{"gene":"KCNIP4","run_date":"2026-06-10T02:59:49","timeline":{"discoveries":[{"year":2002,"finding":"CALP/KChIP4 directly binds the C-terminal region of presenilin 2 (PS2) and co-localizes with PS2 in the endoplasmic reticulum upon co-expression in cultured cells. Overexpression of CALP did not affect PS complex metabolism/stability or gamma-cleavage of betaAPP or Notch site 3 cleavage.","method":"Co-immunoprecipitation, co-expression in cultured cells, co-localization imaging","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding and co-localization shown, but single lab with co-IP and imaging only; functional effect on PS complex was negative","pmids":["11847232"],"is_preprint":false},{"year":2002,"finding":"CALP/KChIP4 directly binds voltage-gated potassium channel subunit Kv4.2 and, upon co-expression, reconstitutes A-type K+ current features, establishing CALP/KChIP4 as a functional component of native Kv4 channel complexes.","method":"Co-immunoprecipitation, co-expression electrophysiology (reconstitution of A-type K+ currents in cultured cells)","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct binding assay combined with functional reconstitution of A-type K+ current; replicated in subsequent studies","pmids":["11847232"],"is_preprint":false},{"year":2004,"finding":"KChIP4 splice variant A (KChIP4A), but not splice variant B, slows Kv4 current inactivation to >100 ms when expressed in neurons. Cell-type-specific expression of KChIP4A (detected in globus pallidus and basal forebrain neurons but absent in striatal cholinergic interneurons and hippocampal CA1 pyramidal neurons by single-cell RT-PCR) correlates with the presence of a slowly inactivating component of A-type current.","method":"Single-cell RT-PCR in acutely dissociated rat neurons, Xenopus oocyte electrophysiology","journal":"The European journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — single-cell RT-PCR combined with electrophysiology, single lab, consistent mechanistic correlation","pmids":["15233748"],"is_preprint":false},{"year":2005,"finding":"The KChIP4 gene is regulated by at least two alternative promoters: a 325 bp fragment upstream of KChIP4.1 and an 818 bp fragment at the 5' end of KChIP4.4, both capable of driving reporter gene transcription in HT1080 cells and rat fetal brain neurons, and both contain CG islands but lack canonical TATA and CAAT boxes.","method":"Cloning and functional reporter gene assays (luciferase/reporter in HT1080 cells and primary neurons), RT-PCR identification of splice variants","journal":"Acta biochimica et biophysica Sinica","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional promoter assay in two cell types, single lab","pmids":["15806290"],"is_preprint":false},{"year":2008,"finding":"CALP/KChIP4 binds directly to the cytoplasmic tail of GalT2 (UDP-Gal:GA2/GM2/GD2 beta-1,3-galactosyltransferase) in vitro and in CHO-K1 cells. Expression of CALP redistributes GalT2, SialT2, and GalNAcT from the Golgi to the ER, suggesting CALP/KChIP4 is involved in the trafficking of Golgi glycosyltransferases.","method":"Yeast two-hybrid, in vitro binding (immobilized recombinant CALP, peptide pulldown), co-immunoprecipitation in CHO-K1 cells, immunofluorescence localization","journal":"The Biochemical journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal binding methods (yeast two-hybrid, in vitro pulldown, co-IP in mammalian cells) plus functional localization readout, single lab","pmids":["18269347"],"is_preprint":false},{"year":2010,"finding":"KChIP2, KChIP3, and KChIP4 all co-immunoprecipitate with Kv4.2 in adult mouse posterior cortex. Simultaneous RNA interference-induced knockdown of KChIP2, KChIP3, and KChIP4 together markedly reduces I_A density and produces Kv current remodeling in cortical pyramidal neurons, demonstrating interdependent roles for these three KChIP subunits in Kv4-encoded I_A channel generation.","method":"Co-immunoprecipitation, RNA interference (siRNA/shRNA), whole-cell patch-clamp electrophysiology in cortical pyramidal neurons, genetic knockout mice (KChIP2-/-, KChIP3-/-)","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, genetic KO mouse models, and RNAi with direct electrophysiological readout; multiple orthogonal methods in single study","pmids":["20943905"],"is_preprint":false},{"year":2019,"finding":"kcnip4 is a direct target of miR-3068-3p in rat cortical neurons; miR-3068-3p inhibition increases kcnip4 protein expression, enhances I_A (A-type K+ current) density, and protects against glutamate-induced excitotoxicity. Knockdown of kcnip4 by shRNA abolishes the neuroprotective effect of miR-3068-3p inhibition, and