{"gene":"EPS15L1","run_date":"2026-04-28T17:46:03","timeline":{"discoveries":[{"year":1997,"finding":"Eps15R (EPS15L1) is an essential component of the endocytic machinery; microinjection of antibodies against Eps15R inhibits internalization of EGF and transferrin, demonstrating its required role in clathrin-mediated endocytosis.","method":"Antibody microinjection inhibition assay, endocytosis of EGF and transferrin","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 2 — direct functional loss-of-function experiment with defined phenotypic readout, replicated across multiple cargo types","pmids":["9407958"],"is_preprint":false},{"year":1995,"finding":"EPS15L1 (Eps15R) binds specifically to the amino-terminal SH3 domain of Crk via a conserved proline-rich motif (P-X-L-P-X-K), identifying it as a Crk SH3 domain binding partner.","method":"Expression library screen, co-precipitation, in vitro binding assay with defined motif mapping","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1/2 — direct in vitro binding with motif identification, replicated by co-precipitation from cell lysates","pmids":["7797522"],"is_preprint":false},{"year":1998,"finding":"EPS15L1 (Eps15R) localizes to plasma membrane clathrin-coated pits, associates in vivo with the coated pit adaptor protein AP-2, forms a complex with Eps15, and its EH domains have partially distinct binding specificities from those of Eps15.","method":"Immunoprecipitation, subcellular fractionation/localization, co-immunoprecipitation","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — reciprocal co-IP and direct localization with functional context, multiple orthogonal methods in one study","pmids":["9446614"],"is_preprint":false},{"year":2002,"finding":"The second ubiquitin-interacting motif (UIM) of EPS15L1 (Eps15R) is essential for its monoubiquitination; the UIM acts as a recruitment site for the ubiquitination machinery rather than serving as the ubiquitin acceptor site itself.","method":"Mutational analysis, ubiquitination assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1/2 — site-directed mutagenesis with functional ubiquitination readout, mechanistic dissection of UIM role","pmids":["12072436"],"is_preprint":false},{"year":2002,"finding":"Unlike Eps15 (which contains a leucine-rich nuclear export signal in its last ~25 amino acids that binds CRM1/exportin), EPS15L1 (Eps15R) lacks such a NES and therefore constitutively localizes to the nucleus; its nuclear localization is regulated by alternative splicing.","method":"Deletion mutagenesis, leptomycin B treatment, CRM1 binding assay, nuclear export assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (mutagenesis, drug treatment, direct binding assay) in a single study","pmids":["11777906"],"is_preprint":false},{"year":2016,"finding":"EPS15L1 (Eps15R) contains arrayed DPF motifs in its unstructured C-terminus that are differentially decoded by Fcho1/2 and AP-2; structural analysis reveals a spacing-dependent DPF triad bound by the Fcho1 μ-homology domain, forming transient Fcho1/2·Eps15/R·AP-2 ternary nanoclusters that facilitate AP-2 conformational activation and cargo binding during clathrin-coated vesicle formation.","method":"Crystal structure of Eps15R·Fcho1 μHD complex, cell-based assays with Eps15 sequestration/FCHO1/2 knockout, mutagenesis","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 1 — crystal structure plus mutagenesis plus cell-based epistasis, multiple orthogonal methods","pmids":["27237791"],"is_preprint":false},{"year":2017,"finding":"EPS15L1 (Eps15R), but not Eps15, is specifically required for clathrin-mediated trans-endocytosis of the EphB2-ephrinB1 complex and thereby controls EphB2-mediated cell repulsion; a novel DPFxxLDPF motif in Eps15R directly binds the clathrin terminal domain in vitro, and this clathrin-binding motif is required for cell repulsion rescue.","method":"siRNA knockdown, in vitro clathrin-binding assay, rescue experiment with clathrin-binding mutant, co-culture cell repulsion assay","journal":"Traffic (Copenhagen, Denmark)","confidence":"High","confidence_rationale":"Tier 2 — direct in vitro binding with motif mutagenesis, functional rescue experiment, loss-of-function with defined cellular phenotype","pmids":["28972287"],"is_preprint":false},{"year":2019,"finding":"EPS15L1 has a unique nonredundant role in the nervous system distinct from EPS15; both EPS15 and EPS15L1 redundantly regulate transferrin receptor endocytosis and iron homeostasis, and double knockout of both genes causes embryonic lethality in mice, while hematopoietic-specific double KO causes microcytic hypochromic anemia due to cell-autonomous defect in iron internalization.","method":"Constitutive and conditional knockout mice, transferrin receptor endocytosis