postsynaptic stabilization mechanism by linking it to gephyrin downstream of A2A/GABAAR signaling and PKA-mediated gephyrin phosphorylation.","evidence":"Co-IP of gephyrin and SLITRK3, gephyrin S303 phosphorylation mutagenesis, pharmacology, live imaging","pmids":["34735259"],"confidence":"Medium","gaps":["SLITRK3-gephyrin binding evidence partially inferred","Direct vs. indirect association not resolved"]},{"year":2021,"claim":"Reported a distinct disease context in which SLITRK3 amplification activates NTRK3 to promote a cancer stem cell phenotype in lung squamous carcinoma.","evidence":"Immunofluorescence, sphere-formation and CD133+ FACS assays, NTRK inhibitor treatment in LUSC lines","pmids":["35006496"],"confidence":"Low","gaps":["Direct SLITRK3-NTRK3 interaction not demonstrated biochemically","Single-lab, indirect activation inference","Relevance to neuronal NTRK signaling untested"]},{"year":2024,"claim":"Established SLITRK3 as a human disease gene — biallelic loss-of-function causes epileptic encephalopathy through Golgi retention, loss of surface expression, and reduced GABAergic transmission, recapitulated by knockout mouse phenotypes.","evidence":"Patient-derived neuron electrophysiology, HEK surface/Golgi localization imaging, KO mouse EEG and behavior","pmids":["38495551"],"confidence":"High","gaps":["Whether all patient variants act via the same trafficking defect unknown","Parvalbumin interneuron loss mechanism not dissected"]},{"year":null,"claim":"How SLITRK3 coordinates its multiple cis (NL2) and trans (PTPδ, ErbB4) partners and how Y969 transduces an intracellular signal to gephyrin remain unresolved.","evidence":"","pmids":[],"confidence":"High","gaps":["No identified kinase or effector acting on Y969","Stoichiometry/order of multi-partner assembly unknown","Structural model of the full postsynaptic complex absent"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098631","term_label":"cell adhesion mediator activity","supporting_discovery_ids":[0,1,3]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,2,7]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[7]}],"pathway":[{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[0,1]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[0,3]}],"complexes":["trans-synaptic LAR-RPTP/SLITRK3 adhesion complex"],"partners":["PTPRD","NLGN2","ERBB4","GPHN"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O94933","full_name":"SLIT and NTRK-like protein 3","aliases":[],"length_aa":977,"mass_kda":108.9,"function":"Suppresses neurite outgrowth","subcellular_location":"Membrane","url":"https://www.uniprot.org/uniprotkb/O94933/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/SLITRK3","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/SLITRK3","total_profiled":1310},"omim":[{"mim_id":"609679","title":"SLIT- AND NTRK-LIKE FAMILY, MEMBER 3; SLITRK3","url":"https://www.omim.org/entry/609679"},{"mim_id":"601598","title":"PROTEIN-TYROSINE PHOSPHATASE, RECEPTOR-TYPE, DELTA; PTPRD","url":"https://www.omim.org/entry/601598"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Mitochondria","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"brain","ntpm":9.3},{"tissue":"fallopian tube","ntpm":13.0}],"url":"https://www.proteinatlas.org/search/SLITRK3"},"hgnc":{"alias_symbol":["KIAA0848"],"prev_symbol":[]},"alphafold":{"accession":"O94933","domains":[{"cath_id":"3.80.10.10","chopping":"50-208","consensus_level":"high","plddt":90.3515,"start":50,"end":208},{"cath_id":"3.80.10.10","chopping":"381-513","consensus_level":"high","plddt":88.9492,"start":381,"end":513}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O94933","model_url":"https://alphafold.ebi.ac.uk/files/AF-O94933-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O94933-F1-predicted_aligned_error_v6.png","plddt_mean":63.78},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=SLITRK3","jax_strain_url":"https://www.jax.org/strain/search?query=SLITRK3"},"sequence":{"accession":"O94933","fasta_url":"https://rest.uniprot.org/uniprotkb/O94933.