{"gene":"ERAP1","run_date":"2026-06-09T23:54:43","timeline":{"discoveries":[{"year":2005,"finding":"ERAP1 and ERAP2 form heterodimeric complexes in the endoplasmic reticulum and function concertedly to trim MHC class I peptide precursors; ERAP1 alone cannot remove certain N-terminal amino acids that ERAP2 trims efficiently, requiring the combined action of both enzymes for full trimming both in vitro and in vivo antigen presentation.","method":"Co-localization by immunofluorescence, physical association by co-immunoprecipitation, in vitro peptide digestion assays, cellular antigen presentation assays","journal":"Nature immunology","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — reciprocal Co-IP establishing heterodimer, in vitro enzymatic assay, and in vivo antigen presentation readout in a single study; findings on concerted trimming replicated in subsequent work","pmids":["15908954"],"is_preprint":false},{"year":2011,"finding":"X-ray crystal structures of human ERAP1 in open and closed conformations reveal it is a zinc-metallopeptidase with HEXXH-(X)18-E zinc-binding and GAMEN motifs characteristic of the gluzincin protease family; extensive domain movements including active-site closure are observed along the catalytic path, and the K528R disease-associated variant shows altered peptide processing characteristics possibly related to impaired interdomain interactions.","method":"X-ray crystallography (open and closed state structures); site-directed mutagenesis of K528R; in vitro peptide processing assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structures with functional mutagenesis validation; independently corroborated by multiple subsequent structural studies","pmids":["21508329"],"is_preprint":false},{"year":2011,"finding":"X-ray crystal structure of human ERAP1 bound to bestatin reveals an open conformation with a large interior compartment and an extended groove from the catalytic center that accommodates long peptides; structural and biochemical analyses demonstrate a length-dependent trimming mechanism whereby binding of long (but not short) substrates induces a conformational change reorienting a key catalytic residue toward the active site.","method":"X-ray crystallography (ERAP1–bestatin complex); biochemical trimming assays with peptides of varying length","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus biochemical mechanistic validation in a single rigorous study; the length-dependent conformational change mechanism was subsequently supported by additional structural and SAXS studies","pmids":["21478864"],"is_preprint":false},{"year":2002,"finding":"ERAP1 (ARTS-1) is a type II integral membrane aminopeptidase that physically binds the extracellular domain of TNFR1 and promotes TNFR1 ectodomain shedding; overexpression increases TNFR1 shedding while antisense knockdown decreases it; ARTS-1 does not bind TNFR2 and does not possess sheddase activity itself.","method":"Yeast two-hybrid screen; co-immunoprecipitation in human pulmonary epithelial and endothelial cells; overexpression and antisense knockdown with TNFR1 shedding quantification; in vitro aminopeptidase activity assay","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP in two cell types, functional gain- and loss-of-function experiments, multiple orthogonal methods in one study","pmids":["12189246"],"is_preprint":false},{"year":2003,"finding":"ERAP1 (ARTS-1) directly binds IL-6Rα and is required for constitutive IL-6Rα shedding; ARTS-1 catalytic activity is necessary for constitutive shedding; knockout cells lack basal IL-6Rα shedding, and overexpression increases it.","method":"Reciprocal co-immunoprecipitation; ARTS-1 overexpression and knockout cell lines; shedding quantification; catalytic activity requirement demonstrated by enzymatic inhibition","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, KO cells with defined shedding phenotype, catalytic dependency demonstrated; multiple orthogonal methods","pmids":["12748171"],"is_preprint":false},{"year":2006,"finding":"In mice, ERAP1 is the major enzyme trimming precursor peptides in the endoplasmic reticulum; loss of ERAP1 markedly shifts the hierarchy of immunodominance in viral infections, generating some antigenic peptides while destroying others by over-trimming to sub-optimal lengths, demonstrating that ERAP1 trimming and resultant peptide-MHC abundance are dominant factors establishing immunodominance.","method":"ERAP1 knockout mice; viral infection model (influenza); CD8+ T cell response hierarchy measured by