{"gene":"IPCEF1","run_date":"2026-06-10T01:55:23","timeline":{"discoveries":[{"year":2003,"finding":"IPCEF1 binds cytohesin 2 via the C-terminal 121 amino acids of IPCEF1 and the coiled-coil domain of cytohesin 2, as determined by yeast two-hybrid, GST pull-down with deletion mutants, and co-immunoprecipitation in mammalian cells. IPCEF1 also interacts with other cytohesin family ARF GEFs, indicating conserved interaction across the family.","method":"Yeast two-hybrid screening, GST pull-down with deletion mutant analysis, co-immunoprecipitation in mammalian cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — multiple orthogonal methods (Y2H, GST pull-down with mutagenesis, co-IP) in a single focused study, domain mapping validated by deletion analysis","pmids":["12920129"],"is_preprint":false},{"year":2003,"finding":"In unstimulated cells IPCEF1 co-localizes with cytohesin 2 in the cytosol; upon EGF stimulation, IPCEF1 translocates to the plasma membrane via binding to cytohesin 2. A deletion mutant of IPCEF1 lacking the cytohesin 2-binding site fails to co-migrate to the membrane, demonstrating that membrane recruitment of IPCEF1 depends on its direct interaction with cytohesin 2.","method":"Immunofluorescence microscopy with wild-type and deletion-mutant IPCEF1 in EGF-stimulated mammalian cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct localization experiment with functional deletion mutant control, multiple methods in one rigorous study","pmids":["12920129"],"is_preprint":false},{"year":2003,"finding":"IPCEF1 increases cytohesin 2-stimulated ARF-GTP formation both in vitro and in vivo, demonstrating that IPCEF1 functions as a positive modulator of cytohesin 2 GEF activity toward ARF6.","method":"In vitro ARF-GTP formation assay and in vivo ARF6 activation assay in mammalian cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct biochemical assay (in vitro and in vivo GEF activity measurement) with functional outcome, single focused study with multiple methods","pmids":["12920129"],"is_preprint":false},{"year":2011,"finding":"IPCEF1 is the C-terminal half of a fused CNK3/IPCEF1 protein expressed in MDCK and CaCo-2 cells. Knockdown of this fused protein impairs HGF-induced Arf6 activation and cell migration, establishing that the CNK3-IPCEF1 fusion protein is required for HGF-dependent Arf6 activation.","method":"Identification of fused protein by molecular cloning/expression analysis; siRNA knockdown with Arf6 activation assay and migration assay in MDCK and CaCo-2 cells","journal":"Experimental cell research","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean knockdown with two orthogonal readouts (Arf6 activation + migration), in two cell lines, single lab","pmids":["22085542"],"is_preprint":false},{"year":2021,"finding":"Enforced expression of Ipcef1 in Th17 cells abolishes TLR2-dependent increases in migratory capacity and severely impairs the ability of Th17 cells to induce experimental autoimmune encephalomyelitis (EAE), identifying IPCEF1 as a regulator of Th17 cell migration downstream of TLR2 signaling.","method":"Retroviral enforced expression of Ipcef1 in Th17 cells; in vitro migration assay; in vivo EAE disease model","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — gain-of-function with two orthogonal phenotypic readouts (migration, EAE), single lab","pmids":["34192530"],"is_preprint":false},{"year":2009,"finding":"IPCEF1 mRNA is expressed in adult rat dorsal root ganglia (DRG), and peripheral nerve injury (spinal nerve ligation/transection or sciatic nerve transection) significantly upregulates IPCEF1 mRNA in injured DRGs, suggesting a role for IPCEF1 in nerve injury-induced membrane receptor trafficking in vivo.","method":"RT-PCR quantification of IPCEF1 mRNA in rat DRG following peripheral nerve injury models","journal":"Naunyn-Schmiedeberg's archives of pharmacology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single method (mRNA quantification), no functional experiment, single lab; mechanistic inference is correlative","pmids":["19756519"],"is_preprint":false}],"current_model":"IPCEF1 (also known as the C-terminal portion of the CNK3/IPCEF1 fusion protein) is a scaffold that binds the coiled-coil domain of cytohesin family ARF guanine nucleotide exchange factors through its C-terminal 121 amino acids, translocates with cytohesin 2 to the plasma membrane upon growth factor (EGF or HGF) stimulation, enhances cytohesin 2-mediated ARF6-GTP formation in vitro and in vivo, and is required for HGF-induced Arf6 activation and epithelial cell migration; in T cells, IPCEF1 also negatively regulates TLR2-driven Th17 cell migration and pathogenicity."