overexpression of kcnip4 alone is sufficient to confer neuroprotection, acting via upregulation of I_A.","method":"Luciferase reporter assay (miRNA target validation), western blot, shRNA knockdown, lentiviral overexpression, whole-cell patch-clamp electrophysiology, cell viability assays in rat primary cortical neurons","journal":"Journal of neurochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — luciferase target validation, shRNA KD, OE rescue, and electrophysiology; single lab with multiple orthogonal methods","pmids":["31792968"],"is_preprint":false},{"year":2020,"finding":"A missense mutation (W→R) in a highly conserved region of KCNIP4 causes a dramatic reduction in KCNIP4 protein expression in the cerebellum of affected Norwegian Buhund dogs and is associated with progressive cerebellar ataxia, establishing an essential role for KCNIP4 in cerebellar Kv4 channel complex function.","method":"Whole-genome sequencing, Sanger sequencing genotyping, western blot, immunohistochemistry in cerebellar tissue, RT-PCR for transcript characterization","journal":"PLoS genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function variant with protein expression confirmation by western blot and IHC, defined cerebellar phenotype; single study in a canine model","pmids":["31999692"],"is_preprint":false},{"year":2024,"finding":"AAV-mediated overexpression of Kcnip4 in a humanized Alzheimer's disease mouse model reduced expression of activity-dependent genes Arc and c-Fos, suggesting that KCNIP4 acts as a compensatory mechanism against neuronal hyperexcitability in the context of AD pathology.","method":"AAV-mediated gene overexpression in humanized AD mouse model, gene expression analysis (Arc, c-Fos)","journal":"bioRxiv (preprint)","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single in vivo overexpression experiment in a preprint, no mechanistic dissection of pathway, single lab","pmids":["bio_10.1101_2024.11.03.621787"],"is_preprint":true}],"current_model":"KCNIP4 (CALP/KChIP4) is an EF-hand calcium-binding protein that functions as an accessory subunit of native neuronal Kv4 channel complexes by directly binding Kv4.2, modulating A-type K+ current kinetics (with splice variant KChIP4A specifically slowing inactivation), acting interdependently with KChIP2 and KChIP3 to generate cortical I_A; it also interacts with presenilin 2 at the ER (without affecting gamma-secretase activity), binds the cytoplasmic tail of Golgi glycosyltransferases to influence their trafficking, is post-transcriptionally regulated by miR-3068-3p, and loss-of-function mutations cause cerebellar ataxia in dogs."},"narrative":{"mechanistic_narrative":"KCNIP4 (CALP/KChIP4) is an EF-hand-type accessory subunit of neuronal Kv4 voltage-gated potassium channel complexes that shapes the A-type K+ current (I_A) governing neuronal excitability [PMID:11847232, PMID:20943905]. It binds directly to Kv4.2 and, on co-expression, reconstitutes A-type K+ current features, establishing it as a functional component of native Kv4 complexes [PMID:11847232]; in adult cortical pyramidal neurons KChIP4 acts interdependently with KChIP2 and KChIP3, all three co-assembling with Kv4.2, such that their simultaneous knockdown markedly reduces I_A density [PMID:20943905]. The KChIP4A splice variant confers a distinctive slowing of Kv4 inactivation, and its cell-type-restricted expression correlates with a slowly inactivating I_A component in specific neuronal populations [PMID:15233748]. Through its control of I_A, KCNIP4 sets neuroprotective tone: it is a direct target of miR-3068-3p, and relieving this repression raises KChIP4 protein and I_A density to protect cortical neurons from glutamate excitotoxicity [PMID:31792968]. Beyond channel modulation, KCNIP4 has separable trafficking and protein-interaction roles: it binds the C-terminal region of presenilin 2 and co-localizes with it in the ER without affecting gamma-secretase activity [PMID:11847232], and it binds the cytoplasmic tail of the Golgi glycosyltransferase GalT2 and redistributes Golgi glycosyltransferases to the ER [PMID:18269347]. A loss-of-function missense mutation that depletes KCNIP4 protein in the cerebellum causes progressive cerebellar ataxia in dogs, demonstrating an essential in vivo role for the protein [PMID:31999692].","teleology":[{"year":2002,"claim":"Established the two principal molecular interactions of CALP/KChIP4 — defining it both as a Kv4 channel partner and as a presenilin 2-interacting ER protein — and distinguished a functional from a non-functional engagement.","evidence":"Co-immunoprecipitation, co-expression electrophysiology, and co-localization imaging