peptide-MHC tetramer staining and cytotoxicity assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — clean KO with specific immunodominance phenotype, replicated across multiple viral epitopes in a single rigorous study","pmids":["16754858"],"is_preprint":false},{"year":2008,"finding":"ERAP1 trimming efficiency is strongly influenced by internal (non-N-terminal) residues of the peptide substrate; positively charged or hydrophobic residues at internal positions increase trimming rates by up to 100-fold for single substitutions and >40,000-fold for multiple substitutions, indicating ERAP1 recognizes the full length of its substrate via a large negatively charged internal cavity adjacent to the active site.","method":"Systematic in vitro peptide trimming assays with collections of peptide substrates; molecular modeling of ERAP1 cavity","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — rigorous in vitro enzymatic assay with systematic substrate variation; molecular modeling supports but does not independently validate the structural explanation; single lab","pmids":["18987748"],"is_preprint":false},{"year":2006,"finding":"The Lys528Arg polymorphism of ERAP1 (A-LAP) significantly reduces enzymatic aminopeptidase activity; site-directed mutagenesis of Lys528 to multiple amino acids (Ala, Met, His, Arg) all caused decreased activity, and molecular modeling suggests Lys528 is near the substrate pocket entrance and maintains its optimal structure.","method":"Site-directed mutagenesis; in vitro aminopeptidase activity assays with fluorogenic substrates; molecular modeling","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro mutagenesis and enzymatic assay, single lab; molecular modeling is supportive but not crystallographic","pmids":["16513116"],"is_preprint":false},{"year":2000,"finding":"ERAP1 (PILS-AP) is a signal-sequence-bearing M1 family zinc-dependent aminopeptidase; when expressed as a GFP fusion protein it localizes to intracellular vesicles in COS-7 and BHK cells; it exhibits selective leucyl (and to a lesser extent methionyl) aminopeptidase activity that is inhibited by chelators of bivalent cations but, unusually, not by puromycin.","method":"GFP fusion protein live-cell imaging (subcellular localization); expression in Sf9 insect cells; in vitro enzymatic activity assay with aminoacyl β-naphthylamide substrates; inhibitor profiling","journal":"European journal of biochemistry","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — direct localization by live imaging tied to enzymatic characterization; single lab but multiple orthogonal methods","pmids":["10824104"],"is_preprint":false},{"year":2006,"finding":"ERAP1 (ARTS-1) forms a calcium-dependent complex with nucleobindin 2 (NUCB2) via NUCB2's helix-loop-helix domains binding the ARTS-1 extracellular domain; this NUCB2·ARTS-1 complex associates with a subset of cellular TNFR1 within intracytoplasmic vesicles, and both proteins are required for constitutive release of full-length TNFR1 in exosome-like vesicles and for inducible proteolytic cleavage of soluble TNFR1 ectodomains.","method":"Yeast two-hybrid screen; co-immunoprecipitation in HUVEC; confocal microscopy; RNA interference knockdown of NUCB2 and ARTS-1 with TNFR1 release quantification","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus RNAi loss-of-function with specific vesicle-release phenotype and confocal localization; single lab","pmids":["16407280"],"is_preprint":false},{"year":2008,"finding":"ERAP1 (ARTS-1) physically associates with RBMX (a heterogeneous nuclear ribonucleoprotein) as shown by co-immunoprecipitation; RNAi knockdown of RBMX reduces both constitutive TNFR1 exosome-like vesicle release and IL-1β-induced proteolytic cleavage of TNFR1 ectodomains, while RBMX overexpression has the opposite effect.","method":"Co-immunoprecipitation; RNA interference; overexpression with TNFR1 release quantification","journal":"Biochemical and biophysical research communications","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP and RNAi with functional readout; single lab, single method for binding","pmids":["18445477"],"is_preprint":false},{"year":2011,"finding":"HCMV miR-US4-1 specifically downregulates ERAP1 expression during viral infection, thereby inhibiting trimming of HCMV-derived peptide precursors and reducing susceptibility of infected cells to HCMV-specific cytotoxic T lymphocytes, constituting a viral miRNA-based CTL-evasion mechanism targeting the MHC class I antigen-processing pathway.","method":"Viral infection of cell