},"narrative":{"mechanistic_narrative":"IPCEF1 is a scaffold protein that potentiates cytohesin-family ARF guanine nucleotide exchange factor signaling to drive ARF6-dependent membrane dynamics and cell migration [PMID:12920129, PMID:22085542]. It binds the coiled-coil domain of cytohesin 2 (and other cytohesin-family ARF GEFs) through its C-terminal 121 amino acids, and this direct interaction is required for IPCEF1 to translocate from the cytosol to the plasma membrane following EGF stimulation [PMID:12920129]. At the membrane, IPCEF1 acts as a positive modulator of cytohesin 2 GEF activity, enhancing ARF6-GTP formation both in vitro and in cells [PMID:12920129]. Consistent with this, the CNK3/IPCEF1 fusion protein expressed in epithelial cells is required for HGF-induced ARF6 activation and cell migration [PMID:22085542]. Beyond epithelial migration, IPCEF1 negatively regulates TLR2-dependent migratory capacity and pathogenicity of Th17 cells in an experimental autoimmune encephalomyelitis model [PMID:34192530].","teleology":[{"year":2003,"claim":"Established that IPCEF1 is a direct binding partner of cytohesin-family ARF GEFs, defining the physical interaction module that underlies its function.","evidence":"Yeast two-hybrid, GST pull-down with deletion mutants, and co-immunoprecipitation in mammalian cells mapping the IPCEF1 C-terminal 121 residues to the cytohesin 2 coiled-coil domain","pmids":["12920129"],"confidence":"High","gaps":["Does not define which cytohesin family members predominate in specific cell types","Structural basis of the C-terminus/coiled-coil interface not resolved"]},{"year":2003,"claim":"Showed that IPCEF1 membrane recruitment is signal-dependent and requires the cytohesin 2 interaction, connecting the binding event to spatial regulation.","evidence":"Immunofluorescence of wild-type vs. cytohesin-binding-deficient IPCEF1 in EGF-stimulated mammalian cells","pmids":["12920129"],"confidence":"High","gaps":["Mechanism linking EGF receptor activation to cytohesin 2 translocation not defined","Whether IPCEF1 recruits cytohesin or vice versa at the membrane is not disentangled"]},{"year":2003,"claim":"Demonstrated the functional consequence of the interaction: IPCEF1 enhances cytohesin 2 GEF output toward ARF6, establishing it as a positive modulator rather than a passive binder.","evidence":"In vitro ARF-GTP formation assay and in vivo ARF6 activation assay in mammalian cells","pmids":["12920129"],"confidence":"High","gaps":["Molecular basis of GEF stimulation (allosteric vs. localization effect) not resolved","Substrate selectivity among ARF isoforms not fully characterized"]},{"year":2011,"claim":"Placed IPCEF1 in a physiological signaling context by showing the CNK3/IPCEF1 fusion protein is required for HGF-induced ARF6 activation and epithelial migration.","evidence":"Molecular identification of the fusion protein plus siRNA knockdown with ARF6 activation and migration readouts in MDCK and CaCo-2 cells","pmids":["22085542"],"confidence":"High","gaps":["Contribution of the CNK3 portion vs. IPCEF1 portion not separated","Downstream effectors of ARF6 driving migration not identified"]},{"year":2021,"claim":"Extended IPCEF1 function to immune cells, identifying it as a negative regulator of TLR2-driven Th17 migration and autoimmune pathogenicity.","evidence":"Retroviral enforced expression of Ipcef1 in Th17 cells with in vitro migration assay and in vivo EAE model","pmids":["34192530"],"confidence":"Medium","gaps":["Whether the Th17 effect involves cytohesin/ARF6 signaling is not established","Loss-of-function evidence to complement gain-of-function is absent","Mechanism linking TLR2 to IPCEF1 not defined"]},{"year":2009,"claim":"Correlated IPCEF1 expression with peripheral nerve injury, raising a possible role in injury-associated receptor trafficking.","evidence":"RT-PCR quantification of IPCEF1 mRNA in rat DRG after nerve injury models","pmids":["19756519"],"confidence":"Low","gaps":["Correlative mRNA measurement only, no functional test","No link to cytohesin/ARF6 activity in neurons demonstrated"]},{"year":null,"claim":"How IPCEF1's scaffolding of cytohesin/ARF6 signaling integrates across distinct contexts (epithelial migration