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O94933/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O94933"}},"corpus_meta":[{"pmid":"24821223","id":"PMC_24821223","title":"Genome-wide 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(2012)","url":"https://pubmed.ncbi.nlm.nih.gov/40213228","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":12015,"output_tokens":2835,"usd":0.039285,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10171,"output_tokens":3150,"usd":0.064802,"stage2_stop_reason":"end_turn"},"total_usd":0.104087,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2012,\n      \"finding\": \"Slitrk3 acts as a postsynaptic adhesion molecule that selectively induces inhibitory (GABAergic) presynaptic differentiation via trans-synaptic interaction with axonal PTPδ (receptor protein tyrosine phosphatase delta). When expressed in fibroblasts, Slitrk3 triggered only inhibitory presynaptic differentiation in contacting axons of co-cultured hippocampal neurons. Recombinant Slitrk3 preferentially localized to inhibitory postsynaptic sites. Slitrk3-deficient mice showed decreased inhibitory synapse number and function in hippocampal CA1 neurons and increased seizure susceptibility.\",\n      \"method\": \"Heterologous cell synaptogenesis assay (fibroblast co-culture), recombinant protein localization, Slitrk3 knockout mouse analysis (electrophysiology, immunostaining, EEG), trans-interaction assay with PTPδ\",\n      \"journal\": \"Nature neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — multiple orthogonal methods including heterologous expression assay, knockout mouse phenotyping, and direct binding studies; replicated in subsequent papers\",\n      \"pmids\": [\"22286174\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Slitrk3 (ST3) interacts with Neuroligin 2 (NL2) through their extracellular domains with nanomolar affinity in a cis interaction. During neuronal maturation, both NL2 and ST3 are required together for inhibitory synapse development; selective perturbation of the NL2-ST3 interaction impairs inhibitory synapse development, disrupts hippocampal network activity, and increases seizure susceptibility. NL2 is required for establishing GABAergic transmission in developing neurons, while mature inhibitory synapse development requires both NL2 and ST3 acting synergistically.\",\n      \"method\": \"Co-immunoprecipitation, binding affinity measurements, hippocampal neuron culture with genetic perturbation, electrophysiology, seizure susceptibility assays\",\n      \"journal\": \"Neuron\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — binding affinity quantified, reciprocal interaction demonstrated, functional rescue experiments, multiple orthogonal methods in a single rigorous study\",\n      \"pmids\": [\"29107521\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"The conserved tyrosine residue Y969 in the intracellular C-terminus of Slitrk3 is critical for GABAergic synapse development. Overexpression of the Y969A mutant markedly reduced gephyrin puncta density and GABAergic transmission in hippocampal neurons. Wild-type ST3, but not ST3 Y969A, rescued GABAergic transmission deficits in neurons lacking endogenous ST3. The C-terminus is not required for ST3 homo-dimerization or trafficking to the cell surface in heterologous cells.\",\n      \"method\": \"Site-directed mutagenesis, overexpression and rescue experiments in hippocampal neurons, electrophysiology, immunostaining for gephyrin puncta, heterologous cell surface trafficking assay\",\n      \"journal\": \"Frontiers in molecular neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — active-site/residue mutagenesis combined with functional rescue and electrophysiology in a single focused study\",\n      \"pmids\": [\"31551708\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"ErbB4 interacts in trans with Slitrk3 through the extracellular RLD domain of ErbB4 to promote inhibitory synapse formation onto pyramidal neurons independently of ErbB4 kinase activity. Deletion of the RLD domain abolished induction of gephyrin and GABAAR α1 puncta by ErbB4. Disruption of the ErbB4-Slitrk3 interaction by secretable RLD decreased inhibitory synapses and impaired GABAergic transmission.