lines; miRNA overexpression and knockdown; ERAP1 protein/mRNA quantification; peptide trimming assay; CTL killing assay","journal":"Nature immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (miRNA functional assay, trimming assay, CTL killing) in a single rigorous study; published in high-tier journal with thorough mechanistic follow-up","pmids":["21892175"],"is_preprint":false},{"year":2013,"finding":"p53 directly upregulates ERAP1 expression by binding to a cognate response element in the ERAP1 gene, thereby increasing MHC class I surface expression; silencing p53 decreases ERAP1 protein and MHC class I expression; during H1N1 influenza infection, virus-activated p53 leads to ERAP1 upregulation and increased MHC class I expression.","method":"Chromatin immunoprecipitation sequencing (ChIP-seq) identifying p53 binding at ERAP1 locus; gene expression analysis; p53 siRNA knockdown; viral infection model","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — ChIP-seq identifying direct promoter binding plus loss-of-function with defined MHC I phenotype; orthogonal validation in infection model","pmids":["23965983"],"is_preprint":false},{"year":2014,"finding":"Stabilized ERAP1-ERAP2 heterodimers produce mature MHC class I epitopes more efficiently than a mixture of the two enzymes unable to dimerize; physical interaction with ERAP2 allosterically changes basic enzymatic parameters of ERAP1 and improves its substrate-binding affinity, indicating that dimerization creates complexes with superior peptide-trimming efficacy.","method":"Production of stabilized ERAP1-ERAP2 heterodimers; in vitro peptide-trimming assays comparing heterodimer vs. non-dimerizing enzyme mixtures; enzymatic kinetics measurements (Km, kcat)","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro reconstitution with stabilized heterodimers, enzymatic kinetics, and head-to-head comparison; findings corroborated by independent study (PMID 27514473)","pmids":["24928998"],"is_preprint":false},{"year":2016,"finding":"ERAP1-ERAP2 heterodimers can trim MHC class I-bound precursor peptides to their correct final lengths (albeit more slowly than free precursors), and such trimming increases the conformational stability of MHC I/peptide complexes, supporting a model of ERAP1/2 as peptide editors acting on MHC I-bound substrates.","method":"In vitro trimming assay using ERAP1/2 heterodimers with free and HLA-B*0801-bound N-terminally extended peptides; thermal stability measurements of MHC I/peptide complexes","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro reconstitution assay with heterodimers and MHC-bound peptides; single lab, novel finding of MHC-bound trimming","pmids":["27514473"],"is_preprint":false},{"year":2015,"finding":"ERAP1 silencing or pharmacological inhibition in HLA-B27-expressing antigen-presenting cells downregulates surface HLA-B27 free heavy chain (FHC) expression, reduces IL-2 production by KIR3DL2-reporter cells, and suppresses Th17 expansion and IL-17A secretion by AS CD4+ T cells; AS-protective ERAP1 variants K528R and Q730E are associated with reduced FHC expression on patient monocytes.","method":"siRNA knockdown; pharmacological ERAP1 inhibition; flow cytometry (surface FHC and MHC I expression); KIR3DL2 reporter co-culture; Th17 intracellular cytokine staining; ELISA","journal":"Annals of the rheumatic diseases","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean knockdown and pharmacological inhibition with multiple downstream cellular readouts; single lab","pmids":["26130142"],"is_preprint":false},{"year":2016,"finding":"ERAP1 knockdown increases accumulation of HLA-B27 on the cell surface including disulfide-linked dimers but has no effect on HLA-B18 or HLA-B51, demonstrating that normal ERAP1 levels specifically reduce aberrant and disulfide-linked forms of HLA-B27 in monocytes.","method":"ERAP1 siRNA knockdown in HLA-B27-expressing U937 monocytic cells; immunoprecipitation; isoelectric focusing; immunoblotting (non-reducing gels); flow cytometry with HLA-B27-specific antibodies","journal":"Molecular immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple biochemical methods with clean KD and specific HLA-B27 phenotype; single lab","pmids":["27107845"],"is_preprint":false},{"year":2019,"finding":"ERAP1 binds the deubiquitylase USP47, displaces USP47-associated βTrCP (the substrate-receptor subunit of SCFβTrCP ubiquitin ligase), and promotes βTrCP degradation; this results in modulation of Gli transcription factors and enhancement of Hedgehog pathway activity; genetic