vs. Th17 immunity) and whether a single mechanism underlies its opposing migratory roles remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying mechanism connecting positive epithelial migration role to negative Th17 migration role","No structural model of the IPCEF1-cytohesin complex","Endogenous loss-of-function phenotypes largely uncharacterized"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1,2]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[2]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[1]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[1]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[2,3]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[3]}],"complexes":[],"partners":["CYTH2","ARF6","CNK3"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8WWN9","full_name":"Interactor protein for cytohesin exchange factors 1","aliases":["Phosphoinositide-binding protein PIP3-E"],"length_aa":437,"mass_kda":49.0,"function":"Enhances the promotion of guanine-nucleotide exchange by PSCD2 on ARF6 in a concentration-dependent manner","subcellular_location":"Cytoplasm; Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q8WWN9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/IPCEF1","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/IPCEF1","total_profiled":1310},"omim":[{"mim_id":"619948","title":"INTERACTION PROTEIN FOR CYTOHESIN EXCHANGE FACTORS 1; IPCEF1","url":"https://www.omim.org/entry/619948"},{"mim_id":"617476","title":"CNKSR FAMILY, MEMBER 3; CNKSR3","url":"https://www.omim.org/entry/617476"},{"mim_id":"612027","title":"TRAFFICKING REGULATOR AND SCAFFOLD PROTEIN TAMALIN; TAMALIN","url":"https://www.omim.org/entry/612027"},{"mim_id":"602488","title":"CYTOHESIN 2; CYTH2","url":"https://www.omim.org/entry/602488"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nuclear speckles","reliability":"Approved"},{"location":"Plasma membrane","reliability":"Approved"},{"location":"Nucleoli","reliability":"Additional"},{"location":"Cytoplasmic bodies","reliability":"Additional"}],"tissue_specificity":"Group enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"bone marrow","ntpm":15.8},{"tissue":"brain","ntpm":18.1},{"tissue":"lymphoid tissue","ntpm":12.6},{"tissue":"thyroid gland","ntpm":34.0}],"url":"https://www.proteinatlas.org/search/IPCEF1"},"hgnc":{"alias_symbol":["PIP3-E","KIAA0403"],"prev_symbol":[]},"alphafold":{"accession":"Q8WWN9","domains":[{"cath_id":"2.30.29.30","chopping":"31-141","consensus_level":"high","plddt":88.4663,"start":31,"end":141},{"cath_id":"-","chopping":"351-409","consensus_level":"high","plddt":88.6668,"start":351,"end":409}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8WWN9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8WWN9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8WWN9-F1-predicted_aligned_error_v6.png","plddt_mean":64.06},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=IPCEF1","jax_strain_url":"https://www.jax.org/strain/search?query=IPCEF1"},"sequence":{"accession":"Q8WWN9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8WWN9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8WWN9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8WWN9"}},"corpus_meta":[{"pmid":"26305897","id":"PMC_26305897","title":"Genome-Wide Association and Trans-ethnic Meta-Analysis for Advanced Diabetic Kidney Disease: Family Investigation of Nephropathy and Diabetes (FIND).","date":"2015","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/26305897","citation_count":108,"is_preprint":false},{"pmid":"12920129","id":"PMC_12920129","title":"Interaction protein for cytohesin exchange factors 1 (IPCEF1) binds cytohesin 2 and modifies its activity.","date":"2003","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12920129","citation_count":53,"is_preprint":false},{"pmid":"29679657","id":"PMC_29679657","title":"Eleven loci with new reproducible genetic associations with allergic disease risk.","date":"2018","source":"The Journal of allergy and clinical immunology","url":"https://pubmed.ncbi.nlm.nih.gov/29679657","citation_count":53,"is_preprint":false},{"pmid":"22085542","id":"PMC_22085542","title":"CNK3 and IPCEF1 produce a single protein that is required for HGF dependent Arf6 activation and migration.","date":"2011","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/22085542","citation_count":27,"is_preprint":false},{"pmid":"34545296","id":"PMC_34545296","title":"Oxidative Stress Genes