assay, hematological analysis","journal":"Life science alliance","confidence":"High","confidence_rationale":"Tier 2 — clean KO/double KO with defined cellular and organismal phenotypes, multiple genetic models","pmids":["30692166"],"is_preprint":false},{"year":2012,"finding":"EPS15L1 (Eps15R) interacts with Smad proteins, is required for BMP signalling in Xenopus animal caps, stimulates Smad1 transcriptional activity, and antagonizes Smad2 signalling; these functions reside in the DPF-motif-enriched domain of Eps15R. In living cells, Eps15R segregates into spatially distinct regions with different Smads.","method":"Co-immunoprecipitation/interaction assay, Xenopus animal cap BMP signalling assay, transcriptional reporter assay, live cell imaging/compartmentalization","journal":"Open biology","confidence":"Medium","confidence_rationale":"Tier 2 — functional loss-of-function in Xenopus plus interaction assay plus reporter assay; single lab, moderate evidence","pmids":["22724065"],"is_preprint":false},{"year":2015,"finding":"eps15L1 is essential for T lymphocyte development in zebrafish; morpholino-mediated knockdown of eps15L1 mimics the T cell developmental defects seen in eps15L1 mutant embryos.","method":"Gene-breaking transposon mutagenesis, morpholino knockdown, flow cytometry, RT-PCR for T/B cell markers","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — genetic loss-of-function in zebrafish with defined T cell developmental phenotype, confirmed by orthogonal morpholino knockdown","pmids":["26161877"],"is_preprint":false}],"current_model":"EPS15L1 (Eps15R) is an endocytic accessory protein that constitutively localizes to clathrin-coated pits via its DPF motifs binding AP-2 and Fcho1/2, associates with the clathrin terminal domain via a DPFxxLDPF motif, is monoubiquitinated via its UIM, undergoes nuclear localization (regulated by alternative splicing, lacking the CRM1-dependent NES present in Eps15), redundantly cooperates with EPS15 to drive transferrin receptor endocytosis and iron homeostasis, uniquely mediates EphB2-ephrinB1 trans-endocytosis and cell repulsion, interacts with Smad proteins to modulate BMP signaling, and plays nonredundant roles in nervous system development and T lymphocyte development."},"narrative":{"teleology":[{"year":1995,"claim":"Identification of EPS15L1 as a Crk SH3-domain binding partner established it as a signaling-linked adaptor protein with a conserved proline-rich motif.","evidence":"Expression library screen and co-precipitation with Crk SH3 domain, with motif mapping","pmids":["7797522"],"confidence":"High","gaps":["Functional consequence of Crk–EPS15L1 interaction on signaling or endocytosis not determined","Whether this interaction occurs at endocytic sites in vivo was unknown"]},{"year":1997,"claim":"Demonstrating that antibodies against Eps15R block EGF and transferrin internalization established EPS15L1 as an essential component of clathrin-mediated endocytosis.","evidence":"Microinjection of anti-Eps15R antibodies with quantification of EGF and transferrin uptake","pmids":["9407958"],"confidence":"High","gaps":["Molecular mechanism by which EPS15L1 promotes endocytosis was unknown","Redundancy with EPS15 not addressed"]},{"year":1998,"claim":"Localization of EPS15L1 to clathrin-coated pits and demonstration of AP-2 and EPS15 complex formation placed it physically at the site of endocytic vesicle nucleation.","evidence":"Reciprocal co-immunoprecipitation and subcellular fractionation","pmids":["9446614"],"confidence":"High","gaps":["Which domains mediate AP-2 versus EPS15 binding was not resolved","Stoichiometry and dynamics of complexes at coated pits were unknown"]},{"year":2002,"claim":"Two mechanistic features distinguishing EPS15L1 from EPS15 were resolved: UIM-dependent monoubiquitination (the UIM recruits ubiquitination machinery rather than serving as the acceptor) and constitutive nuclear localization due to the absence of a CRM1-dependent NES, regulated by alternative splicing.","evidence":"Site-directed mutagenesis with ubiquitination assays; leptomycin B treatment and CRM1 binding assays with deletion constructs","pmids":["12072436","11777906"],"confidence":"High","gaps":["Nuclear function of EPS15L1 was unknown","Physiological signals regulating its ubiquitination state were not identified","Which splice variants control nuclear versus cytoplasmic distribution was not fully mapped"]},{"year":2012,"claim":"Discovery that EPS15L1 interacts with Smad proteins and modulates BMP signaling—stimulating Smad1 and antagonizing Smad2—revealed an unexpected signaling function beyond endocytosis, mediated by its DPF-motif domain.","evidence":"Co-immunoprecipitation, Xenopus animal cap BMP signaling assay, transcriptional reporter, live-cell