or pharmacological inhibition of ERAP1 suppresses Hh-dependent tumor growth in vitro and in vivo.","method":"Co-immunoprecipitation (ERAP1-USP47-βTrCP); ubiquitination assays; Gli reporter assays; ERAP1 genetic knockdown and pharmacological inhibition; in vivo tumor growth assays (mouse models)","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP establishing ternary complex, functional reporter assay, in vivo tumor model; single lab but multiple orthogonal methods","pmids":["31341163"],"is_preprint":false},{"year":2015,"finding":"Genetic or pharmacological inhibition of ERAP1 on human tumor cell lines perturbs engagement of multiple classes of inhibitory NK cell receptors (KIR by classical pMHC-I; CD94-NKG2A by nonclassical pMHC-I), leading to NK cell killing; the protective effect of pMHC-I could be restored by addition of high-affinity peptides, indicating ERAP1 positively modifies the affinity of natural MHC ligands.","method":"siRNA knockdown and pharmacological inhibition of ERAP1; NK cell cytotoxicity assays; flow cytometry of MHC-I surface expression; peptide rescue experiments; killing of autologous/allogeneic lymphoblastoid cell lines","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KD and pharmacological inhibition with multiple NK receptor functional readouts and peptide rescue experiment; single lab","pmids":["25592150"],"is_preprint":false},{"year":2019,"finding":"ERAP1-mediated trimming of MHC I-bound precursor peptides requires peptides of at least 14 amino acids in length; N-terminal residue extensions protrude out of the HLA-B*0801 A pocket while the core peptide adopts the standard bound conformation; HLA-B*0801 residue 62 is critical for opening the A pocket to accommodate extended peptides.","method":"X-ray crystallography of HLA-B*0801 complexes with nested N-terminally extended peptides (1.40–1.65 Å); thermal stability assays; in vitro ERAP1 trimming assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — high-resolution crystal structures plus biochemical trimming assay defining minimal length requirement for MHC-bound trimming; multiple orthogonal methods","pmids":["31601650"],"is_preprint":false},{"year":2021,"finding":"Solution SAXS and X-ray crystallography demonstrate that ERAP1 undergoes domain closure in solution upon binding of long peptide substrates and allosteric activators; structural reconfigurations of the ERAP1 active site are physically linked to domain closure; chemical crosslinking localizes alternate C-terminal binding sites; the K528R polymorphism disease association is mechanistically explained by its role in domain closure dynamics.","method":"Small-angle X-ray scattering (SAXS) in solution; X-ray crystallography; chemical crosslinking with mass spectrometry; enzymatic assays with allosteric modulators","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 1 / Strong — SAXS plus crystallography plus crosslinking-MS, multiple orthogonal structural methods with enzymatic validation; single comprehensive study","pmids":["34489420"],"is_preprint":false},{"year":2017,"finding":"HCMV miR-UL112-5p targets the ERAP1 3′ UTR to inhibit ERAP1 expression and processing of the HCMV pp65495-503 peptide, thereby reducing CTL lysis of infected cells; a naturally occurring rs17481334 G variant in the ERAP1 3′ UTR prevents miR-UL112-5p binding and preserves ERAP1 expression, making GG homozygous fibroblasts more efficient at viral antigen trimming and more susceptible to CTL killing.","method":"miRNA target-site validation (3′ UTR reporter assay); ERAP1 RNA and protein quantification in genotyped fibroblasts; in vitro trimming assay; CTL cytotoxicity assay; HCMV seropositivity analysis","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — 3′ UTR reporter plus functional trimming and CTL assays in genotyped cells; single lab but multiple orthogonal methods","pmids":["28746870"],"is_preprint":false},{"year":2021,"finding":"In psoriasis, ERAP1 generates the causative HLA-C*06:02-restricted melanocyte autoantigen by trimming N-terminally elongated peptide precursors; an ERAP1 risk haplotype produces the autoantigen much more efficiently and increases HLA-C expression and stimulation of a psoriatic autoreactive TCR significantly more than a protective haplotype; HLA-C surface expression decreases more upon ERAP1 knockout than overall HLA class I.","method":"ERAP1 genetically modified cell lines; TCR activation assay with psoriatic autoreactive TCR; flow cytometry of HLA-C surface expression; ERAP1 knockout; in vitro peptide trimming