{"gene":"ECPAS","run_date":"2026-06-09T23:54:42","timeline":{"discoveries":[{"year":2004,"finding":"Mammalian Ecm29 is present exclusively on 26S proteasomes in HeLa cells and localizes to the centrosome and a subset of secretory compartments including endosomes, the ER, and the ERGIC, as determined by confocal immunofluorescence microscopy and glycerol-gradient fractionation. Ecm29 is up-regulated 2–3-fold in toxin-resistant CHO cells with increased ER-associated degradation, suggesting it couples 26S proteasomes to secretory compartments engaged in quality control.","method":"Antibody generation, glycerol-gradient fractionation, confocal immunofluorescence microscopy, CHO mutant cell line analysis","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization by confocal microscopy with functional correlation in mutant CHO cells, single lab, two orthogonal methods","pmids":["15496406"],"is_preprint":false},{"year":2010,"finding":"Ecm29 controls the integrity of RP-CP (regulatory particle–core particle) assemblies in yeast, recognizing RP-CP species in which CP maturation is stalled due to the lack of distinct beta subunits. Reconstitution assays demonstrated that Ecm29 functions as a scaffold protein during remodeling of incompletely matured RP-CP assemblies into regular enzymes, and is degraded upon completion of CP maturation.","method":"Yeast genetics, proteasome reconstitution assays, biochemical fractionation","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution assays with genetic validation, single lab with multiple orthogonal methods","pmids":["20620957"],"is_preprint":false},{"year":2010,"finding":"The C-terminal half of human Ecm29 binds myosins and kinesins (molecular motors), while the N-terminal region binds endocytic proteins Vps11, Rab11-FIP4, and rabaptin. A central fragment of Ecm29 is sufficient for 26S proteasome binding. Ecm29-26S proteasomes are present on flotillin-positive endosomes but absent from caveolin- and clathrin-decorated endosomes. Expression of the central fragment reduces proteasome association with flotillin-positive endosomes.","method":"Genome-wide two-hybrid screens, mass spectrometry, confocal microscopy, glycerol-gradient fractionation, domain mapping with truncation constructs","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal two-hybrid and MS identification of interactors, domain-mapped binding, and confocal functional assay in single lab with multiple orthogonal methods","pmids":["20682791"],"is_preprint":false},{"year":2011,"finding":"Not4 E3 ligase associates with the regulatory particle (RP) of the proteasome holoenzyme and interacts with Ecm29. In the absence of Not4, Ecm29 interacts less well with the proteasome, becomes ubiquitinated and degraded. This indicates that appropriate Ecm29-proteasome interaction requires Not4, establishing Ecm29 as a proteasome chaperone whose stability depends on Not4-mediated regulation.","method":"Yeast genetics (deletion strains), co-immunoprecipitation, ubiquitination assay, proteasome purification and activity assays","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP and genetic epistasis in yeast, single lab, multiple methods","pmids":["21321079"],"is_preprint":false},{"year":2011,"finding":"Ecm29 is enriched on proteasomes purified from Saccharomyces cerevisiae rpt5-Δ3 strains (faulty proteasomes), and these Ecm29-containing proteasomes have reduced suc-LLVY-AMC hydrolytic activity. Deletion of ECM29 rescues phenotypes of rpt5-Δ3 and nas2Δ in an hsm3Δ background, establishing Ecm29 as a negative regulator/inhibitor that recognizes and inhibits aberrant proteasomes.","method":"Yeast genetics (deletion strains, epistasis analysis), proteasome purification, peptidase activity assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis combined with biochemical activity assay, single lab","pmids":["21878651"],"is_preprint":false},{"year":2013,"finding":"Ecm29 inhibits proteasomal ATPase activity and induces a closed conformation of the substrate entry channel of the 20S core particle. Besides inhibiting peptide substrate cleavage in vitro, Ecm29 inhibits degradation of ubiquitin-dependent and -independent substrates in vivo. Chemical cross-linking identified that Ecm29 binds to or in close proximity to proteasomal ATPase subunit Rpt5. Ecm29 preferentially associates with mutant and nucleotide-depleted proteasomes.","method":"In vitro peptidase and ATPase activity assays, in vivo ubiquitin-dependent substrate degradation assays, chemical cross-linking mass spectrometry, electron microscopy (gate conformation)","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro enzymatic assays with cross-linking MS mapping of interaction site and in vivo substrate degradation, single lab with multiple orthogonal methods","pmids":["23995839"],"is_preprint":false},{"year":2013,"finding":"Depletion of Ecm29 increases abundance of TLR3 and increases levels of LC3β and p62 (autophagy mediators). Loss of Ecm29 enhances TLR3 signaling, characterized by increased TRAF3 levels, increased phosphorylation of effector kinases, increased nuclear localization of IRF3, and accumulation of signaling molecules at juxtanuclear recycling endosomes. This establishes that Ecm29-associated proteasomes play a role in mediating autophagy and attenuation of TLR3-dependent signaling.","method":"siRNA depletion of Ecm29 in HEK-293 and HeLa cells, immunoblotting, immunofluorescence microscopy","journal":"Science signaling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — knockdown with multiple pathway readouts, single lab","pmids":["24084648"],"is_preprint":false},{"year":2016,"finding":"Yeast Ecm29 requires the phosphorylated C-terminal tail of the proteasome α7 subunit for its association with the proteasome. This represents the first example of phosphorylation-dependent binding of a proteasome regulatory factor. The ability of Ecm29 to bind mutant proteasomes requires both the α7-tail phosphorylation-dependent binding site and a previously identified Rpt5 binding site; the need for two binding sites on different subcomplexes explains the specificity of Ecm29 for proteasome holoenzymes.","method":"Yeast genetics (α7 tail phosphorylation mutants), co-immunoprecipitation/pulldown, proteasome purification","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic and biochemical demonstration of phospho-dependent binding, single lab, two complementary mutant approaches","pmids":["27302526"],"is_preprint":false},{"year":2016,"finding":"KIAA0368-deficient (Ecm29 knockout) mice show normal peptidase activity and proteasome formation under basal conditions, but fail to dissociate 26S proteasomes under oxidative stress conditions where wild-type cells dissociate 26S proteasomes. This correlates with reduced degradation of damaged proteins and increased resistance to oxidative stress in KIAA0368-deficient cells, establishing Ecm29 as required for 26S proteasome dissociation under stress.","method":"KIAA0368-deficient mouse generation, native gel proteasome analysis, peptidase activity assays, oxidative stress challenge","journal":"Journal of biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockout mouse model with biochemical