in cultured cells","pmids":["11847232"],"confidence":"High","gaps":["Structural basis of Kv4.2 binding not resolved","Biological consequence of the PS2 interaction left unexplained given no effect on gamma-secretase","Calcium-dependence of these interactions not tested"]},{"year":2004,"claim":"Resolved how splice diversity tunes channel kinetics by showing KChIP4A, but not variant B, slows Kv4 inactivation and that its restricted expression accounts for cell-type-specific slowly inactivating I_A.","evidence":"Single-cell RT-PCR in dissociated rat neurons combined with Xenopus oocyte electrophysiology","pmids":["15233748"],"confidence":"Medium","gaps":["Domain within KChIP4A responsible for slowed inactivation not mapped","Native confirmation in the implicated neuron types limited to expression correlation"]},{"year":2005,"claim":"Clarified the transcriptional architecture of the locus by identifying two alternative promoters driving distinct splice variants, providing a basis for variant-specific expression.","evidence":"Reporter gene assays in HT1080 cells and primary neurons plus RT-PCR variant identification","pmids":["15806290"],"confidence":"Medium","gaps":["Trans-acting factors controlling each promoter not identified","Cell-type specificity of promoter usage not demonstrated in vivo"]},{"year":2008,"claim":"Extended KCNIP4 function beyond ion channels by demonstrating direct binding to a Golgi glycosyltransferase cytoplasmic tail and a role in glycosyltransferase trafficking.","evidence":"Yeast two-hybrid, in vitro pulldown, co-IP in CHO-K1 cells, and immunofluorescence localization","pmids":["18269347"],"confidence":"Medium","gaps":["Physiological relevance of glycosyltransferase redistribution in neurons untested","Whether this role is calcium-regulated unknown"]},{"year":2010,"claim":"Demonstrated that KChIP4 operates non-redundantly with KChIP2 and KChIP3 in native cortical neurons to generate Kv4-encoded I_A, moving from heterologous reconstitution to endogenous channel biology.","evidence":"Reciprocal Co-IP, triple RNAi knockdown, KChIP knockout mice, and whole-cell patch-clamp in cortical pyramidal neurons","pmids":["20943905"],"confidence":"High","gaps":["Individual contribution of KChIP4 alone not isolated by single knockdown","Stoichiometry of the multi-KChIP/Kv4.2 complex not defined"]},{"year":2019,"claim":"Placed KCNIP4 in a post-transcriptional regulatory and neuroprotective pathway, showing that miR-3068-3p repression of kcnip4 controls I_A density and resistance to excitotoxicity.","evidence":"Luciferase target validation, shRNA knockdown, lentiviral overexpression rescue, and electrophysiology in rat cortical neurons","pmids":["31792968"],"confidence":"Medium","gaps":["In vivo relevance of the miR-3068-3p/kcnip4 axis not tested","Downstream signaling linking I_A to excitotoxicity protection not dissected"]},{"year":2020,"claim":"Provided in vivo genetic evidence that KCNIP4 is essential, with a loss-of-function mutation depleting cerebellar protein and causing progressive ataxia.","evidence":"Whole-genome and Sanger sequencing, western blot, and immunohistochemistry in affected Norwegian Buhund dogs","pmids":["31999692"],"confidence":"Medium","gaps":["Mechanistic link between protein loss and cerebellar dysfunction at the channel level not directly demonstrated","Relevance to human ataxia not established"]},{"year":2024,"claim":"Linked KCNIP4 to disease-relevant neuronal hyperexcitability, indicating it can dampen activity-dependent gene expression in an Alzheimer's disease context.","evidence":"AAV-mediated Kcnip4 overexpression in a humanized AD mouse model with Arc/c-Fos expression readout (preprint)","pmids":["bio_10.1101_2024.11.03.621787"],"confidence":"Low","gaps":["Single overexpression experiment in a preprint, no mechanistic dissection","Whether the effect is mediated through Kv4/I_A not shown","No behavioral or pathological outcome measured"]},{"year":null,"claim":"How KCNIP4's calcium sensing, splice-variant-specific kinetic effects, and its non-channel roles in ER/Golgi trafficking are coordinated within neurons remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of the KCNIP4/Kv4 complex in the corpus","Calcium-dependence of KCNIP4 interactions not directly demonstrated","Relationship between channel-modulatory and trafficking functions unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,2,5]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[0,4]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[4]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1,5]}],"pathway":[{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[1,5]}],"complexes":["Kv4 