with recombinant ERAP1 variants","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional TCR activation assay with KO cells and allotype-defined recombinant ERAP1 variants; single lab; multiple methods","pmids":["34580106"],"is_preprint":false},{"year":2022,"finding":"ERAP1 functions as an inflammation-induced hepatokine: hepatic ERAP1 overexpression attenuates systemic and skeletal muscle insulin sensitivity while knockdown has the opposite effect; mechanistically, secreted ERAP1 interacts with β2 adrenergic receptor (ADRB2) and reduces its expression by decreasing USP33-mediated deubiquitination, thereby disrupting ADRB2-stimulated insulin signaling in skeletal muscle.","method":"Hepatic ERAP1 overexpression and knockdown in mice (HFD model); serum ERAP1 measurement; co-immunoprecipitation of ERAP1 with ADRB2; ubiquitination assay; ADRB2 protein quantification; insulin signaling pathway analysis in skeletal muscle","journal":"Diabetes","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo gain/loss-of-function with Co-IP identifying ERAP1-ADRB2 interaction and ubiquitination mechanism; single lab, novel non-immune function","pmids":["35192681"],"is_preprint":false},{"year":2018,"finding":"ERAP1 deletion in ERAP1−/− mice leads to development of hallmark skeletal features of ankylosing spondylitis (spinal ankylosis, osteoporosis, spinal inflammation), spontaneous intestinal dysbiosis, and increased susceptibility to DSS-induced colitis; these mice have reduced Tr1-like regulatory T cells and tolerogenic dendritic cells while maintaining normal Foxp3+ Treg numbers.","method":"ERAP1 knockout mice; µCT imaging; histology; microbiota transfer (cross-fostering); flow cytometry of immune cell populations","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO with specific skeletal and immunological phenotypes using multiple readouts; single lab","pmids":["30127455"],"is_preprint":false}],"current_model":"ERAP1 is an ER-resident zinc-metallopeptidase (M1/gluzincin family) that trims N-terminally extended peptide precursors for loading onto MHC class I molecules via a length-dependent, allosterically regulated mechanism involving domain closure upon long-substrate binding; it forms catalytically superior heterodimers with ERAP2; it also promotes TNFR1 and IL-6Rα ectodomain shedding via direct receptor binding, regulates HLA-B27 free heavy chain levels and NK/T cell responses, is transcriptionally induced by p53, is targeted for immune evasion by HCMV miRNAs, interacts with USP47/βTrCP to modulate Hedgehog signaling, and functions as a hepatokine that impairs skeletal muscle insulin sensitivity through ADRB2-USP33 deubiquitination."},"narrative":{"mechanistic_narrative":"ERAP1 is an endoplasmic-reticulum-resident, zinc-dependent M1/gluzincin aminopeptidase that shapes the MHC class I peptide repertoire by trimming N-terminally extended precursor peptides to their mature lengths for antigen presentation [PMID:15908954, PMID:16754858]. Crystallographic and solution-scattering analyses define a multidomain enzyme bearing the HEXXH-(X)18-E zinc-binding and GAMEN motifs that cycles between open and closed conformations; binding of long peptide substrates or allosteric activators drives active-site closure and reorients a key catalytic residue, providing a structural basis for its length-dependent 'molecular ruler' trimming and for recognition of internal substrate residues via a large interior cavity [PMID:21508329, PMID:21478864, PMID:18987748, PMID:34489420]. ERAP1 partners with ERAP2 to form ER heterodimers whose dimerization allosterically enhances substrate affinity and trimming efficacy beyond either enzyme alone, and it can edit precursor peptides while bound to MHC class I, requiring a minimum substrate length to engage MHC-bound peptides [PMID:15908954, PMID:24928998, PMID:27514473, PMID:31601650]. Through this trimming activity ERAP1 establishes CD8+ T cell immunodominance hierarchies, sets surface levels and conformational stability of MHC class I (including disulfide-linked HLA-B27 free heavy chains), and tunes NK-cell inhibitory receptor engagement by modifying the affinity of natural MHC ligands [PMID:16754858, PMID:26130142, PMID:27107845, PMID:25592150]; an ERAP1 risk haplotype efficiently generates an HLA-C*06:02-restricted melanocyte autoantigen in psoriasis [PMID:34580106]. ERAP1 expression is directly induced by p53 and is suppressed by HCMV miRNAs (miR-US4-1 and miR-UL112-5p) as a CTL-evasion strategy [PMID:21892175, PMID:23965983, PMID:28746870]. Beyond antigen