imaging of Smad compartmentalization","pmids":["22724065"],"confidence":"Medium","gaps":["Mechanism by which EPS15L1 differentially regulates Smad1 versus Smad2 is unclear","Whether the Smad interaction occurs in the nucleus or at membranes was not resolved","Single-lab finding awaiting independent replication"]},{"year":2015,"claim":"Zebrafish genetic studies demonstrated a nonredundant requirement for eps15L1 in T lymphocyte development, extending its biological roles beyond endocytosis.","evidence":"Gene-breaking transposon mutagenesis and morpholino knockdown in zebrafish with T cell marker analysis","pmids":["26161877"],"confidence":"Medium","gaps":["Mechanism by which EPS15L1 controls T cell development (endocytic versus signaling) was not determined","Whether this role is conserved in mammals was unknown","Morpholino results require corroboration by stable genetic mutants with quantitative rescue"]},{"year":2016,"claim":"Structural resolution of how arrayed DPF motifs in EPS15L1 are differentially decoded by Fcho1/2 and AP-2 revealed the molecular basis for ternary nanocluster formation that drives AP-2 conformational activation at coated pits.","evidence":"Crystal structure of Eps15R·Fcho1 μHD complex, cell-based epistasis with Eps15 sequestration and FCHO1/2 knockout, mutagenesis","pmids":["27237791"],"confidence":"High","gaps":["Dynamics and stoichiometry of nanoclusters in living cells not fully resolved","Whether DPF-motif usage differs between EPS15 and EPS15L1 in vivo was not fully addressed"]},{"year":2017,"claim":"EPS15L1 was shown to be uniquely required (unlike EPS15) for EphB2–ephrinB1 trans-endocytosis and cell repulsion, mediated by a novel DPFxxLDPF clathrin-terminal-domain-binding motif, revealing a nonredundant endocytic function.","evidence":"siRNA knockdown, in vitro clathrin binding with motif mutagenesis, rescue experiments, co-culture repulsion assay","pmids":["28972287"],"confidence":"High","gaps":["How EPS15L1 is selectively recruited to EphB2-containing pits rather than bulk endocytic sites is unknown","Whether other receptor systems also rely specifically on EPS15L1 was not tested"]},{"year":2019,"claim":"Mouse knockout studies established that EPS15 and EPS15L1 are collectively essential for viability and transferrin receptor endocytosis/iron homeostasis, while EPS15L1 has a unique nervous-system role; hematopoietic double KO causes microcytic anemia from cell-autonomous iron internalization defects.","evidence":"Constitutive and conditional knockout mice, hematological analysis, transferrin receptor endocytosis assays","pmids":["30692166"],"confidence":"High","gaps":["Specific nervous system processes requiring EPS15L1 were not molecularly defined","Whether anemia phenotype reflects transferrin receptor surface retention or degradation was not fully dissected"]},{"year":null,"claim":"The mechanistic basis for EPS15L1's nonredundant roles in neural development and T lymphocyte development remains unresolved, as does whether its nuclear/Smad-signaling function operates independently of its endocytic role.","evidence":"","pmids":[],"confidence":"Low","gaps":["No neural-specific binding partners or cargoes identified for EPS15L1","Relationship between nuclear localization and BMP/Smad modulation versus endocytic function is mechanistically undefined","Whether EPS15L1's T cell role is conserved in mammals is untested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,2,5,6]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[2,5]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[2,5,6]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[4]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[0,2,5,6,7]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[6,8]}],"complexes":[],"partners":["EPS15","AP2A1","FCHO1","FCHO2","CLTC","CRK","SMAD1"],"other_free_text":[]},"mechanistic_narrative":"EPS15L1 (Eps15R) is an endocytic adaptor protein that functions at clathrin-coated pits to facilitate receptor internalization and has additional roles in BMP signaling and lymphocyte development. It localizes to clathrin-coated pits through DPF motifs that engage both Fcho1/2 and AP-2, forming transient ternary nanoclusters that activate AP-2 for cargo capture, and a distinct DPFxxLDPF motif mediates direct binding to the clathrin terminal domain [PMID:27237791, PMID:28972287]. EPS15L1 functions redundantly with EPS15 in transferrin receptor endocytosis and iron homeostasis—double knockout in mice is embryonically lethal and hematopoietic-specific double knockout causes microcytic anemia—yet EPS15L1 has unique, nonredundant roles in nervous system development, EphB2–ephrinB1 trans-endocytosis-dependent cell repulsion, and T lymphocyte development [PMID:30692166, PMID:28972287, PMID:26161877]. Unlike EPS15, EPS15L1 lacks a CRM1-dependent nuclear export signal and constitutively localizes to the nucleus in splice-form-dependent fashion, where it interacts with Smad proteins to stimulate BMP/Smad1 signaling and antagonize Smad2 signaling [PMID:11777906, PMID:22724065]."