channel complex"],"partners":["KCND2","PSEN2","KCNIP2","KCNIP3","B3GALT4"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q6PIL6","full_name":"Kv channel-interacting protein 4","aliases":["A-type potassium channel modulatory protein 4","Calsenilin-like protein","Potassium channel-interacting protein 4"],"length_aa":250,"mass_kda":28.7,"function":"Regulatory subunit of Kv4/D (Shal)-type voltage-gated rapidly inactivating A-type potassium channels. Modulates KCND2 channel density, inactivation kinetics and rate of recovery from inactivation in a calcium-dependent and isoform-specific manner (PubMed:11847232, PubMed:18957440, PubMed:23576435). Modulates KCND3/Kv4.3 currents (PubMed:23576435). Isoform 4 does not increase KCND2 expression at the cell membrane (PubMed:18957440). Isoform 4 retains KCND3 in the endoplasmic reticulum and negatively regulates its expression at the cell membrane","subcellular_location":"Endoplasmic reticulum","url":"https://www.uniprot.org/uniprotkb/Q6PIL6/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/KCNIP4","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/KCNIP4","total_profiled":1310},"omim":[{"mim_id":"608182","title":"POTASSIUM CHANNEL-INTERACTING PROTEIN 4","url":"https://www.omim.org/entry/608182"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Vesicles","reliability":"Approved"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"brain","ntpm":36.4},{"tissue":"retina","ntpm":16.8}],"url":"https://www.proteinatlas.org/search/KCNIP4"},"hgnc":{"alias_symbol":["CALP","KCHIP4","MGC44947"],"prev_symbol":[]},"alphafold":{"accession":"Q6PIL6","domains":[{"cath_id":"1.10.238.10","chopping":"156-250","consensus_level":"medium","plddt":81.8867,"start":156,"end":250}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6PIL6","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q6PIL6-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q6PIL6-F1-predicted_aligned_error_v6.png","plddt_mean":69.81},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=KCNIP4","jax_strain_url":"https://www.jax.org/strain/search?query=KCNIP4"},"sequence":{"accession":"Q6PIL6","fasta_url":"https://rest.uniprot.org/uniprotkb/Q6PIL6.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q6PIL6/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q6PIL6"}},"corpus_meta":[{"pmid":"11847232","id":"PMC_11847232","title":"Molecular cloning and characterization of CALP/KChIP4, a novel EF-hand protein interacting with presenilin 2 and voltage-gated potassium channel subunit Kv4.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/11847232","citation_count":143,"is_preprint":false},{"pmid":"20943905","id":"PMC_20943905","title":"Interdependent roles for accessory KChIP2, KChIP3, and KChIP4 subunits in the generation of Kv4-encoded IA channels in cortical pyramidal neurons.","date":"2010","source":"The Journal of neuroscience : the official journal of the Society for Neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/20943905","citation_count":49,"is_preprint":false},{"pmid":"26169577","id":"PMC_26169577","title":"A genome-wide association study identifies variants in KCNIP4 associated with ACE inhibitor-induced cough.","date":"2015","source":"The pharmacogenomics journal","url":"https://pubmed.ncbi.nlm.nih.gov/26169577","citation_count":47,"is_preprint":false},{"pmid":"22981920","id":"PMC_22981920","title":"KCNIP4 as a candidate gene for personality disorders and adult ADHD.","date":"2012","source":"European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/22981920","citation_count":33,"is_preprint":false},{"pmid":"23457522","id":"PMC_23457522","title":"Integration of mouse and human genome-wide association data identifies KCNIP4 as an asthma gene.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23457522","citation_count":26,"is_preprint":false},{"pmid":"17981209","id":"PMC_17981209","title":"Mapping of constitutional translocation breakpoints in renal cell cancer patients: identification of KCNIP4 as a candidate gene.","date":"2007","source":"Cancer genetics and cytogenetics","url":"https://pubmed.ncbi.nlm.nih.gov/17981209","citation_count":20,"is_preprint":false},{"pmid":"18269347","id":"PMC_18269347","title":"Calsenilin and CALP interact with the cytoplasmic tail of UDP-Gal:GA2/GM2/GD2 beta-1,3-galactosyltransferase.","date":"2008","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/18269347","citation_count":17,"is_preprint":false},{"pmid":"31999692","id":"PMC_31999692","title":"Characterisation of canine KCNIP4: A novel gene for cerebellar ataxia identified by whole-genome sequencing two affected Norwegian Buhund