proteasome analysis, single lab","pmids":["26802743"],"is_preprint":false},{"year":2017,"finding":"Human Ecm29 is the main proteasome-interacting protein responsible for stress-triggered (H2O2) disassembly of the 26S proteasome. Cross-linking mass spectrometry mapped Ecm29 interactions within itself and with proteasome subunits; integrative structural modeling proposed that Ecm29 intrudes on the interaction between the 20S core particle and the 19S regulatory particle, disrupting proteasome structure in response to oxidative stress. Stress-induced 26S disassembly is conserved from yeast to human.","method":"XAP (in vivo cross-linking-assisted affinity purification) with SILAC quantitative MS, disuccinimidyl sulfoxide cross-linking MS, integrative structural modeling","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — cross-linking MS with quantitative proteomics, structural modeling, conservation across species, multiple orthogonal methods","pmids":["28821611"],"is_preprint":false},{"year":2020,"finding":"Ecm29 mediates proteasome distribution to the axon initial segment (AIS) through interaction with the AIS scaffold protein ankyrin G; both the Ecm29 N-terminal domain and an intact AIS structure are required for transport and tethering of proteasomes in the AIS region. Ecm29 knockout in neurons increases NKCC1 protein density in the AIS, delays the GABAergic response switch, and increases action potential firing frequency at early postnatal ages. Ecm29 KO neurons show accelerated AIS developmental positioning, rescued by ectopic Ecm29 expression or NKCC1 inhibition.","method":"Ecm29 knockout mouse, confocal and live imaging, domain deletion constructs, electrophysiology, chemical convulsive seizure assay, rescue experiments","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with multiple cellular and physiological readouts, domain-mapped mechanism, rescue experiments, multiple orthogonal methods","pmids":["31910261"],"is_preprint":false},{"year":2021,"finding":"Ecm29 regulates proteasome distribution between the centrosome and cell cortex in B cells. Silencing Ecm29 shifts the proteasome from the centrosome to the cell cortex and immunological synapse (IS), resulting in increased F-actin at the centrosome, impaired centrosome and lysosome repositioning to the IS, defective antigen extraction and presentation, decreased actin retrograde flow in lamellipodia, and enhanced spreading. This establishes that Ecm29-controlled asymmetric proteasome distribution coordinates actin dynamics at the centrosome and IS.","method":"siRNA silencing of Ecm29 in B cells, confocal microscopy, actin dynamics measurement, antigen extraction and presentation assays","journal":"Frontiers in cell and developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — knockdown with multiple cellular readouts (localization, actin, antigen presentation), single lab","pmids":["34055780"],"is_preprint":false},{"year":2023,"finding":"ECPAS mediates 26S proteasome disassembly into 20S and 19S subcomplexes in response to glucose starvation. Loss of ECPAS abrogates 26S dissociation and reduces degradation of 20S proteasome substrates including puromycylated polypeptides. In silico modeling suggests ECPAS conformational changes initiate the disassembly process. ECPAS is also essential for ER stress response and cell survival during glucose starvation. Elevated 20S proteasome levels are found in glucose-deprived tumors in vivo in a xenograft model.","method":"ECPAS KO cells, subcomplex affinity purification, quantitative mass spectrometry, in silico structural modeling, xenograft mouse model, puromycylated polypeptide degradation assay","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO with quantitative proteomics, structural modeling, in vivo xenograft, multiple orthogonal methods, independent replication supported by prior oxidative stress work","pmids":["37384533"],"is_preprint":false},{"year":2023,"finding":"PA200 and ECPAS work cooperatively during spermatogenesis; double knockout (dKO) mice are infertile with considerably reduced proteasome activity in testes and epididymides. In epididymal sperm, ECPAS localizes to the acrosome. Mass spectrometric analysis identified LPIN1 as a target protein for both PA200 and ECPAS (confirmed by immunoblotting and immunostaining). dKO sperm display disorganization of the mitochondrial sheath.","method":"Double-knockout mouse generation, mass spectrometry, immunoblotting, immunostaining, ultrastructural analysis, proteasome activity assay","journal":"Biomolecules","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with MS substrate identification and multiple validation methods, single lab","pmids":["37189334"],"is_preprint":false},{"year":2025,"finding":"Loss of Ecm29 in oligodendroglia or microglia (inducible conditional KO) increases susceptibility to experimental autoimmune encephalomyelitis (EAE) and reduces regulatory T cell populations in the spinal cord. Immunopeptidome profiling identified self-antigens (including NDUFA1p) whose generation fidelity depends on Ecm29/proteasome function, and intraspinal AAV-mediated expression of NDUFA1p ameliorates EAE and expands NDUFA1p-recognizing CD103+CD8+CD122+ Treg cells, establishing that Ecm29-controlled proteasome activity governs CNS immune tolerance through neuroglial antigen generation.","method":"Inducible conditional Ecm29 KO mice, EAE model, immunopeptidome profiling (MS), AAV-mediated antigen expression, flow cytometry","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — conditional genetic KO with immunopeptidome MS and in vivo rescue, single lab, multiple methods","pmids":["39786996"],"is_preprint":false}],"current_model":"ECPAS/Ecm29 is a large HEAT-repeat scaffold protein that associates with 26S proteasomes as an adaptor and quality-control factor: it recognizes aberrant or incompletely assembled proteasomes (via dual binding sites on α7-phospho tail and Rpt5 of the 19S), inhibits proteasomal ATPase activity and substrate entry by inducing gate closure, and drives 26S-to-20S/19S disassembly in response to stress signals (oxidative stress, glucose starvation) by intruding between the 20S and 19S subcomplexes; additionally, Ecm29 acts as a subcellular adaptor that tethers proteasomes to flotillin-positive endosomes (via motor protein and endocytic protein interactions), to the axon initial segment (via ankyrin G), and to the centrosome of immune cells, thereby spatially coordinating proteolysis with processes including secretory-pathway quality control, neuronal maturation (GABA switch), cytoskeletal remodeling at the immune synapse, spermatogenesis, and CNS immune tolerance through neuroglial antigen generation."