},"prefetch_data":{"uniprot":{"accession":"Q9UBC2","full_name":"Epidermal growth factor receptor substrate 15-like 1","aliases":["Eps15-related protein","Eps15R"],"length_aa":864,"mass_kda":94.3,"function":"Seems to be a constitutive component of clathrin-coated pits that is required for receptor-mediated endocytosis. Involved in endocytosis of integrin beta-1 (ITGB1) and transferrin receptor (TFR); internalization of ITGB1 as DAB2-dependent cargo but not TFR seems to require association with DAB2","subcellular_location":"Cell membrane; Nucleus; Membrane, coated pit","url":"https://www.uniprot.org/uniprotkb/Q9UBC2/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/EPS15L1","classification":"Not Classified","n_dependent_lines":13,"n_total_lines":1208,"dependency_fraction":0.01076158940397351},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"AP2B1","stoichiometry":10.0},{"gene":"EPS15","stoichiometry":10.0},{"gene":"AP2S1","stoichiometry":0.2},{"gene":"DEGS1","stoichiometry":0.2},{"gene":"ITSN1","stoichiometry":0.2},{"gene":"ITSN2","stoichiometry":0.2},{"gene":"NECAP2","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/EPS15L1","total_profiled":1310},"omim":[{"mim_id":"616826","title":"EPS15-LIKE PROTEIN 1; EPS15L1","url":"https://www.omim.org/entry/616826"},{"mim_id":"600051","title":"EPIDERMAL GROWTH FACTOR RECEPTOR PATHWAY SUBSTRATE 15; EPS15","url":"https://www.omim.org/entry/600051"},{"mim_id":"183600","title":"SPLIT-HAND/FOOT MALFORMATION 1; SHFM1","url":"https://www.omim.org/entry/183600"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Vesicles","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/EPS15L1"},"hgnc":{"alias_symbol":["eps15R"],"prev_symbol":[]},"alphafold":{"accession":"Q9UBC2","domains":[{"cath_id":"1.10.238.10","chopping":"10-94","consensus_level":"high","plddt":81.5512,"start":10,"end":94},{"cath_id":"1.10.238.10","chopping":"126-212","consensus_level":"high","plddt":82.3446,"start":126,"end":212},{"cath_id":"1.10.238.10","chopping":"274-347","consensus_level":"high","plddt":86.5636,"start":274,"end":347},{"cath_id":"1.20.5","chopping":"392-509","consensus_level":"medium","plddt":96.0791,"start":392,"end":509}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UBC2","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UBC2-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9UBC2-F1-predicted_aligned_error_v6.png","plddt_mean":65.81},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=EPS15L1","jax_strain_url":"https://www.jax.org/strain/search?query=EPS15L1"},"sequence":{"accession":"Q9UBC2","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9UBC2.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9UBC2/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9UBC2"}},"corpus_meta":[{"pmid":"9407958","id":"PMC_9407958","title":"eps15 and eps15R are essential components of the endocytic pathway.","date":"1997","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/9407958","citation_count":173,"is_preprint":false},{"pmid":"12072436","id":"PMC_12072436","title":"A ubiquitin-interacting motif (UIM) is essential for Eps15 and Eps15R ubiquitination.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12072436","citation_count":88,"is_preprint":false},{"pmid":"7797522","id":"PMC_7797522","title":"The SH3 domain of Crk binds specifically to a conserved proline-rich motif in Eps15 and Eps15R.","date":"1995","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/7797522","citation_count":87,"is_preprint":false},{"pmid":"27237791","id":"PMC_27237791","title":"Transient Fcho1/2⋅Eps15/R⋅AP-2 Nanoclusters Prime the AP-2 Clathrin Adaptor for Cargo Binding.","date":"2016","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/27237791","citation_count":83,"is_preprint":false},{"pmid":"9446614","id":"PMC_9446614","title":"Eps15R is a tyrosine kinase substrate with characteristics of a docking protein possibly involved in coated pits-mediated internalization.","date":"1998","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9446614","citation_count":69,"is_preprint":false},{"pmid":"11777906","id":"PMC_11777906","title":"Differential nucleocytoplasmic trafficking between the related endocytic proteins Eps15 and Eps15R.