\",\n      \"method\": \"Co-immunoprecipitation/pulldown of ErbB4 and Slitrk3, heterologous cell co-culture synaptogenesis assay, domain deletion mutants, kinase-dead knock-in mice, electrophysiology\",\n      \"journal\": \"Translational psychiatry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — direct binding demonstrated by co-IP, domain deletion, functional consequence confirmed by electrophysiology in neurons and in vivo knock-in mouse\",\n      \"pmids\": [\"34226493\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Gephyrin interacts with Slitrk3 as part of the synapse stabilization mechanism downstream of adenosine A2A receptor and GABAAR activation. PKA-mediated phosphorylation of gephyrin on serine 303 is required for GABAAR stabilization, and stabilization of pre- and postsynaptic GABAergic elements involves the gephyrin-Slitrk3 interaction.\",\n      \"method\": \"Co-immunoprecipitation of gephyrin and Slitrk3, phosphorylation site mutagenesis (gephyrin S303), pharmacological receptor activation/inhibition, live imaging of synapse stability\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — gephyrin-Slitrk3 interaction detected by co-IP; phosphorylation and functional consequence shown in same study, but Slitrk3-specific binding evidence is partially inferred from abstract description\",\n      \"pmids\": [\"34735259\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"LAR-RPTP (PTPδ) binding to Slitrk3 (as well as IL1RAPL1 and IL-1RAcP) induces reciprocal higher-order clustering of trans-synaptic adhesion complexes. Crystal structure of LAR-RPTP/IL1RAPL1 complex reveals lateral interactions critical for higher-order assembly; competitive binding of heparan sulfate to LAR-RPTP can dismantle pre-established LAR-RPTP/Slitrk3 trans-synaptic complexes.\",\n      \"method\": \"Crystal structure determination, cell clustering assay, competitive binding with heparan sulfate, synaptogenesis assay in HEK cell co-culture\",\n      \"journal\": \"Frontiers in molecular neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — crystal structure of related complex, functional clustering assay, but Slitrk3-specific structural data is inferred from the broader LAR-RPTP study\",\n      \"pmids\": [\"29081732\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"SLITRK3 protein is characterized as an integral membrane protein with two leucine-rich repeat (LRR) domains similar to Slit proteins and a C-terminal domain partially similar to Trk neurotrophin receptors. It is expressed predominantly in the brain.\",\n      \"method\": \"Genomic organization analysis, expression profiling (Northern blot/RT-PCR), protein domain characterization\",\n      \"journal\": \"Gene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct experimental characterization of protein domain architecture and tissue expression, though functional mechanistic consequence not tested in this paper\",\n      \"pmids\": [\"14557068\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Biallelic loss-of-function variants in SLITRK3 (C566R and E606X) cause epileptic encephalopathy. Patient variants C566R and E606X alter SLITRK3 protein surface expression by causing accumulation in the Golgi apparatus. Primary hippocampal neuron cultures carrying patient variants show reduced GABAergic transmission (confirmed by electrophysiology). SLITRK3 KO mice exhibit spontaneous epileptiform EEG activity, enhanced pentylenetetrazole-induced seizures, increased motor activity, and reduced parvalbumin interneurons.\",\n      \"method\": \"Patient-derived neuron cultures, electrophysiology, immunostaining of HEK-293 cells (cell surface vs. Golgi localization), SLITRK3 knockout mouse EEG and behavioral analysis\",\n      \"journal\": \"Frontiers in molecular neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — loss-of-function demonstrated by electrophysiology in patient-variant neurons, subcellular mislocalization in HEK cells, and in vivo KO mouse phenotype with EEG readout\",\n      \"pmids\": [\"38495551\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"SLITRK3 gene amplification in lung squamous cell carcinoma (LUSC) leads to SLITRK3-dependent activation of NTRK3 (TrkC), promoting a cancer stem cell phenotype. SLITRK3-dependent NTRK3 activation was demonstrated by sphere-formation assay and CD133-positive cell fraction analysis, and was inhibited by NTRK-targeted inhibitors.