},"narrative":{"mechanistic_narrative":"ECPAS (Ecm29) is a large HEAT-repeat scaffold protein that associates with the 26S proteasome as a quality-control and adaptor factor, coupling proteolysis to proteasome integrity surveillance, stress responses, and subcellular targeting [PMID:15496406, PMID:20682791]. It functions as a proteasome chaperone that monitors regulatory particle–core particle (RP-CP) assembly, recognizing stalled or aberrant assemblies and remodeling them into mature enzymes [PMID:20620957]. ECPAS preferentially associates with mutant and nucleotide-depleted proteasomes through dual binding sites—the phosphorylated C-terminal tail of the α7 core subunit and the Rpt5 ATPase of the 19S regulatory particle—a requirement for two sites on different subcomplexes that explains its specificity for holoenzymes and aberrant species [PMID:21878651, PMID:23995839, PMID:27302526]. Engagement of aberrant proteasomes inhibits ATPase activity and induces closure of the 20S substrate-entry gate, blocking degradation of ubiquitin-dependent and -independent substrates [PMID:23995839]. Under stress—oxidative stress or glucose starvation—ECPAS is the principal driver of 26S disassembly into 20S and 19S subcomplexes, intruding on the 20S–19S interface, a function conserved from yeast to human [PMID:26802743, PMID:28821611, PMID:37384533]. Beyond holoenzyme regulation, ECPAS acts as a subcellular adaptor: its C-terminal half binds molecular motors (myosins, kinesins) and its N-terminal region binds endocytic proteins, tethering proteasomes to flotillin-positive endosomes [PMID:20682791], to the axon initial segment via ankyrin G where it controls NKCC1 levels and the GABAergic developmental switch [PMID:31910261], and to the centrosome of B cells to coordinate proteasome distribution with actin dynamics at the immune synapse [PMID:34055780]. ECPAS additionally cooperates with PA200 during spermatogenesis, targeting LPIN1 and supporting mitochondrial sheath organization [PMID:37189334], and governs CNS immune tolerance through fidelity of neuroglial self-antigen generation [PMID:39786996].","teleology":[{"year":2004,"claim":"Established that mammalian Ecm29 is a dedicated 26S proteasome partner with a non-uniform subcellular distribution, raising the possibility that it couples proteolysis to specific compartments.","evidence":"Glycerol-gradient fractionation and confocal immunofluorescence in HeLa and toxin-resistant CHO cells","pmids":["15496406"],"confidence":"Medium","gaps":["Functional role at the centrosome/secretory compartments not defined","No molecular mechanism for targeting","Correlative link to ERAD only"]},{"year":2010,"claim":"Defined Ecm29 as a scaffold/chaperone for proteasome biogenesis, answering whether it acts on assembled enzymes versus assembly intermediates.","evidence":"Yeast genetics and proteasome reconstitution assays of stalled RP-CP species","pmids":["20620957"],"confidence":"High","gaps":["Structural basis of intermediate recognition not resolved","Trigger for Ecm29 degradation upon maturation not detailed"]},{"year":2010,"claim":"Mapped Ecm29 as a bipartite adaptor linking proteasomes to motors and endocytic machinery, explaining how proteasomes reach specific endosomes.","evidence":"Two-hybrid screens, mass spectrometry, domain mapping and confocal microscopy in human cells","pmids":["20682791"],"confidence":"High","gaps":["Cargo/proteolytic consequence at flotillin endosomes unknown","Direct vs indirect motor binding not distinguished structurally"]},{"year":2011,"claim":"Showed Ecm29's own stability and proteasome engagement are regulated by the Not4 E3 ligase, situating it within a regulatory circuit.","evidence":"Yeast deletion strains, co-immunoprecipitation, and ubiquitination assays","pmids":["21321079"],"confidence":"Medium","gaps":["Direct Not4 ubiquitination of Ecm29 not demonstrated","Mechanism by which Not4 promotes Ecm29-proteasome binding unclear"]},{"year":2011,"claim":"Established Ecm29 as a negative regulator that selectively recognizes and inhibits defective proteasomes, defining a surveillance function.","evidence":"Genetic epistasis (rpt5-Δ3, nas2Δ, hsm3Δ) with peptidase activity assays in yeast","pmids":["21878651"],"confidence":"Medium","gaps":["Biochemical mode of inhibition not yet defined here","Whether inhibition is reversible unknown"]},{"year":2013,"claim":"Provided the biochemical mechanism of inhibition—ATPase suppression and 20S gate closure—and localized binding to Rpt5, converting the genetic phenotype into a molecular model.","evidence":"In vitro peptidase/ATPase assays, in vivo substrate degradation, cross-linking MS, and EM gate analysis","pmids":["23995839"],"confidence":"High","gaps":["Atomic structure of Ecm29-proteasome complex absent","How aberrant-proteasome features are sensed not fully resolved"]},{"year":2013,"claim":"Connected Ecm29-proteasomes to innate immune signaling and autophagy, broadening its role beyond proteasome integrity.","evidence":"siRNA depletion in HEK-293/HeLa with immunoblot and immunofluorescence readouts of TLR3 pathway","pmids":["24084648"],"confidence":"Medium","gaps":["Direct proteasomal substrate in TLR3 pathway not identified","Whether effect is via proteasome tethering or activity control unclear"]},{"year":2016,"claim":"Revealed phosphorylation-dependent dual-site binding (α7-tail plus Rpt5), explaining how Ecm29 achieves specificity for holoenzymes and aberrant proteasomes.","evidence":"Yeast α7 phospho-tail mutants with co-IP and proteasome purification","pmids":["27302526"],"confidence":"Medium","gaps":["Kinase responsible for α7 phosphorylation not identified","Stoichiometry of the two-site engagement unresolved"]},{"year":2016,"claim":"Demonstrated in mice that Ecm29 is required for stress-induced 26S dissociation, linking it to oxidative-stress proteostasis in vivo.","evidence":"KIAA0368-deficient mice with native gel analysis and oxidative stress challenge","pmids":["26802743"],"confidence":"Medium","gaps":["Signal transducing oxidative state to Ecm29 unknown","Physiological consequence of failed dissociation only partly characterized"]},{"year":2017,"claim":"Identified Ecm29 as the main driver of stress-triggered 26S disassembly and proposed a structural mechanism (intrusion at the 20S-19S interface), conserved across species.","evidence":"Cross-linking-assisted affinity purification with SILAC MS and integrative structural modeling in human cells","pmids":["28821611"],"confidence":"High","gaps":["High-resolution structure of the disassembly intermediate lacking","Reversibility and reassembly kinetics not measured"]},{"year":2020,"claim":"Showed Ecm29 tethers proteasomes to the axon initial segment via ankyrin G, controlling NKCC1 levels and neuronal GABAergic maturation—a spatially defined physiological role.","evidence":"Ecm29 KO mice, domain-deletion constructs, imaging, electrophysiology, and rescue experiments","pmids":["31910261"],"confidence":"High","gaps":["Whether AIS proteasomes degrade NKCC1 directly not proven","Generality across neuron types untested"]},{"year":2021,"claim":"Established that Ecm29-controlled asymmetric proteasome distribution between centrosome and cortex coordinates actin dynamics and antigen presentation at the B-cell immune synapse.","evidence":"siRNA silencing in B cells with confocal imaging, actin flow, and antigen extraction/presentation assays","pmids":["34055780"],"confidence":"Medium","gaps":["Molecular link between proteasome position and F-actin regulation unclear","Knockdown rather than knockout; off-target not excluded"]},{"year":2023,"claim":"Extended ECPAS-driven 26S disassembly to glucose starvation and showed it sustains 20S-mediated degradation