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/11777906","citation_count":35,"is_preprint":false},{"pmid":"18395097","id":"PMC_18395097","title":"EPS15R, TASP1, and PRPF3 are novel disease candidate genes targeted by HNF4alpha splice variants in hepatocellular carcinomas.","date":"2008","source":"Gastroenterology","url":"https://pubmed.ncbi.nlm.nih.gov/18395097","citation_count":28,"is_preprint":false},{"pmid":"29023680","id":"PMC_29023680","title":"First direct evidence of involvement of a homozygous loss-of-function variant in the EPS15L1 gene underlying split-hand/split-foot malformation.","date":"2018","source":"Clinical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/29023680","citation_count":20,"is_preprint":false},{"pmid":"28972287","id":"PMC_28972287","title":"Eps15R and clathrin regulate EphB2-mediated cell repulsion.","date":"2017","source":"Traffic (Copenhagen, Denmark)","url":"https://pubmed.ncbi.nlm.nih.gov/28972287","citation_count":17,"is_preprint":false},{"pmid":"30692166","id":"PMC_30692166","title":"Redundant and nonredundant organismal functions of EPS15 and EPS15L1.","date":"2019","source":"Life science alliance","url":"https://pubmed.ncbi.nlm.nih.gov/30692166","citation_count":14,"is_preprint":false},{"pmid":"26161877","id":"PMC_26161877","title":"Mutagenesis Screen Identifies agtpbp1 and eps15L1 as Essential for T lymphocyte Development in Zebrafish.","date":"2015","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/26161877","citation_count":13,"is_preprint":false},{"pmid":"21700002","id":"PMC_21700002","title":"A de novo 1.1Mb microdeletion of chromosome 19p13.11 provides indirect evidence for EPS15L1 to be a strong candidate for split hand split foot malformation.","date":"2011","source":"European journal of medical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/21700002","citation_count":12,"is_preprint":false},{"pmid":"35098448","id":"PMC_35098448","title":"LncRNA ABHD11-AS1 promotes tumor progression in papillary thyroid carcinoma by regulating EPS15L1/EGFR signaling pathway.","date":"2022","source":"Clinical & translational oncology : official publication of the Federation of Spanish Oncology Societies and of the National Cancer Institute of Mexico","url":"https://pubmed.ncbi.nlm.nih.gov/35098448","citation_count":10,"is_preprint":false},{"pmid":"10906484","id":"PMC_10906484","title":"Differential patterns of expression of Eps15 and Eps15R during mouse embryogenesis.","date":"2000","source":"Mechanisms of development","url":"https://pubmed.ncbi.nlm.nih.gov/10906484","citation_count":4,"is_preprint":false},{"pmid":"22724065","id":"PMC_22724065","title":"Eps15R is required for bone morphogenetic protein signalling and differentially compartmentalizes with Smad proteins.","date":"2012","source":"Open biology","url":"https://pubmed.ncbi.nlm.nih.gov/22724065","citation_count":3,"is_preprint":false},{"pmid":"41775633","id":"PMC_41775633","title":"Novel EPS15 :: KLF17 and EPS15L1 :: KLF17 Fusions Define a Distinctive Group of MUC4-Positive Spindled to Epithelioid Sarcomas.","date":"2026","source":"The American journal of surgical pathology","url":"https://pubmed.ncbi.nlm.nih.gov/41775633","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8561,"output_tokens":2387,"usd":0.030744},"stage2":{"model":"claude-opus-4-6","input_tokens":5712,"output_tokens":2622,"usd":0.141165},"total_usd":0.171909,"stage1_batch_id":"msgbatch_0118RScg3WGaGkaZRtWZbtce","stage2_batch_id":"msgbatch_01Cpfzvtbj42aqp5oYZ5Te2s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1997,\n      \"finding\": \"Eps15R (EPS15L1) is an essential component of the endocytic machinery; microinjection of antibodies against Eps15R inhibits internalization of EGF and transferrin, demonstrating its required role in clathrin-mediated endocytosis.\",\n      \"method\": \"Antibody microinjection inhibition assay, endocytosis of EGF and transferrin\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct functional loss-of-function experiment with defined phenotypic readout, replicated across multiple cargo types\",\n      \"pmids\": [\"9407958\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1995,\n      \"finding\": \"EPS15L1 (Eps15R) binds specifically to the amino-terminal SH3 domain of Crk via a conserved proline-rich motif (P-X-L-P-X-K), identifying it as a Crk SH3 domain binding partner.\",\n      \"method\": \"Expression library screen, co-precipitation, in vitro binding assay with defined motif mapping\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1/2 — direct in vitro binding with motif identification, replicated by co-precipitation from cell lysates\",\n      \"pmids\": [\"7797522\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"EPS15L1 (Eps15R) localizes to plasma membrane clathrin-coated pits, associates in vivo with the coated pit adaptor protein AP-2, forms a complex with Eps15, and its EH domains have partially distinct binding specificities from those of Eps15.