in Diabetes Mellitus Type 2: Association with Diabetic Kidney Disease.","date":"2021","source":"Oxidative medicine and cellular longevity","url":"https://pubmed.ncbi.nlm.nih.gov/34545296","citation_count":23,"is_preprint":false},{"pmid":"34192530","id":"PMC_34192530","title":"Toll-like receptor 2 induces pathogenicity in Th17 cells and reveals a role for IPCEF in regulating Th17 cell migration.","date":"2021","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/34192530","citation_count":21,"is_preprint":false},{"pmid":"25863487","id":"PMC_25863487","title":"Somatic amplifications and deletions in genome of papillary thyroid carcinomas.","date":"2015","source":"Endocrine","url":"https://pubmed.ncbi.nlm.nih.gov/25863487","citation_count":21,"is_preprint":false},{"pmid":"19756519","id":"PMC_19756519","title":"Peripheral nerve injury up-regulates expression of interactor protein for cytohesin exchange factor 1 (IPCEF1) mRNA in rat dorsal root ganglion.","date":"2009","source":"Naunyn-Schmiedeberg's archives of pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/19756519","citation_count":12,"is_preprint":false},{"pmid":"34165176","id":"PMC_34165176","title":"Circular RNA profiling reveals a potential role of hsa_circ_IPCEF1 in papillary thyroid carcinoma.","date":"2021","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/34165176","citation_count":10,"is_preprint":false},{"pmid":"36465624","id":"PMC_36465624","title":"Screening and validation of lymph node metastasis risk-factor genes in papillary thyroid carcinoma.","date":"2022","source":"Frontiers in endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/36465624","citation_count":9,"is_preprint":false},{"pmid":"35634509","id":"PMC_35634509","title":"Construction of a Signature Model to Predict the Radioactive Iodine Response of Papillary Thyroid Cancer.","date":"2022","source":"Frontiers in endocrinology","url":"https://pubmed.ncbi.nlm.nih.gov/35634509","citation_count":4,"is_preprint":false},{"pmid":"39513122","id":"PMC_39513122","title":"IPCEF1: Expression Patterns, Clinical Correlates and New Target of Papillary Thyroid Carcinoma.","date":"2024","source":"Journal of Cancer","url":"https://pubmed.ncbi.nlm.nih.gov/39513122","citation_count":2,"is_preprint":false},{"pmid":"41937365","id":"PMC_41937365","title":"Placental DNA methylation mediates the prenatal maternal stress-childhood allergy association: A cohort study.","date":"2026","source":"Pediatric allergy and immunology : official publication of the European Society of Pediatric Allergy and Immunology","url":"https://pubmed.ncbi.nlm.nih.gov/41937365","citation_count":0,"is_preprint":false},{"pmid":"41661231","id":"PMC_41661231","title":"RNAseq-based meta-analyses revealed tumor suppressor-inducer fusion events in liver, oral, and ovarian cancer in the Indian population: a cancer cell surviving mechanism.","date":"2026","source":"Nucleosides, nucleotides & nucleic acids","url":"https://pubmed.ncbi.nlm.nih.gov/41661231","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9604,"output_tokens":1642,"usd":0.026721,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8390,"output_tokens":2326,"usd":0.05005,"stage2_stop_reason":"end_turn"},"total_usd":0.076771,"stage1_batch_id":"msgbatch_01DUPACZi7AAWwuZiUjseQF4","stage2_batch_id":"msgbatch_018yt7chE3f48PEFtDwtj6AE","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2003,\n      \"finding\": \"IPCEF1 binds cytohesin 2 via the C-terminal 121 amino acids of IPCEF1 and the coiled-coil domain of cytohesin 2, as determined by yeast two-hybrid, GST pull-down with deletion mutants, and co-immunoprecipitation in mammalian cells. IPCEF1 also interacts with other cytohesin family ARF GEFs, indicating conserved interaction across the family.\",\n      \"method\": \"Yeast two-hybrid screening, GST pull-down with deletion mutant analysis, co-immunoprecipitation in mammalian cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — multiple orthogonal methods (Y2H, GST pull-down with mutagenesis, co-IP) in a single focused study, domain mapping validated by deletion analysis\",\n      \"pmids\": [\"12920129\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"In unstimulated cells IPCEF1 co-localizes with cytohesin 2 in the cytosol; upon EGF stimulation, IPCEF1 translocates to the plasma membrane via binding to cytohesin 2. A deletion mutant of IPCEF1 lacking the cytohesin 2-binding site fails to co-migrate to the membrane, demonstrating that membrane recruitment of IPCEF1 depends on its direct interaction with cytohesin 2.