dogs.","date":"2020","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/31999692","citation_count":16,"is_preprint":false},{"pmid":"15233748","id":"PMC_15233748","title":"Cell-type-specific splicing of KChIP4 mRNA correlates with slower kinetics of A-type current.","date":"2004","source":"The European journal of neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/15233748","citation_count":15,"is_preprint":false},{"pmid":"16759893","id":"PMC_16759893","title":"Significance of the extra C-terminal tail of CaLP, a novel calmodulin-like protein involved in oyster calcium metabolism.","date":"2006","source":"Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/16759893","citation_count":13,"is_preprint":false},{"pmid":"30105591","id":"PMC_30105591","title":"Molecular cloning and characterization of calmodulin-like protein CaLP from the Scleractinian coral Galaxea astreata.","date":"2018","source":"Cell stress & chaperones","url":"https://pubmed.ncbi.nlm.nih.gov/30105591","citation_count":8,"is_preprint":false},{"pmid":"31792968","id":"PMC_31792968","title":"Down-regulation of miR-3068-3p enhances kcnip4-regulated A-type potassium current to protect against glutamate-induced excitotoxicity.","date":"2019","source":"Journal of neurochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/31792968","citation_count":7,"is_preprint":false},{"pmid":"9485591","id":"PMC_9485591","title":"Isolation, purification and characterization of intracellular calmodulin like protein (CALP) from Mycobacterium phlei.","date":"1998","source":"FEMS microbiology letters","url":"https://pubmed.ncbi.nlm.nih.gov/9485591","citation_count":7,"is_preprint":false},{"pmid":"15806290","id":"PMC_15806290","title":"Identification of the alternative promoters of the KChIP4 subfamily.","date":"2005","source":"Acta biochimica et biophysica Sinica","url":"https://pubmed.ncbi.nlm.nih.gov/15806290","citation_count":6,"is_preprint":false},{"pmid":"18818969","id":"PMC_18818969","title":"Investigation of phosphorylation site responsible for CaLP (P. fucata) nucleo-cytoplasmic shuttling triggered by overexpression of p21Cip1.","date":"2008","source":"Marine biotechnology (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/18818969","citation_count":2,"is_preprint":false},{"pmid":"42074577","id":"PMC_42074577","title":"A Novel CFA3 Locus Encompassing KCNIP4 Is Associated with Idiopathic Epilepsy in Siberian Huskies.","date":"2026","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/42074577","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.11.03.621787","title":"Molecular Signatures of Resilience to Alzheimer’s Disease in Neocortical Layer 4 Neurons","date":"2024-11-04","source":"bioRxiv","url":"https://doi.org/10.1101/2024.11.03.621787","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.04.29.25326633","title":"Separating the genetics of disease, treatment and treatment response using graphical modeling and large-scale electronic health records","date":"2025-04-30","source":"bioRxiv","url":"https://doi.org/10.1101/2025.04.29.25326633","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.12.19.629410","title":"Genome-wide association analyses in dairy heifers highlight genes overlapping with mouse and human fertility and human health traits","date":"2024-12-21","source":"bioRxiv","url":"https://doi.org/10.1101/2024.12.19.629410","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":12166,"output_tokens":2529,"usd":0.037216,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9609,"output_tokens":3129,"usd":0.063135,"stage2_stop_reason":"end_turn"},"total_usd":0.100351,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"CALP/KChIP4 directly binds the C-terminal region of presenilin 2 (PS2) and co-localizes with PS2 in the endoplasmic reticulum upon co-expression in cultured cells. Overexpression of CALP did not affect PS complex metabolism/stability or gamma-cleavage of betaAPP or Notch site 3 cleavage.\",\n      \"method\": \"Co-immunoprecipitation, co-expression in cultured cells, co-localization imaging\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding and co-localization shown, but single lab with co-IP and imaging only; functional effect on PS complex was negative\",\n      \"pmids\": [\"11847232\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"CALP/KChIP4 directly binds voltage-gated potassium channel subunit Kv4.2 and, upon co-expression, reconstitutes A-type K+ current features, establishing CALP/KChIP4 as a functional component of native Kv4 channel complexes.