\",\n      \"method\": \"Immunoprecipitation, subcellular fractionation/localization, co-immunoprecipitation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal co-IP and direct localization with functional context, multiple orthogonal methods in one study\",\n      \"pmids\": [\"9446614\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"The second ubiquitin-interacting motif (UIM) of EPS15L1 (Eps15R) is essential for its monoubiquitination; the UIM acts as a recruitment site for the ubiquitination machinery rather than serving as the ubiquitin acceptor site itself.\",\n      \"method\": \"Mutational analysis, ubiquitination assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1/2 — site-directed mutagenesis with functional ubiquitination readout, mechanistic dissection of UIM role\",\n      \"pmids\": [\"12072436\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Unlike Eps15 (which contains a leucine-rich nuclear export signal in its last ~25 amino acids that binds CRM1/exportin), EPS15L1 (Eps15R) lacks such a NES and therefore constitutively localizes to the nucleus; its nuclear localization is regulated by alternative splicing.\",\n      \"method\": \"Deletion mutagenesis, leptomycin B treatment, CRM1 binding assay, nuclear export assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (mutagenesis, drug treatment, direct binding assay) in a single study\",\n      \"pmids\": [\"11777906\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"EPS15L1 (Eps15R) contains arrayed DPF motifs in its unstructured C-terminus that are differentially decoded by Fcho1/2 and AP-2; structural analysis reveals a spacing-dependent DPF triad bound by the Fcho1 μ-homology domain, forming transient Fcho1/2·Eps15/R·AP-2 ternary nanoclusters that facilitate AP-2 conformational activation and cargo binding during clathrin-coated vesicle formation.\",\n      \"method\": \"Crystal structure of Eps15R·Fcho1 μHD complex, cell-based assays with Eps15 sequestration/FCHO1/2 knockout, mutagenesis\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure plus mutagenesis plus cell-based epistasis, multiple orthogonal methods\",\n      \"pmids\": [\"27237791\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"EPS15L1 (Eps15R), but not Eps15, is specifically required for clathrin-mediated trans-endocytosis of the EphB2-ephrinB1 complex and thereby controls EphB2-mediated cell repulsion; a novel DPFxxLDPF motif in Eps15R directly binds the clathrin terminal domain in vitro, and this clathrin-binding motif is required for cell repulsion rescue.\",\n      \"method\": \"siRNA knockdown, in vitro clathrin-binding assay, rescue experiment with clathrin-binding mutant, co-culture cell repulsion assay\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct in vitro binding with motif mutagenesis, functional rescue experiment, loss-of-function with defined cellular phenotype\",\n      \"pmids\": [\"28972287\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"EPS15L1 has a unique nonredundant role in the nervous system distinct from EPS15; both EPS15 and EPS15L1 redundantly regulate transferrin receptor endocytosis and iron homeostasis, and double knockout of both genes causes embryonic lethality in mice, while hematopoietic-specific double KO causes microcytic hypochromic anemia due to cell-autonomous defect in iron internalization.\",\n      \"method\": \"Constitutive and conditional knockout mice, transferrin receptor endocytosis assay, hematological analysis\",\n      \"journal\": \"Life science alliance\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO/double KO with defined cellular and organismal phenotypes, multiple genetic models\",\n      \"pmids\": [\"30692166\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"EPS15L1 (Eps15R) interacts with Smad proteins, is required for BMP signalling in Xenopus animal caps, stimulates Smad1 transcriptional activity, and antagonizes Smad2 signalling; these functions reside in the DPF-motif-enriched domain of Eps15R. In living cells, Eps15R segregates into spatially distinct regions with different Smads.\",\n      \"method\": \"Co-immunoprecipitation/interaction assay, Xenopus animal cap BMP signalling assay, transcriptional reporter assay, live cell imaging/compartmentalization\",\n      \"journal\": \"Open biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — functional loss-of-function in Xenopus plus interaction assay plus reporter assay; single lab, moderate evidence\",\n      \"pmids\": [\"22724065\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"eps15L1 is essential for T lymphocyte development in zebrafish; morpholino-mediated knockdown of eps15L1 mimics the T cell developmental defects seen in eps15L1 mutant embryos.