\",\n      \"method\": \"Immunofluorescence microscopy with wild-type and deletion-mutant IPCEF1 in EGF-stimulated mammalian cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct localization experiment with functional deletion mutant control, multiple methods in one rigorous study\",\n      \"pmids\": [\"12920129\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"IPCEF1 increases cytohesin 2-stimulated ARF-GTP formation both in vitro and in vivo, demonstrating that IPCEF1 functions as a positive modulator of cytohesin 2 GEF activity toward ARF6.\",\n      \"method\": \"In vitro ARF-GTP formation assay and in vivo ARF6 activation assay in mammalian cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct biochemical assay (in vitro and in vivo GEF activity measurement) with functional outcome, single focused study with multiple methods\",\n      \"pmids\": [\"12920129\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"IPCEF1 is the C-terminal half of a fused CNK3/IPCEF1 protein expressed in MDCK and CaCo-2 cells. Knockdown of this fused protein impairs HGF-induced Arf6 activation and cell migration, establishing that the CNK3-IPCEF1 fusion protein is required for HGF-dependent Arf6 activation.\",\n      \"method\": \"Identification of fused protein by molecular cloning/expression analysis; siRNA knockdown with Arf6 activation assay and migration assay in MDCK and CaCo-2 cells\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean knockdown with two orthogonal readouts (Arf6 activation + migration), in two cell lines, single lab\",\n      \"pmids\": [\"22085542\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Enforced expression of Ipcef1 in Th17 cells abolishes TLR2-dependent increases in migratory capacity and severely impairs the ability of Th17 cells to induce experimental autoimmune encephalomyelitis (EAE), identifying IPCEF1 as a regulator of Th17 cell migration downstream of TLR2 signaling.\",\n      \"method\": \"Retroviral enforced expression of Ipcef1 in Th17 cells; in vitro migration assay; in vivo EAE disease model\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — gain-of-function with two orthogonal phenotypic readouts (migration, EAE), single lab\",\n      \"pmids\": [\"34192530\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"IPCEF1 mRNA is expressed in adult rat dorsal root ganglia (DRG), and peripheral nerve injury (spinal nerve ligation/transection or sciatic nerve transection) significantly upregulates IPCEF1 mRNA in injured DRGs, suggesting a role for IPCEF1 in nerve injury-induced membrane receptor trafficking in vivo.\",\n      \"method\": \"RT-PCR quantification of IPCEF1 mRNA in rat DRG following peripheral nerve injury models\",\n      \"journal\": \"Naunyn-Schmiedeberg's archives of pharmacology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single method (mRNA quantification), no functional experiment, single lab; mechanistic inference is correlative\",\n      \"pmids\": [\"19756519\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"IPCEF1 (also known as the C-terminal portion of the CNK3/IPCEF1 fusion protein) is a scaffold that binds the coiled-coil domain of cytohesin family ARF guanine nucleotide exchange factors through its C-terminal 121 amino acids, translocates with cytohesin 2 to the plasma membrane upon growth factor (EGF or HGF) stimulation, enhances cytohesin 2-mediated ARF6-GTP formation in vitro and in vivo, and is required for HGF-induced Arf6 activation and epithelial cell migration; in T cells, IPCEF1 also negatively regulates TLR2-driven Th17 cell migration and pathogenicity.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"IPCEF1 is a scaffold protein that potentiates cytohesin-family ARF guanine nucleotide exchange factor signaling to drive ARF6-dependent membrane dynamics and cell migration [#0, #2, #3]. It binds the coiled-coil domain of cytohesin 2 (and other cytohesin-family ARF GEFs) through its C-terminal 121 amino acids, and this direct interaction is required for IPCEF1 to translocate from the cytosol to the plasma membrane following EGF stimulation [#0, #1]. At the membrane, IPCEF1 acts as a positive modulator of cytohesin 2 GEF activity, enhancing ARF6-GTP formation both in vitro and in cells [#2]. Consistent with this, the CNK3/IPCEF1 fusion protein expressed in epithelial cells is required for HGF-induced ARF6 activation and cell migration [#3]. Beyond epithelial migration, IPCEF1 negatively regulates TLR2-dependent migratory capacity and pathogenicity of Th17 cells in an experimental autoimmune encephalomyelitis model [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Established that IPCEF1 is a direct binding partner of cytohesin-family ARF GEFs, defining the physical interaction module that underlies its function.