\",\n      \"method\": \"Co-immunoprecipitation, co-expression electrophysiology (reconstitution of A-type K+ currents in cultured cells)\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct binding assay combined with functional reconstitution of A-type K+ current; replicated in subsequent studies\",\n      \"pmids\": [\"11847232\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"KChIP4 splice variant A (KChIP4A), but not splice variant B, slows Kv4 current inactivation to >100 ms when expressed in neurons. Cell-type-specific expression of KChIP4A (detected in globus pallidus and basal forebrain neurons but absent in striatal cholinergic interneurons and hippocampal CA1 pyramidal neurons by single-cell RT-PCR) correlates with the presence of a slowly inactivating component of A-type current.\",\n      \"method\": \"Single-cell RT-PCR in acutely dissociated rat neurons, Xenopus oocyte electrophysiology\",\n      \"journal\": \"The European journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — single-cell RT-PCR combined with electrophysiology, single lab, consistent mechanistic correlation\",\n      \"pmids\": [\"15233748\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The KChIP4 gene is regulated by at least two alternative promoters: a 325 bp fragment upstream of KChIP4.1 and an 818 bp fragment at the 5' end of KChIP4.4, both capable of driving reporter gene transcription in HT1080 cells and rat fetal brain neurons, and both contain CG islands but lack canonical TATA and CAAT boxes.\",\n      \"method\": \"Cloning and functional reporter gene assays (luciferase/reporter in HT1080 cells and primary neurons), RT-PCR identification of splice variants\",\n      \"journal\": \"Acta biochimica et biophysica Sinica\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional promoter assay in two cell types, single lab\",\n      \"pmids\": [\"15806290\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"CALP/KChIP4 binds directly to the cytoplasmic tail of GalT2 (UDP-Gal:GA2/GM2/GD2 beta-1,3-galactosyltransferase) in vitro and in CHO-K1 cells. Expression of CALP redistributes GalT2, SialT2, and GalNAcT from the Golgi to the ER, suggesting CALP/KChIP4 is involved in the trafficking of Golgi glycosyltransferases.\",\n      \"method\": \"Yeast two-hybrid, in vitro binding (immobilized recombinant CALP, peptide pulldown), co-immunoprecipitation in CHO-K1 cells, immunofluorescence localization\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal binding methods (yeast two-hybrid, in vitro pulldown, co-IP in mammalian cells) plus functional localization readout, single lab\",\n      \"pmids\": [\"18269347\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"KChIP2, KChIP3, and KChIP4 all co-immunoprecipitate with Kv4.2 in adult mouse posterior cortex. Simultaneous RNA interference-induced knockdown of KChIP2, KChIP3, and KChIP4 together markedly reduces I_A density and produces Kv current remodeling in cortical pyramidal neurons, demonstrating interdependent roles for these three KChIP subunits in Kv4-encoded I_A channel generation.\",\n      \"method\": \"Co-immunoprecipitation, RNA interference (siRNA/shRNA), whole-cell patch-clamp electrophysiology in cortical pyramidal neurons, genetic knockout mice (KChIP2-/-, KChIP3-/-)\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, genetic KO mouse models, and RNAi with direct electrophysiological readout; multiple orthogonal methods in single study\",\n      \"pmids\": [\"20943905\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"kcnip4 is a direct target of miR-3068-3p in rat cortical neurons; miR-3068-3p inhibition increases kcnip4 protein expression, enhances I_A (A-type K+ current) density, and protects against glutamate-induced excitotoxicity. Knockdown of kcnip4 by shRNA abolishes the neuroprotective effect of miR-3068-3p inhibition, and overexpression of kcnip4 alone is sufficient to confer neuroprotection, acting via upregulation of I_A.\",\n      \"method\": \"Luciferase reporter assay (miRNA target validation), western blot, shRNA knockdown, lentiviral overexpression, whole-cell patch-clamp electrophysiology, cell viability assays in rat primary cortical neurons\",\n      \"journal\": \"Journal of neurochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — luciferase target validation, shRNA KD, OE rescue, and electrophysiology; single lab with multiple orthogonal methods\",\n      \"pmids\": [\"31792968\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"A missense mutation (W→R) in a highly conserved region of KCNIP4 causes a dramatic reduction in KCNIP4 protein expression in the cerebellum of affected Norwegian Buhund dogs and is associated with progressive cerebellar ataxia, establishing an essential role for KCNIP4 in cerebellar Kv4 channel complex function.