\",\n      \"method\": \"In situ immunofluorescence, sphere-formation assay, FACS analysis of CD133+ fraction, pharmacological inhibition of NTRK in LUSC cell lines\",\n      \"journal\": \"Molecular biomedicine\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, indirect activation of NTRK3 inferred from cell-based assays without direct biochemical demonstration of the SLITRK3-NTRK3 interaction mechanism\",\n      \"pmids\": [\"35006496\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"SLITRK3 is a single-pass postsynaptic transmembrane protein with extracellular LRR domains that selectively organizes inhibitory (GABAergic) synapses by trans-interacting with presynaptic PTPδ to induce inhibitory presynaptic differentiation, cis-interacting with postsynaptic Neuroligin 2 (NL2) with nanomolar affinity to synergistically promote GABAergic synapse maturation, interacting in trans with ErbB4 (via ErbB4's extracellular RLD domain) to support inhibitory synapse formation, and interacting with gephyrin for synapse stabilization; its conserved intracellular tyrosine Y969 is required for functional synapse development, and loss-of-function in mice and humans results in decreased inhibitory synapses, spontaneous epileptiform activity, and epileptic encephalopathy.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"SLITRK3 is a postsynaptic single-pass transmembrane adhesion molecule that selectively organizes inhibitory (GABAergic) synapses in the brain [#0, #6]. Through its extracellular domains it engages the axonal receptor protein tyrosine phosphatase PTPδ in trans to drive inhibitory presynaptic differentiation, and SLITRK3-deficient neurons show reduced inhibitory synapse number and function with increased seizure susceptibility [#0]. SLITRK3 acts within a larger inhibitory synaptic organizing assembly: it binds Neuroligin 2 in cis with nanomolar affinity to synergistically promote mature GABAergic synapse development [#1], interacts in trans with the ErbB4 extracellular RLD domain to promote inhibitory synapse formation onto pyramidal neurons independently of ErbB4 kinase activity [#3], and associates with gephyrin as part of postsynaptic stabilization [#4]. Trans-synaptic complex formation with LAR-RPTPs proceeds via reciprocal higher-order clustering that can be dismantled by competing heparan sulfate [#5]. A conserved intracellular tyrosine, Y969, is dispensable for surface trafficking and homodimerization but required for GABAergic synapse development and transmission [#2]. Biallelic loss-of-function variants in SLITRK3 cause epileptic encephalopathy, with patient mutations causing Golgi accumulation and reduced surface expression, diminished GABAergic transmission in neurons, and spontaneous epileptiform activity with loss of parvalbumin interneurons in knockout mice [#7].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Established SLITRK3's protein architecture and tissue distribution, framing it as a candidate brain adhesion/signaling molecule before any synaptic function was known.\",\n      \"evidence\": \"Genomic and domain characterization with brain-enriched expression profiling\",\n      \"pmids\": [\"14557068\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No functional or synaptic role tested\", \"Binding partners unidentified\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Resolved what SLITRK3 actually does — it is a postsynaptic organizer that selectively induces GABAergic, not excitatory, presynaptic differentiation via trans-synaptic PTPδ binding, linking it to seizure phenotypes.\",\n      \"evidence\": \"Heterologous synaptogenesis (fibroblast co-culture), knockout mouse electrophysiology/EEG, trans-interaction assay with PTPδ\",\n      \"pmids\": [\"22286174\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Postsynaptic cis-partners not yet defined\", \"Intracellular signaling requirements unknown\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identified a postsynaptic cis-partnership — SLITRK3 binds Neuroligin 2 with nanomolar affinity, showing the two cooperate to build mature inhibitory synapses rather than acting independently.\",\n      \"evidence\": \"Co-immunoprecipitation, binding affinity measurement, genetic perturbation in hippocampal neurons, electrophysiology and seizure assays\",\n      \"pmids\": [\"29107521\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry of NL2-ST3-PTPδ assembly unresolved\", \"How cis and trans interactions are coordinated unclear\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Provided structural logic for trans-synaptic assembly, showing LAR-RPTP/SLITRK3 complexes form higher-order clusters that heparan sulfate can competitively disassemble, implying a regulated switch.