\",\n      \"method\": \"Gene-breaking transposon mutagenesis, morpholino knockdown, flow cytometry, RT-PCR for T/B cell markers\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic loss-of-function in zebrafish with defined T cell developmental phenotype, confirmed by orthogonal morpholino knockdown\",\n      \"pmids\": [\"26161877\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"EPS15L1 (Eps15R) is an endocytic accessory protein that constitutively localizes to clathrin-coated pits via its DPF motifs binding AP-2 and Fcho1/2, associates with the clathrin terminal domain via a DPFxxLDPF motif, is monoubiquitinated via its UIM, undergoes nuclear localization (regulated by alternative splicing, lacking the CRM1-dependent NES present in Eps15), redundantly cooperates with EPS15 to drive transferrin receptor endocytosis and iron homeostasis, uniquely mediates EphB2-ephrinB1 trans-endocytosis and cell repulsion, interacts with Smad proteins to modulate BMP signaling, and plays nonredundant roles in nervous system development and T lymphocyte development.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"EPS15L1 (Eps15R) is an endocytic adaptor protein that functions at clathrin-coated pits to facilitate receptor internalization and has additional roles in BMP signaling and lymphocyte development. It localizes to clathrin-coated pits through DPF motifs that engage both Fcho1/2 and AP-2, forming transient ternary nanoclusters that activate AP-2 for cargo capture, and a distinct DPFxxLDPF motif mediates direct binding to the clathrin terminal domain [PMID:27237791, PMID:28972287]. EPS15L1 functions redundantly with EPS15 in transferrin receptor endocytosis and iron homeostasis—double knockout in mice is embryonically lethal and hematopoietic-specific double knockout causes microcytic anemia—yet EPS15L1 has unique, nonredundant roles in nervous system development, EphB2–ephrinB1 trans-endocytosis-dependent cell repulsion, and T lymphocyte development [PMID:30692166, PMID:28972287, PMID:26161877]. Unlike EPS15, EPS15L1 lacks a CRM1-dependent nuclear export signal and constitutively localizes to the nucleus in splice-form-dependent fashion, where it interacts with Smad proteins to stimulate BMP/Smad1 signaling and antagonize Smad2 signaling [PMID:11777906, PMID:22724065].\",\n  \"teleology\": [\n    {\n      \"year\": 1995,\n      \"claim\": \"Identification of EPS15L1 as a Crk SH3-domain binding partner established it as a signaling-linked adaptor protein with a conserved proline-rich motif.\",\n      \"evidence\": \"Expression library screen and co-precipitation with Crk SH3 domain, with motif mapping\",\n      \"pmids\": [\"7797522\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Functional consequence of Crk–EPS15L1 interaction on signaling or endocytosis not determined\",\n        \"Whether this interaction occurs at endocytic sites in vivo was unknown\"\n      ]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Demonstrating that antibodies against Eps15R block EGF and transferrin internalization established EPS15L1 as an essential component of clathrin-mediated endocytosis.\",\n      \"evidence\": \"Microinjection of anti-Eps15R antibodies with quantification of EGF and transferrin uptake\",\n      \"pmids\": [\"9407958\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Molecular mechanism by which EPS15L1 promotes endocytosis was unknown\",\n        \"Redundancy with EPS15 not addressed\"\n      ]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Localization of EPS15L1 to clathrin-coated pits and demonstration of AP-2 and EPS15 complex formation placed it physically at the site of endocytic vesicle nucleation.\",\n      \"evidence\": \"Reciprocal co-immunoprecipitation and subcellular fractionation\",\n      \"pmids\": [\"9446614\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Which domains mediate AP-2 versus EPS15 binding was not resolved\",\n        \"Stoichiometry and dynamics of complexes at coated pits were unknown\"\n      ]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Two mechanistic features distinguishing EPS15L1 from EPS15 were resolved: UIM-dependent monoubiquitination (the UIM recruits ubiquitination machinery rather than serving as the acceptor) and constitutive nuclear localization due to the absence of a CRM1-dependent NES, regulated by alternative splicing.\",\n      \"evidence\": \"Site-directed mutagenesis with ubiquitination assays; leptomycin B treatment and CRM1 binding assays with deletion constructs\",\n      \"pmids\": [\"12072436\", \"11777906\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Nuclear function of EPS15L1 was unknown\",\n        \"Physiological signals regulating its ubiquitination state were not identified\",\n        \"Which splice variants control nuclear versus cytoplasmic distribution was not fully mapped\"\n      ]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Discovery that EPS15L1 interacts with Smad proteins and modulates BMP signaling—stimulating Smad1 and antagonizing Smad2—revealed an unexpected signaling function beyond endocytosis, mediated by its DPF-motif domain.