\",\n      \"method\": \"Whole-genome sequencing, Sanger sequencing genotyping, western blot, immunohistochemistry in cerebellar tissue, RT-PCR for transcript characterization\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function variant with protein expression confirmation by western blot and IHC, defined cerebellar phenotype; single study in a canine model\",\n      \"pmids\": [\"31999692\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"AAV-mediated overexpression of Kcnip4 in a humanized Alzheimer's disease mouse model reduced expression of activity-dependent genes Arc and c-Fos, suggesting that KCNIP4 acts as a compensatory mechanism against neuronal hyperexcitability in the context of AD pathology.\",\n      \"method\": \"AAV-mediated gene overexpression in humanized AD mouse model, gene expression analysis (Arc, c-Fos)\",\n      \"journal\": \"bioRxiv (preprint)\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single in vivo overexpression experiment in a preprint, no mechanistic dissection of pathway, single lab\",\n      \"pmids\": [\"bio_10.1101_2024.11.03.621787\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"KCNIP4 (CALP/KChIP4) is an EF-hand calcium-binding protein that functions as an accessory subunit of native neuronal Kv4 channel complexes by directly binding Kv4.2, modulating A-type K+ current kinetics (with splice variant KChIP4A specifically slowing inactivation), acting interdependently with KChIP2 and KChIP3 to generate cortical I_A; it also interacts with presenilin 2 at the ER (without affecting gamma-secretase activity), binds the cytoplasmic tail of Golgi glycosyltransferases to influence their trafficking, is post-transcriptionally regulated by miR-3068-3p, and loss-of-function mutations cause cerebellar ataxia in dogs.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"KCNIP4 (CALP/KChIP4) is an EF-hand-type accessory subunit of neuronal Kv4 voltage-gated potassium channel complexes that shapes the A-type K+ current (I_A) governing neuronal excitability [#1, #5]. It binds directly to Kv4.2 and, on co-expression, reconstitutes A-type K+ current features, establishing it as a functional component of native Kv4 complexes [#1]; in adult cortical pyramidal neurons KChIP4 acts interdependently with KChIP2 and KChIP3, all three co-assembling with Kv4.2, such that their simultaneous knockdown markedly reduces I_A density [#5]. The KChIP4A splice variant confers a distinctive slowing of Kv4 inactivation, and its cell-type-restricted expression correlates with a slowly inactivating I_A component in specific neuronal populations [#2]. Through its control of I_A, KCNIP4 sets neuroprotective tone: it is a direct target of miR-3068-3p, and relieving this repression raises KChIP4 protein and I_A density to protect cortical neurons from glutamate excitotoxicity [#6]. Beyond channel modulation, KCNIP4 has separable trafficking and protein-interaction roles: it binds the C-terminal region of presenilin 2 and co-localizes with it in the ER without affecting gamma-secretase activity [#0], and it binds the cytoplasmic tail of the Golgi glycosyltransferase GalT2 and redistributes Golgi glycosyltransferases to the ER [#4]. A loss-of-function missense mutation that depletes KCNIP4 protein in the cerebellum causes progressive cerebellar ataxia in dogs, demonstrating an essential in vivo role for the protein [#7].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Established the two principal molecular interactions of CALP/KChIP4 — defining it both as a Kv4 channel partner and as a presenilin 2-interacting ER protein — and distinguished a functional from a non-functional engagement.\",\n      \"evidence\": \"Co-immunoprecipitation, co-expression electrophysiology, and co-localization imaging in cultured cells\",\n      \"pmids\": [\"11847232\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis of Kv4.2 binding not resolved\",\n        \"Biological consequence of the PS2 interaction left unexplained given no effect on gamma-secretase\",\n        \"Calcium-dependence of these interactions not tested\"\n      ]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Resolved how splice diversity tunes channel kinetics by showing KChIP4A, but not variant B, slows Kv4 inactivation and that its restricted expression accounts for cell-type-specific slowly inactivating I_A.\",\n      \"evidence\": \"Single-cell RT-PCR in dissociated rat neurons combined with Xenopus oocyte electrophysiology\",\n      \"pmids\": [\"15233748\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Domain within KChIP4A responsible for slowed inactivation not mapped\",\n        \"Native confirmation in the implicated neuron types limited to expression correlation\"\n      ]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Clarified the transcriptional architecture of the locus by identifying two alternative promoters driving distinct splice variants, providing a basis for variant-specific expression.