and survival, with relevance to nutrient-deprived tumors.","evidence":"ECPAS KO cells, subcomplex affinity purification, quantitative MS, in silico modeling, and xenograft model","pmids":["37384533"],"confidence":"High","gaps":["Sensor coupling glucose status to ECPAS conformation unknown","In vivo tumor dependence on ECPAS not directly tested by KO"]},{"year":2023,"claim":"Defined a cooperative ECPAS–PA200 axis in spermatogenesis with LPIN1 as a shared target, linking ECPAS to germ-cell proteostasis and structure.","evidence":"PA200/ECPAS double-knockout mice, MS substrate identification, immunostaining, and ultrastructural analysis","pmids":["37189334"],"confidence":"Medium","gaps":["Whether LPIN1 is a direct degradation substrate not shown","Single-KO contributions versus dKO not separated"]},{"year":2025,"claim":"Showed Ecm29-controlled proteasome activity in neuroglia governs CNS immune tolerance through fidelity of self-antigen generation.","evidence":"Inducible conditional Ecm29 KO mice, EAE model, immunopeptidome MS, AAV antigen rescue, and flow cytometry","pmids":["39786996"],"confidence":"Medium","gaps":["Molecular basis of altered antigen processing not mechanistically resolved","Whether effect reflects 26S dissociation or tethering function unclear"]},{"year":null,"claim":"A high-resolution structure of ECPAS bound to the proteasome and the upstream signals (kinases, sensors) that switch ECPAS between chaperone, inhibitor, disassembly, and tethering modes remain undefined.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No atomic-resolution ECPAS-proteasome structure","Signal-to-conformation coupling for stress-induced disassembly unknown","Direct degradation substrates across tissues largely uncatalogued"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[5,1]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[4,5,9,12]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[2,10,11]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[2]}],"localization":[{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[0,11]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[0,2]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[0]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[10,11]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[1,5,9,12]},{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[8,9,12]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[6,11,14]}],"complexes":["26S proteasome"],"partners":["RPT5","PSMA7/Α7","ANKYRIN G","VPS11","RAB11-FIP4","RABAPTIN","NOT4","PA200"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q5VYK3","full_name":"Proteasome adapter and scaffold protein ECM29","aliases":["Ecm29 proteasome adapter and scaffold","Proteasome-associated protein ECM29 homolog"],"length_aa":1845,"mass_kda":204.3,"function":"Adapter/scaffolding protein that binds to the 26S proteasome, motor proteins and other compartment specific proteins. May couple the proteasome to different compartments including endosome, endoplasmic reticulum and centrosome. May play a role in ERAD and other enhanced proteolysis (PubMed:15496406). Promotes proteasome dissociation under oxidative stress (By similarity)","subcellular_location":"Endoplasmic reticulum; Endoplasmic reticulum-Golgi intermediate compartment; Endosome; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome; Nucleus; Endosome, multivesicular body; Cytoplasmic vesicle","url":"https://www.uniprot.org/uniprotkb/Q5VYK3/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ECPAS","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000136813","cell_line_id":"CID001008","localizations":[{"compartment":"cytoplasmic","grade":3},{"compartment":"nucleoplasm","grade":1}],"interactors":[{"gene":"KIAA0368;ECM29","stoichiometry":10.0},{"gene":"PSMD11","stoichiometry":0.2},{"gene":"PSMD3","stoichiometry":0.2},{"gene":"PSMB3","stoichiometry":0.2},{"gene":"RANGAP1","stoichiometry":0.2},{"gene":"RAN","stoichiometry":0.2},{"gene":"PSMC6","stoichiometry":0.2},{"gene":"PSMD1","stoichiometry":0.2},{"gene":"PSMB5","stoichiometry":0.2},{"gene":"PSMC3","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID001008","total_profiled":1310},"omim":[{"mim_id":"616694","title":"ECM29 PROTEASOME ADAPTOR AND SCAFFOLD PROTEIN; ECPAS","url":"https://www.omim.org/entry/616694"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"skeletal muscle","ntpm":227.2}],"url":"https://www.proteinatlas.org/search/ECPAS"},"hgnc":{"alias_symbol":["FLJ22036","ECM29"],"prev_symbol":["KIAA0368"]},"alphafold":{"accession":"Q5VYK3","domains":[{"cath_id":"-","chopping":"113-187_217-292","consensus_level":"medium","plddt":85.2957,"start":113,"end":292},{"cath_id":"-","chopping":"555-636_652-683","consensus_level":"medium","plddt":89.3512,"start":555,"end":683},{"cath_id":"1.25.10.10","chopping":"1294-1536","consensus_level":"medium","plddt":86.3205,"start":1294,"end":1536},{"cath_id":"1.25.10.10","chopping":"1687-1845","consensus_level":"medium","plddt":86.6213,"start":1687,"end":1845},{"cath_id":"1.20.1050","chopping":"2-103","consensus_level":"high","plddt":84.1055,"start":2,"end":103}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q5VYK3","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q5VYK3-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q5VYK3-F1-predicted_aligned_error_v6.png","plddt_mean":83.75},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ECPAS","jax_strain_url":"https://www.jax.org/strain/search?query=ECPAS"},"sequence":{"accession":"Q5VYK3","fasta_url":"https://rest.uniprot.org/uniprotkb/Q5VYK3.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q5VYK3/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q5VYK3"}},"corpus_meta":[{"pmid":"28821611","id":"PMC_28821611","title":"The proteasome-interacting Ecm29 protein disassembles the 26S proteasome in response to oxidative stress.","date":"2017","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/28821611","citation_count":83,"is_preprint":false},{"pmid":"15496406","id":"PMC_15496406","title":"Characterization of mammalian Ecm29, a 26 S proteasome-associated protein that localizes to the nucleus and membrane vesicles.","date":"2004","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15496406","citation_count":70,"is_preprint":false},{"pmid":"21321079","id":"PMC_21321079","title":"Not4 E3 ligase contributes to proteasome assembly and functional integrity in part through Ecm29.","date":"2011","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/21321079","citation_count":68,"is_preprint":false},{"pmid":"20682791","id":"PMC_20682791","title":"A protein interaction network for Ecm29 links the 26 S proteasome to molecular motors and endosomal components.","date":"2010","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/20682791","citation_count":66,"is_preprint":false},{"pmid":"20620957","id":"PMC_20620957","title":"Ecm29 fulfils quality control functions in proteasome assembly.","date":"2010","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/20620957","citation_count":62,"is_preprint":false},{"pmid":"21878651","id":"PMC_21878651","title":"Loss of Rpt5 protein interactions with the core particle and Nas2 protein causes the formation of faulty proteasomes that