\",\n      \"evidence\": \"Co-immunoprecipitation, Xenopus animal cap BMP signaling assay, transcriptional reporter, live-cell imaging of Smad compartmentalization\",\n      \"pmids\": [\"22724065\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism by which EPS15L1 differentially regulates Smad1 versus Smad2 is unclear\",\n        \"Whether the Smad interaction occurs in the nucleus or at membranes was not resolved\",\n        \"Single-lab finding awaiting independent replication\"\n      ]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Zebrafish genetic studies demonstrated a nonredundant requirement for eps15L1 in T lymphocyte development, extending its biological roles beyond endocytosis.\",\n      \"evidence\": \"Gene-breaking transposon mutagenesis and morpholino knockdown in zebrafish with T cell marker analysis\",\n      \"pmids\": [\"26161877\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanism by which EPS15L1 controls T cell development (endocytic versus signaling) was not determined\",\n        \"Whether this role is conserved in mammals was unknown\",\n        \"Morpholino results require corroboration by stable genetic mutants with quantitative rescue\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Structural resolution of how arrayed DPF motifs in EPS15L1 are differentially decoded by Fcho1/2 and AP-2 revealed the molecular basis for ternary nanocluster formation that drives AP-2 conformational activation at coated pits.\",\n      \"evidence\": \"Crystal structure of Eps15R·Fcho1 μHD complex, cell-based epistasis with Eps15 sequestration and FCHO1/2 knockout, mutagenesis\",\n      \"pmids\": [\"27237791\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Dynamics and stoichiometry of nanoclusters in living cells not fully resolved\",\n        \"Whether DPF-motif usage differs between EPS15 and EPS15L1 in vivo was not fully addressed\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"EPS15L1 was shown to be uniquely required (unlike EPS15) for EphB2–ephrinB1 trans-endocytosis and cell repulsion, mediated by a novel DPFxxLDPF clathrin-terminal-domain-binding motif, revealing a nonredundant endocytic function.\",\n      \"evidence\": \"siRNA knockdown, in vitro clathrin binding with motif mutagenesis, rescue experiments, co-culture repulsion assay\",\n      \"pmids\": [\"28972287\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"How EPS15L1 is selectively recruited to EphB2-containing pits rather than bulk endocytic sites is unknown\",\n        \"Whether other receptor systems also rely specifically on EPS15L1 was not tested\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Mouse knockout studies established that EPS15 and EPS15L1 are collectively essential for viability and transferrin receptor endocytosis/iron homeostasis, while EPS15L1 has a unique nervous-system role; hematopoietic double KO causes microcytic anemia from cell-autonomous iron internalization defects.\",\n      \"evidence\": \"Constitutive and conditional knockout mice, hematological analysis, transferrin receptor endocytosis assays\",\n      \"pmids\": [\"30692166\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Specific nervous system processes requiring EPS15L1 were not molecularly defined\",\n        \"Whether anemia phenotype reflects transferrin receptor surface retention or degradation was not fully dissected\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The mechanistic basis for EPS15L1's nonredundant roles in neural development and T lymphocyte development remains unresolved, as does whether its nuclear/Smad-signaling function operates independently of its endocytic role.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No neural-specific binding partners or cargoes identified for EPS15L1\",\n        \"Relationship between nuclear localization and BMP/Smad modulation versus endocytic function is mechanistically undefined\",\n        \"Whether EPS15L1's T cell role is conserved in mammals is untested\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 2, 5, 6]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [2, 5]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [2, 5, 6]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [0, 2, 5, 6, 7]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [6, 8]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"EPS15\",\n      \"AP2A1\",\n      \"FCHO1\",\n      \"FCHO2\",\n      \"CLTC\",\n      \"CRK\",\n      \"SMAD1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}