\",\n      \"evidence\": \"Reporter gene assays in HT1080 cells and primary neurons plus RT-PCR variant identification\",\n      \"pmids\": [\"15806290\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Trans-acting factors controlling each promoter not identified\",\n        \"Cell-type specificity of promoter usage not demonstrated in vivo\"\n      ]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Extended KCNIP4 function beyond ion channels by demonstrating direct binding to a Golgi glycosyltransferase cytoplasmic tail and a role in glycosyltransferase trafficking.\",\n      \"evidence\": \"Yeast two-hybrid, in vitro pulldown, co-IP in CHO-K1 cells, and immunofluorescence localization\",\n      \"pmids\": [\"18269347\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Physiological relevance of glycosyltransferase redistribution in neurons untested\",\n        \"Whether this role is calcium-regulated unknown\"\n      ]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Demonstrated that KChIP4 operates non-redundantly with KChIP2 and KChIP3 in native cortical neurons to generate Kv4-encoded I_A, moving from heterologous reconstitution to endogenous channel biology.\",\n      \"evidence\": \"Reciprocal Co-IP, triple RNAi knockdown, KChIP knockout mice, and whole-cell patch-clamp in cortical pyramidal neurons\",\n      \"pmids\": [\"20943905\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Individual contribution of KChIP4 alone not isolated by single knockdown\",\n        \"Stoichiometry of the multi-KChIP/Kv4.2 complex not defined\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Placed KCNIP4 in a post-transcriptional regulatory and neuroprotective pathway, showing that miR-3068-3p repression of kcnip4 controls I_A density and resistance to excitotoxicity.\",\n      \"evidence\": \"Luciferase target validation, shRNA knockdown, lentiviral overexpression rescue, and electrophysiology in rat cortical neurons\",\n      \"pmids\": [\"31792968\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"In vivo relevance of the miR-3068-3p/kcnip4 axis not tested\",\n        \"Downstream signaling linking I_A to excitotoxicity protection not dissected\"\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Provided in vivo genetic evidence that KCNIP4 is essential, with a loss-of-function mutation depleting cerebellar protein and causing progressive ataxia.\",\n      \"evidence\": \"Whole-genome and Sanger sequencing, western blot, and immunohistochemistry in affected Norwegian Buhund dogs\",\n      \"pmids\": [\"31999692\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanistic link between protein loss and cerebellar dysfunction at the channel level not directly demonstrated\",\n        \"Relevance to human ataxia not established\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Linked KCNIP4 to disease-relevant neuronal hyperexcitability, indicating it can dampen activity-dependent gene expression in an Alzheimer's disease context.\",\n      \"evidence\": \"AAV-mediated Kcnip4 overexpression in a humanized AD mouse model with Arc/c-Fos expression readout (preprint)\",\n      \"pmids\": [\"bio_10.1101_2024.11.03.621787\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Single overexpression experiment in a preprint, no mechanistic dissection\",\n        \"Whether the effect is mediated through Kv4/I_A not shown\",\n        \"No behavioral or pathological outcome measured\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How KCNIP4's calcium sensing, splice-variant-specific kinetic effects, and its non-channel roles in ER/Golgi trafficking are coordinated within neurons remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No structural model of the KCNIP4/Kv4 complex in the corpus\",\n        \"Calcium-dependence of KCNIP4 interactions not directly demonstrated\",\n        \"Relationship between channel-modulatory and trafficking functions unknown\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 2, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [0, 4]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1, 5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [1, 5]}\n    ],\n    \"complexes\": [\n      \"Kv4 channel complex\"\n    ],\n    \"partners\": [\n      \"KCND2\",\n      \"PSEN2\",\n      \"KCNIP2\",\n      \"KCNIP3\",\n      \"B3GALT4\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}