are inhibited by Ecm29 protein.","date":"2011","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/21878651","citation_count":53,"is_preprint":false},{"pmid":"23995839","id":"PMC_23995839","title":"The proteasome-associated protein Ecm29 inhibits proteasomal ATPase activity and in vivo protein degradation by the proteasome.","date":"2013","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/23995839","citation_count":43,"is_preprint":false},{"pmid":"27302526","id":"PMC_27302526","title":"Phosphorylation of the C-terminal tail of proteasome subunit α7 is required for binding of the proteasome quality control factor Ecm29.","date":"2016","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/27302526","citation_count":23,"is_preprint":false},{"pmid":"26802743","id":"PMC_26802743","title":"KIAA0368-deficiency affects disassembly of 26S proteasome under oxidative stress condition.","date":"2016","source":"Journal of biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/26802743","citation_count":21,"is_preprint":false},{"pmid":"31910261","id":"PMC_31910261","title":"Ecm29-mediated proteasomal distribution modulates excitatory GABA responses in the developing brain.","date":"2020","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/31910261","citation_count":14,"is_preprint":false},{"pmid":"37384533","id":"PMC_37384533","title":"ECPAS/Ecm29-mediated 26S proteasome disassembly is an adaptive response to glucose starvation.","date":"2023","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/37384533","citation_count":13,"is_preprint":false},{"pmid":"24084648","id":"PMC_24084648","title":"Depletion of the 26S proteasome adaptor Ecm29 increases Toll-like receptor 3 signaling.","date":"2013","source":"Science signaling","url":"https://pubmed.ncbi.nlm.nih.gov/24084648","citation_count":12,"is_preprint":false},{"pmid":"37189334","id":"PMC_37189334","title":"Proteasome-Associated Proteins, PA200 and ECPAS, Are Essential for Murine Spermatogenesis.","date":"2023","source":"Biomolecules","url":"https://pubmed.ncbi.nlm.nih.gov/37189334","citation_count":11,"is_preprint":false},{"pmid":"34055780","id":"PMC_34055780","title":"Ecm29-Dependent Proteasome Localization Regulates Cytoskeleton Remodeling at the Immune Synapse.","date":"2021","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/34055780","citation_count":11,"is_preprint":false},{"pmid":"39786996","id":"PMC_39786996","title":"ECM29/proteasome-mediated self-antigen generation by CNS-resident neuroglia promotes regulatory T cell activation.","date":"2025","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/39786996","citation_count":1,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.05.27.656411","title":"Microbial Modulation of Host Plant Proteasome Activity Improves Heat Stress Tolerance","date":"2025-05-30","source":"bioRxiv","url":"https://doi.org/10.1101/2025.05.27.656411","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9146,"output_tokens":4400,"usd":0.046719,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12447,"output_tokens":4690,"usd":0.089743,"stage2_stop_reason":"end_turn"},"total_usd":0.136462,"stage1_batch_id":"msgbatch_01AsR7g8dGTEiEw9U83bJeWn","stage2_batch_id":"msgbatch_01YV5ZyxtFNUZEjxRcpd9jzb","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2004,\n      \"finding\": \"Mammalian Ecm29 is present exclusively on 26S proteasomes in HeLa cells and localizes to the centrosome and a subset of secretory compartments including endosomes, the ER, and the ERGIC, as determined by confocal immunofluorescence microscopy and glycerol-gradient fractionation. Ecm29 is up-regulated 2–3-fold in toxin-resistant CHO cells with increased ER-associated degradation, suggesting it couples 26S proteasomes to secretory compartments engaged in quality control.\",\n      \"method\": \"Antibody generation, glycerol-gradient fractionation, confocal immunofluorescence microscopy, CHO mutant cell line analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization by confocal microscopy with functional correlation in mutant CHO cells, single lab, two orthogonal methods\",\n      \"pmids\": [\"15496406\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Ecm29 controls the integrity of RP-CP (regulatory particle–core particle) assemblies in yeast, recognizing RP-CP species in which CP maturation is stalled due to the lack of distinct beta subunits. Reconstitution assays demonstrated that Ecm29 functions as a scaffold protein during remodeling of incompletely matured RP-CP assemblies into regular enzymes, and is degraded upon completion of CP maturation.\",\n      \"method\": \"Yeast genetics, proteasome reconstitution assays, biochemical fractionation\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution assays with genetic validation, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"20620957\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"The C-terminal half of human Ecm29 binds myosins and kinesins (molecular motors), while the N-terminal region binds endocytic proteins Vps11, Rab11-FIP4, and rabaptin. A central fragment of Ecm29 is sufficient for 26S proteasome binding. Ecm29-26S proteasomes are present on flotillin-positive endosomes but absent from caveolin- and clathrin-decorated endosomes. Expression of the central fragment reduces proteasome association with flotillin-positive endosomes.\",\n      \"method\": \"Genome-wide two-hybrid screens, mass spectrometry, confocal microscopy, glycerol-gradient fractionation, domain mapping with truncation constructs\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal two-hybrid and MS identification of interactors, domain-mapped binding, and confocal functional assay in single lab with multiple orthogonal methods\",\n      \"pmids\": [\"20682791\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Not4 E3 ligase associates with the regulatory particle (RP) of the proteasome holoenzyme and interacts with Ecm29. In the absence of Not4, Ecm29 interacts less well with the proteasome, becomes ubiquitinated and degraded. This indicates that appropriate Ecm29-proteasome interaction requires Not4, establishing Ecm29 as a proteasome chaperone whose stability depends on Not4-mediated regulation.\",\n      \"method\": \"Yeast genetics (deletion strains), co-immunoprecipitation, ubiquitination assay, proteasome purification and activity assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP and genetic epistasis in yeast, single lab, multiple methods\",\n      \"pmids\": [\"21321079\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Ecm29 is enriched on proteasomes purified from Saccharomyces cerevisiae rpt5-Δ3 strains (faulty proteasomes), and these Ecm29-containing proteasomes have reduced suc-LLVY-AMC hydrolytic activity. Deletion of ECM29 rescues phenotypes of rpt5-Δ3 and nas2Δ in an hsm3Δ background, establishing Ecm29 as a negative regulator/inhibitor that recognizes and inhibits aberrant proteasomes.