processing, ERAP1 (originally identified as ARTS-1) binds the ectodomains of TNFR1 and IL-6Rα to promote their shedding [PMID:12189246, PMID:12748171], modulates Hedgehog signaling by displacing βTrCP from USP47 [PMID:31341163], and acts as a hepatokine that impairs skeletal-muscle insulin sensitivity by binding ADRB2 and reducing its USP33-mediated deubiquitination [PMID:35192681]. ERAP1-deficient mice develop ankylosing-spondylitis-like skeletal disease and intestinal dysbiosis [PMID:30127455].","teleology":[{"year":2000,"claim":"Established ERAP1's basic biochemical identity, answering whether the protein is an enzyme and where it acts.","evidence":"GFP-fusion live-cell imaging and in vitro aminopeptidase assays with inhibitor profiling","pmids":["10824104"],"confidence":"Medium","gaps":["Vesicular localization in COS-7/BHK does not pinpoint the ER residence later established","Substrate specificity defined only with model aminoacyl substrates, not antigenic peptides"]},{"year":2002,"claim":"Revealed an antigen-processing-independent role by showing ERAP1 binds TNFR1 and promotes its ectodomain shedding, raising the question of how an aminopeptidase regulates receptor shedding.","evidence":"Yeast two-hybrid, reciprocal Co-IP in two cell types, gain/loss-of-function shedding assays","pmids":["12189246"],"confidence":"High","gaps":["ERAP1 itself lacks sheddase activity, so the molecular link to the actual protease is unresolved","Selectivity for TNFR1 over TNFR2 mechanism not explained"]},{"year":2003,"claim":"Extended the shedding role to IL-6Rα and showed catalytic activity is required, distinguishing this function from passive receptor binding.","evidence":"Reciprocal Co-IP, KO cells, enzymatic inhibition of shedding","pmids":["12748171"],"confidence":"High","gaps":["How aminopeptidase activity mechanistically enables shedding is undefined","Physiological substrates cleaved during shedding not identified"]},{"year":2005,"claim":"Defined ERAP1's central antigen-processing function by showing it forms ER heterodimers with ERAP2 to concertedly trim MHC I peptide precursors.","evidence":"Co-localization, Co-IP, in vitro digestion and cellular antigen presentation assays","pmids":["15908954"],"confidence":"High","gaps":["Structural basis of the heterodimer not resolved here","Quantitative contribution of each enzyme to the repertoire unclear"]},{"year":2006,"claim":"Demonstrated in vivo that ERAP1 trimming dominantly shapes CD8+ T cell immunodominance, establishing physiological consequence of trimming.","evidence":"ERAP1 knockout mice, influenza infection, tetramer staining and cytotoxicity","pmids":["16754858"],"confidence":"High","gaps":["Does not address human allotype-specific effects","Mechanism of over-trimming/destruction not structurally resolved"]},{"year":2006,"claim":"Linked a disease-associated polymorphism to enzymatic function by showing Lys528 substitutions reduce aminopeptidase activity.","evidence":"Site-directed mutagenesis, fluorogenic substrate assays, molecular modeling","pmids":["16513116"],"confidence":"Medium","gaps":["Structural explanation rests on modeling, not crystallography","Effect on physiological antigenic peptide trimming not tested"]},{"year":2006,"claim":"Identified NUCB2 as a calcium-dependent partner required for TNFR1 vesicular release, expanding the shedding machinery.","evidence":"Yeast two-hybrid, Co-IP in HUVEC, confocal, RNAi with TNFR1 release readout","pmids":["16407280"],"confidence":"Medium","gaps":["Single lab; reciprocal validation of the ternary mechanism limited","How NUCB2 binding couples to proteolytic cleavage unclear"]},{"year":2008,"claim":"Showed that ERAP1 reads internal substrate residues, not just the N-terminus, refining the substrate-recognition model.","evidence":"Systematic in vitro trimming with substituted peptides plus cavity modeling","pmids":["18987748"],"confidence":"Medium","gaps":["Structural cavity interpretation from modeling only","Single lab"]},{"year":2008,"claim":"Proposed RBMX as an additional regulator of TNFR1 release, though on weaker evidence.","evidence":"Single Co-IP and RNAi/overexpression with TNFR1 release readout","pmids":["18445477"],"confidence":"Low","gaps":["Single Co-IP without reciprocal validation","Functional link to ERAP1 catalytic role undefined","Nuclear hnRNP partner is mechanistically unexpected and unexplained"]},{"year":2011,"claim":"Provided the structural foundation by solving ERAP1 open and closed crystal structures, defining it as a gluzincin protease with large catalytic