\",\n      \"evidence\": \"Crystal structure of related LAR-RPTP/IL1RAPL1 complex, clustering and competitive binding assays\",\n      \"pmids\": [\"29081732\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"SLITRK3-specific structural data inferred from related complex\", \"Physiological trigger for heparan sulfate competition not established\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Localized the functional requirement to a specific intracellular residue — Y969 is needed for GABAergic synapse development and gephyrin clustering but not for trafficking or dimerization, separating signaling from adhesion functions.\",\n      \"evidence\": \"Site-directed mutagenesis with rescue, electrophysiology, gephyrin immunostaining, surface trafficking assay\",\n      \"pmids\": [\"31551708\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Y969 is phosphorylated and by which kinase not shown\", \"Intracellular effectors binding Y969 unidentified\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Added a second trans-synaptic partner, ErbB4, acting through its RLD domain independent of kinase activity, broadening the receptor repertoire driving inhibitory synapse formation.\",\n      \"evidence\": \"Co-IP/pulldown, domain-deletion synaptogenesis assay, kinase-dead knock-in mice, electrophysiology\",\n      \"pmids\": [\"34226493\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How ErbB4 and PTPδ trans-interactions are coordinated unclear\", \"Cell-type specificity of each partner not fully mapped\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Placed SLITRK3 in a postsynaptic stabilization mechanism by linking it to gephyrin downstream of A2A/GABAAR signaling and PKA-mediated gephyrin phosphorylation.\",\n      \"evidence\": \"Co-IP of gephyrin and SLITRK3, gephyrin S303 phosphorylation mutagenesis, pharmacology, live imaging\",\n      \"pmids\": [\"34735259\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"SLITRK3-gephyrin binding evidence partially inferred\", \"Direct vs. indirect association not resolved\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Reported a distinct disease context in which SLITRK3 amplification activates NTRK3 to promote a cancer stem cell phenotype in lung squamous carcinoma.\",\n      \"evidence\": \"Immunofluorescence, sphere-formation and CD133+ FACS assays, NTRK inhibitor treatment in LUSC lines\",\n      \"pmids\": [\"35006496\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Direct SLITRK3-NTRK3 interaction not demonstrated biochemically\", \"Single-lab, indirect activation inference\", \"Relevance to neuronal NTRK signaling untested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Established SLITRK3 as a human disease gene — biallelic loss-of-function causes epileptic encephalopathy through Golgi retention, loss of surface expression, and reduced GABAergic transmission, recapitulated by knockout mouse phenotypes.\",\n      \"evidence\": \"Patient-derived neuron electrophysiology, HEK surface/Golgi localization imaging, KO mouse EEG and behavior\",\n      \"pmids\": [\"38495551\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether all patient variants act via the same trafficking defect unknown\", \"Parvalbumin interneuron loss mechanism not dissected\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How SLITRK3 coordinates its multiple cis (NL2) and trans (PTPδ, ErbB4) partners and how Y969 transduces an intracellular signal to gephyrin remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No identified kinase or effector acting on Y969\", \"Stoichiometry/order of multi-partner assembly unknown\", \"Structural model of the full postsynaptic complex absent\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098631\", \"supporting_discovery_ids\": [0, 1, 3]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 2, 7]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [7]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [0, 3]}\n    ],\n    \"complexes\": [\"trans-synaptic LAR-RPTP/SLITRK3 adhesion complex\"],\n    \"partners\": [\"PTPRD\", \"NLGN2\", \"ERBB4\", \"GPHN\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"faith_supported":5,"faith_total":6,"faith_pct":83.33333333333333}}