\",\n      \"method\": \"Yeast genetics (deletion strains, epistasis analysis), proteasome purification, peptidase activity assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis combined with biochemical activity assay, single lab\",\n      \"pmids\": [\"21878651\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Ecm29 inhibits proteasomal ATPase activity and induces a closed conformation of the substrate entry channel of the 20S core particle. Besides inhibiting peptide substrate cleavage in vitro, Ecm29 inhibits degradation of ubiquitin-dependent and -independent substrates in vivo. Chemical cross-linking identified that Ecm29 binds to or in close proximity to proteasomal ATPase subunit Rpt5. Ecm29 preferentially associates with mutant and nucleotide-depleted proteasomes.\",\n      \"method\": \"In vitro peptidase and ATPase activity assays, in vivo ubiquitin-dependent substrate degradation assays, chemical cross-linking mass spectrometry, electron microscopy (gate conformation)\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro enzymatic assays with cross-linking MS mapping of interaction site and in vivo substrate degradation, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"23995839\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Depletion of Ecm29 increases abundance of TLR3 and increases levels of LC3β and p62 (autophagy mediators). Loss of Ecm29 enhances TLR3 signaling, characterized by increased TRAF3 levels, increased phosphorylation of effector kinases, increased nuclear localization of IRF3, and accumulation of signaling molecules at juxtanuclear recycling endosomes. This establishes that Ecm29-associated proteasomes play a role in mediating autophagy and attenuation of TLR3-dependent signaling.\",\n      \"method\": \"siRNA depletion of Ecm29 in HEK-293 and HeLa cells, immunoblotting, immunofluorescence microscopy\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — knockdown with multiple pathway readouts, single lab\",\n      \"pmids\": [\"24084648\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Yeast Ecm29 requires the phosphorylated C-terminal tail of the proteasome α7 subunit for its association with the proteasome. This represents the first example of phosphorylation-dependent binding of a proteasome regulatory factor. The ability of Ecm29 to bind mutant proteasomes requires both the α7-tail phosphorylation-dependent binding site and a previously identified Rpt5 binding site; the need for two binding sites on different subcomplexes explains the specificity of Ecm29 for proteasome holoenzymes.\",\n      \"method\": \"Yeast genetics (α7 tail phosphorylation mutants), co-immunoprecipitation/pulldown, proteasome purification\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic and biochemical demonstration of phospho-dependent binding, single lab, two complementary mutant approaches\",\n      \"pmids\": [\"27302526\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"KIAA0368-deficient (Ecm29 knockout) mice show normal peptidase activity and proteasome formation under basal conditions, but fail to dissociate 26S proteasomes under oxidative stress conditions where wild-type cells dissociate 26S proteasomes. This correlates with reduced degradation of damaged proteins and increased resistance to oxidative stress in KIAA0368-deficient cells, establishing Ecm29 as required for 26S proteasome dissociation under stress.\",\n      \"method\": \"KIAA0368-deficient mouse generation, native gel proteasome analysis, peptidase activity assays, oxidative stress challenge\",\n      \"journal\": \"Journal of biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockout mouse model with biochemical proteasome analysis, single lab\",\n      \"pmids\": [\"26802743\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Human Ecm29 is the main proteasome-interacting protein responsible for stress-triggered (H2O2) disassembly of the 26S proteasome. Cross-linking mass spectrometry mapped Ecm29 interactions within itself and with proteasome subunits; integrative structural modeling proposed that Ecm29 intrudes on the interaction between the 20S core particle and the 19S regulatory particle, disrupting proteasome structure in response to oxidative stress. Stress-induced 26S disassembly is conserved from yeast to human.\",\n      \"method\": \"XAP (in vivo cross-linking-assisted affinity purification) with SILAC quantitative MS, disuccinimidyl sulfoxide cross-linking MS, integrative structural modeling\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cross-linking MS with quantitative proteomics, structural modeling, conservation across species, multiple orthogonal methods\",\n      \"pmids\": [\"28821611\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Ecm29 mediates proteasome distribution to the axon initial segment (AIS) through interaction with the AIS scaffold protein ankyrin G; both the Ecm29 N-terminal domain and an intact AIS structure are required for transport and tethering of proteasomes in the AIS region. Ecm29 knockout in neurons increases NKCC1 protein density in the AIS, delays the GABAergic response switch, and increases action potential firing frequency at early postnatal ages. Ecm29 KO neurons show accelerated AIS developmental positioning, rescued by ectopic Ecm29 expression or NKCC1 inhibition.\",\n      \"method\": \"Ecm29 knockout mouse, confocal and live imaging, domain deletion constructs, electrophysiology, chemical convulsive seizure assay, rescue experiments\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with multiple cellular and physiological readouts, domain-mapped mechanism, rescue experiments, multiple orthogonal methods\",\n      \"pmids\": [\"31910261\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Ecm29 regulates proteasome distribution between the centrosome and cell cortex in B cells. Silencing Ecm29 shifts the proteasome from the centrosome to the cell cortex and immunological synapse (IS), resulting in increased F-actin at the centrosome, impaired centrosome and lysosome repositioning to the IS, defective antigen extraction and presentation, decreased actin retrograde flow in lamellipodia, and enhanced spreading. This establishes that Ecm29-controlled asymmetric proteasome distribution coordinates actin dynamics at the centrosome and IS.\",\n      \"method\": \"siRNA silencing of Ecm29 in B cells, confocal microscopy, actin dynamics measurement, antigen extraction and presentation assays\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — knockdown with multiple cellular readouts (localization, actin, antigen presentation), single lab\",\n      \"pmids\": [\"34055780\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ECPAS mediates 26S proteasome disassembly into 20S and 19S subcomplexes in response to glucose starvation. Loss of ECPAS abrogates 26S dissociation and reduces degradation of 20S proteasome substrates including puromycylated polypeptides. In silico modeling suggests ECPAS conformational changes initiate the disassembly process. ECPAS is also essential for ER stress response and cell survival during glucose starvation. Elevated 20S proteasome levels are found in glucose-deprived tumors in vivo in a xenograft model.