\",\n      \"evidence\": \"Yeast two-hybrid, GST pull-down with deletion mutants, and co-immunoprecipitation in mammalian cells mapping the IPCEF1 C-terminal 121 residues to the cytohesin 2 coiled-coil domain\",\n      \"pmids\": [\"12920129\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not define which cytohesin family members predominate in specific cell types\", \"Structural basis of the C-terminus/coiled-coil interface not resolved\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Showed that IPCEF1 membrane recruitment is signal-dependent and requires the cytohesin 2 interaction, connecting the binding event to spatial regulation.\",\n      \"evidence\": \"Immunofluorescence of wild-type vs. cytohesin-binding-deficient IPCEF1 in EGF-stimulated mammalian cells\",\n      \"pmids\": [\"12920129\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking EGF receptor activation to cytohesin 2 translocation not defined\", \"Whether IPCEF1 recruits cytohesin or vice versa at the membrane is not disentangled\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Demonstrated the functional consequence of the interaction: IPCEF1 enhances cytohesin 2 GEF output toward ARF6, establishing it as a positive modulator rather than a passive binder.\",\n      \"evidence\": \"In vitro ARF-GTP formation assay and in vivo ARF6 activation assay in mammalian cells\",\n      \"pmids\": [\"12920129\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of GEF stimulation (allosteric vs. localization effect) not resolved\", \"Substrate selectivity among ARF isoforms not fully characterized\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Placed IPCEF1 in a physiological signaling context by showing the CNK3/IPCEF1 fusion protein is required for HGF-induced ARF6 activation and epithelial migration.\",\n      \"evidence\": \"Molecular identification of the fusion protein plus siRNA knockdown with ARF6 activation and migration readouts in MDCK and CaCo-2 cells\",\n      \"pmids\": [\"22085542\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Contribution of the CNK3 portion vs. IPCEF1 portion not separated\", \"Downstream effectors of ARF6 driving migration not identified\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Extended IPCEF1 function to immune cells, identifying it as a negative regulator of TLR2-driven Th17 migration and autoimmune pathogenicity.\",\n      \"evidence\": \"Retroviral enforced expression of Ipcef1 in Th17 cells with in vitro migration assay and in vivo EAE model\",\n      \"pmids\": [\"34192530\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether the Th17 effect involves cytohesin/ARF6 signaling is not established\", \"Loss-of-function evidence to complement gain-of-function is absent\", \"Mechanism linking TLR2 to IPCEF1 not defined\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Correlated IPCEF1 expression with peripheral nerve injury, raising a possible role in injury-associated receptor trafficking.\",\n      \"evidence\": \"RT-PCR quantification of IPCEF1 mRNA in rat DRG after nerve injury models\",\n      \"pmids\": [\"19756519\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Correlative mRNA measurement only, no functional test\", \"No link to cytohesin/ARF6 activity in neurons demonstrated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How IPCEF1's scaffolding of cytohesin/ARF6 signaling integrates across distinct contexts (epithelial migration vs. Th17 immunity) and whether a single mechanism underlies its opposing migratory roles remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying mechanism connecting positive epithelial migration role to negative Th17 migration role\", \"No structural model of the IPCEF1-cytohesin complex\", \"Endogenous loss-of-function phenotypes largely uncharacterized\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2, 3]},\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"CYTH2\", \"ARF6\", \"CNK3\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}