\",\n      \"method\": \"ECPAS KO cells, subcomplex affinity purification, quantitative mass spectrometry, in silico structural modeling, xenograft mouse model, puromycylated polypeptide degradation assay\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO with quantitative proteomics, structural modeling, in vivo xenograft, multiple orthogonal methods, independent replication supported by prior oxidative stress work\",\n      \"pmids\": [\"37384533\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"PA200 and ECPAS work cooperatively during spermatogenesis; double knockout (dKO) mice are infertile with considerably reduced proteasome activity in testes and epididymides. In epididymal sperm, ECPAS localizes to the acrosome. Mass spectrometric analysis identified LPIN1 as a target protein for both PA200 and ECPAS (confirmed by immunoblotting and immunostaining). dKO sperm display disorganization of the mitochondrial sheath.\",\n      \"method\": \"Double-knockout mouse generation, mass spectrometry, immunoblotting, immunostaining, ultrastructural analysis, proteasome activity assay\",\n      \"journal\": \"Biomolecules\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with MS substrate identification and multiple validation methods, single lab\",\n      \"pmids\": [\"37189334\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Loss of Ecm29 in oligodendroglia or microglia (inducible conditional KO) increases susceptibility to experimental autoimmune encephalomyelitis (EAE) and reduces regulatory T cell populations in the spinal cord. Immunopeptidome profiling identified self-antigens (including NDUFA1p) whose generation fidelity depends on Ecm29/proteasome function, and intraspinal AAV-mediated expression of NDUFA1p ameliorates EAE and expands NDUFA1p-recognizing CD103+CD8+CD122+ Treg cells, establishing that Ecm29-controlled proteasome activity governs CNS immune tolerance through neuroglial antigen generation.\",\n      \"method\": \"Inducible conditional Ecm29 KO mice, EAE model, immunopeptidome profiling (MS), AAV-mediated antigen expression, flow cytometry\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — conditional genetic KO with immunopeptidome MS and in vivo rescue, single lab, multiple methods\",\n      \"pmids\": [\"39786996\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ECPAS/Ecm29 is a large HEAT-repeat scaffold protein that associates with 26S proteasomes as an adaptor and quality-control factor: it recognizes aberrant or incompletely assembled proteasomes (via dual binding sites on α7-phospho tail and Rpt5 of the 19S), inhibits proteasomal ATPase activity and substrate entry by inducing gate closure, and drives 26S-to-20S/19S disassembly in response to stress signals (oxidative stress, glucose starvation) by intruding between the 20S and 19S subcomplexes; additionally, Ecm29 acts as a subcellular adaptor that tethers proteasomes to flotillin-positive endosomes (via motor protein and endocytic protein interactions), to the axon initial segment (via ankyrin G), and to the centrosome of immune cells, thereby spatially coordinating proteolysis with processes including secretory-pathway quality control, neuronal maturation (GABA switch), cytoskeletal remodeling at the immune synapse, spermatogenesis, and CNS immune tolerance through neuroglial antigen generation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ECPAS (Ecm29) is a large HEAT-repeat scaffold protein that associates with the 26S proteasome as a quality-control and adaptor factor, coupling proteolysis to proteasome integrity surveillance, stress responses, and subcellular targeting [#0, #2]. It functions as a proteasome chaperone that monitors regulatory particle\\u2013core particle (RP-CP) assembly, recognizing stalled or aberrant assemblies and remodeling them into mature enzymes [#1]. ECPAS preferentially associates with mutant and nucleotide-depleted proteasomes through dual binding sites\\u2014the phosphorylated C-terminal tail of the \\u03b17 core subunit and the Rpt5 ATPase of the 19S regulatory particle\\u2014a requirement for two sites on different subcomplexes that explains its specificity for holoenzymes and aberrant species [#4, #5, #7]. Engagement of aberrant proteasomes inhibits ATPase activity and induces closure of the 20S substrate-entry gate, blocking degradation of ubiquitin-dependent and -independent substrates [#5]. Under stress\\u2014oxidative stress or glucose starvation\\u2014ECPAS is the principal driver of 26S disassembly into 20S and 19S subcomplexes, intruding on the 20S\\u201319S interface, a function conserved from yeast to human [#8, #9, #12]. Beyond holoenzyme regulation, ECPAS acts as a subcellular adaptor: its C-terminal half binds molecular motors (myosins, kinesins) and its N-terminal region binds endocytic proteins, tethering proteasomes to flotillin-positive endosomes [#2], to the axon initial segment via ankyrin G where it controls NKCC1 levels and the GABAergic developmental switch [#10], and to the centrosome of B cells to coordinate proteasome distribution with actin dynamics at the immune synapse [#11]. ECPAS additionally cooperates with PA200 during spermatogenesis, targeting LPIN1 and supporting mitochondrial sheath organization [#13], and governs CNS immune tolerance through fidelity of neuroglial self-antigen generation [#14].\",\n  \"teleology\": [\n    {\n      \"year\": 2004,\n      \"claim\": \"Established that mammalian Ecm29 is a dedicated 26S proteasome partner with a non-uniform subcellular distribution, raising the possibility that it couples proteolysis to specific compartments.\",\n      \"evidence\": \"Glycerol-gradient fractionation and confocal immunofluorescence in HeLa and toxin-resistant CHO cells\",\n      \"pmids\": [\"15496406\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional role at the centrosome/secretory compartments not defined\", \"No molecular mechanism for targeting\", \"Correlative link to ERAD only\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Defined Ecm29 as a scaffold/chaperone for proteasome biogenesis, answering whether it acts on assembled enzymes versus assembly intermediates.\",\n      \"evidence\": \"Yeast genetics and proteasome reconstitution assays of stalled RP-CP species\",\n      \"pmids\": [\"20620957\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of intermediate recognition not resolved\", \"Trigger for Ecm29 degradation upon maturation not detailed\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Mapped Ecm29 as a bipartite adaptor linking proteasomes to motors and endocytic machinery, explaining how proteasomes reach specific endosomes.\",\n      \"evidence\": \"Two-hybrid screens, mass spectrometry, domain mapping and confocal microscopy in human cells\",\n      \"pmids\": [\"20682791\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cargo/proteolytic consequence at flotillin endosomes unknown\", \"Direct vs indirect motor binding not distinguished structurally\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Showed Ecm29's own stability and proteasome engagement are regulated by the Not4 E3 ligase, situating it within a regulatory circuit.\",\n      \"evidence\": \"Yeast deletion strains, co-immunoprecipitation, and ubiquitination assays\",\n      \"pmids\": [\"21321079\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct Not4 ubiquitination of Ecm29 not demonstrated\", \"Mechanism by which Not4 promotes Ecm29-proteasome binding unclear\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Established Ecm29 as a negative regulator that selectively recognizes and inhibits defective proteasomes, defining a surveillance function.\",\n      \"evidence\": \"Genetic epistasis (rpt5-\\u03943, nas2\\u0394, hsm3\\u0394) with peptidase activity assays in yeast\",\n      \"pmids\": [\"21878651\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Biochemical mode of inhibition not yet defined here\", \"Whether inhibition is reversible unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Provided the biochemical mechanism of inhibition\\u2014ATPase suppression and 20S gate closure\\u2014and localized binding to Rpt5, converting the genetic phenotype into a molecular model.\",\n      \"evidence\": \"In vitro peptidase/ATPase assays, in vivo substrate degradation, cross-linking MS, and EM gate analysis\",\n      \"pmids\": [\"23995839\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic structure of Ecm29-proteasome complex absent\", \"How aberrant-proteasome features are sensed not fully resolved\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Connected Ecm29-proteasomes to innate immune signaling and autophagy, broadening its role beyond proteasome integrity.\",\n      \"evidence\": \"siRNA depletion in HEK-293/HeLa with immunoblot and immunofluorescence readouts of TLR3 pathway\",\n      \"pmids\": [\"24084648\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct proteasomal substrate in TLR3 pathway not identified\", \"Whether effect is via proteasome tethering or activity control unclear\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Revealed phosphorylation-dependent dual-site binding (\\u03b17-tail plus Rpt5), explaining how Ecm29 achieves specificity for holoenzymes and aberrant proteasomes.\",\n      \"evidence\": \"Yeast \\u03b17 phospho-tail mutants with co-IP and proteasome purification\",\n      \"pmids\": [\"27302526\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Kinase responsible for \\u03b17 phosphorylation not identified\", \"Stoichiometry of the two-site engagement unresolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Demonstrated in mice that Ecm29 is required for stress-induced 26S dissociation, linking it to oxidative-stress proteostasis in vivo.\",\n      \"evidence\": \"KIAA0368-deficient mice with native gel analysis and oxidative stress challenge\",\n      \"pmids\": [\"26802743\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Signal transducing oxidative state to Ecm29 unknown\", \"Physiological consequence of failed dissociation only partly characterized\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Identified Ecm29 as the main driver of stress-triggered 26S disassembly and proposed a structural mechanism (intrusion at the 20S-19S interface), conserved across species.\",\n      \"evidence\": \"Cross-linking-assisted affinity purification with SILAC MS and integrative structural modeling in human cells\",\n      \"pmids\": [\"28821611\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"High-resolution structure of the disassembly intermediate lacking\", \"Reversibility and reassembly kinetics not measured\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Showed Ecm29 tethers proteasomes to the axon initial segment via ankyrin G, controlling NKCC1 levels and neuronal GABAergic maturation\\u2014a spatially defined physiological role.\",\n      \"evidence\": \"Ecm29 KO mice, domain-deletion constructs, imaging, electrophysiology, and rescue experiments\",\n      \"pmids\": [\"31910261\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether AIS proteasomes degrade NKCC1 directly not proven\", \"Generality across neuron types untested\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Established that Ecm29-controlled asymmetric proteasome distribution between centrosome and cortex coordinates actin dynamics and antigen presentation at the B-cell immune synapse.\",\n      \"evidence\": \"siRNA silencing in B cells with confocal imaging, actin flow, and antigen extraction/presentation assays\",\n      \"pmids\": [\"34055780\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular link between proteasome position and F-actin regulation unclear\", \"Knockdown rather than knockout; off-target not excluded\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Extended ECPAS-driven 26S disassembly to glucose starvation and showed it sustains 20S-mediated degradation and survival, with relevance to nutrient-deprived tumors.\",\n      \"evidence\": \"ECPAS KO cells, subcomplex affinity purification, quantitative MS, in silico modeling, and xenograft model\",\n      \"pmids\": [\"37384533\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Sensor coupling glucose status to ECPAS conformation unknown\", \"In vivo tumor dependence on ECPAS not directly tested by KO\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Defined a cooperative ECPAS\\u2013PA200 axis in spermatogenesis with LPIN1 as a shared target, linking ECPAS to germ-cell proteostasis and structure.\",\n      \"evidence\": \"PA200/ECPAS double-knockout mice, MS substrate identification, immunostaining, and ultrastructural analysis\",\n      \"pmids\": [\"37189334\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether LPIN1 is a direct degradation substrate not shown\", \"Single-KO contributions versus dKO not separated\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Showed Ecm29-controlled proteasome activity in neuroglia governs CNS immune tolerance through fidelity of self-antigen generation.\",\n      \"evidence\": \"Inducible conditional Ecm29 KO mice, EAE model, immunopeptidome MS, AAV antigen rescue, and flow cytometry\",\n      \"pmids\": [\"39786996\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis of altered antigen processing not mechanistically resolved\", \"Whether effect reflects 26S dissociation or tethering function unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A high-resolution structure of ECPAS bound to the proteasome and the upstream signals (kinases, sensors) that switch ECPAS between chaperone, inhibitor, disassembly, and tethering modes remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No atomic-resolution ECPAS-proteasome structure\", \"Signal-to-conformation coupling for stress-induced disassembly unknown\", \"Direct degradation substrates across tissues largely uncatalogued\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [5, 1]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [4, 5, 9, 12]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [2, 10, 11]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [0, 11]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [0, 2]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [10, 11]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [1, 5, 9, 12]},\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [8, 9, 12]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [6, 11, 14]}\n    ],\n    \"complexes\": [\"26S proteasome\"],\n    \"partners\": [\"Rpt5\", \"PSMA7/\\u03b17\", \"ankyrin G\", \"Vps11\", \"Rab11-FIP4\", \"rabaptin\", \"Not4\", \"PA200\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}