domain movements.","evidence":"X-ray crystallography in two states with K528R mutagenesis","pmids":["21508329"],"confidence":"High","gaps":["Conformational selection vs induced-fit not distinguished here","Allosteric activator binding sites not yet mapped"]},{"year":2011,"claim":"Established the length-dependent 'molecular ruler' mechanism by capturing ERAP1 with an extended groove and showing long substrates trigger a catalytic conformational change.","evidence":"ERAP1-bestatin crystal structure plus length-varied trimming assays","pmids":["21478864"],"confidence":"High","gaps":["In-solution dynamics of closure not directly observed in this study","Behavior on MHC-bound substrates not addressed"]},{"year":2011,"claim":"Demonstrated viral immune evasion targeting ERAP1, showing HCMV miR-US4-1 downregulates ERAP1 to impair antigen trimming and CTL killing.","evidence":"Viral infection, miRNA gain/loss-of-function, trimming and CTL assays","pmids":["21892175"],"confidence":"High","gaps":["Genome-wide miRNA target breadth not defined","In vivo relevance during natural infection not tested"]},{"year":2013,"claim":"Identified transcriptional control of ERAP1, showing p53 directly binds the locus to induce ERAP1 and raise MHC I expression.","evidence":"ChIP-seq, p53 siRNA, MHC I readouts, influenza infection model","pmids":["23965983"],"confidence":"High","gaps":["Other transcriptional regulators not addressed","Quantitative impact on the presented repertoire not measured"]},{"year":2014,"claim":"Explained why heterodimerization matters by showing ERAP2 allosterically improves ERAP1 substrate affinity and trimming, beyond simple enzyme mixing.","evidence":"Stabilized heterodimers, head-to-head trimming, enzymatic kinetics","pmids":["24928998"],"confidence":"High","gaps":["Structure of the heterodimer interface not resolved","Allosteric coupling mechanism not defined at atomic level"]},{"year":2015,"claim":"Connected ERAP1 to HLA-B27 biology and inflammatory T cell responses, linking trimming activity to ankylosing-spondylitis-relevant phenotypes.","evidence":"siRNA/pharmacological inhibition, FHC flow cytometry, KIR3DL2 reporter, Th17 readouts","pmids":["26130142"],"confidence":"Medium","gaps":["Causal peptide species driving FHC reduction not identified","Single lab"]},{"year":2015,"claim":"Showed ERAP1 tunes NK-cell inhibitory receptor engagement by modifying MHC ligand affinity, extending its role beyond T cell immunity.","evidence":"siRNA/inhibition, NK cytotoxicity, MHC I flow cytometry, peptide rescue","pmids":["25592150"],"confidence":"Medium","gaps":["Specific high-affinity ligands generated in vivo not enumerated","Single lab"]},{"year":2016,"claim":"Demonstrated ERAP1 specifically limits aberrant disulfide-linked HLA-B27 forms, sharpening the mechanistic link to spondyloarthritis.","evidence":"siRNA KD in HLA-B27 U937 cells, IP, isoelectric focusing, non-reducing immunoblot, flow cytometry","pmids":["27107845"],"confidence":"Medium","gaps":["Why HLA-B27 but not HLA-B18/B51 is affected not explained","Single lab"]},{"year":2016,"claim":"Showed heterodimers can trim MHC-bound precursors and stabilize peptide-MHC, supporting a peptide-editor model on loaded molecules.","evidence":"In vitro trimming of HLA-B*0801-bound extended peptides, thermal stability","pmids":["27514473"],"confidence":"Medium","gaps":["Slower MHC-bound trimming kinetics' physiological significance unclear","Single lab"]},{"year":2019,"claim":"Defined structural constraints of MHC-bound trimming, showing a minimum 14-residue length and how HLA-B*0801 accommodates extended N-termini.","evidence":"High-resolution crystallography of nested extended peptides, stability and trimming assays","pmids":["31601650"],"confidence":"High","gaps":["Generalizability across HLA allotypes not established","ERAP1-MHC docking geometry not visualized"]},{"year":2019,"claim":"Uncovered a non-peptidase signaling role in which ERAP1 displaces βTrCP from USP47 to enhance Hedgehog/Gli activity and tumor growth.","evidence":"Co-IP of ternary complex, ubiquitination and Gli reporter assays, KD/inhibition, in vivo tumor models","pmids":["31341163"],"confidence":"Medium","gaps":["Whether this requires aminopeptidase activity not resolved","Single lab"]},{"year":2021,"claim":"Unified the structural mechanism by showing in solution that long substrates and allosteric activators drive ERAP1 domain closure coupled to active-site reconfiguration, explaining K528R disease association.","evidence":"SAXS, crystallography, crosslinking-MS, enzymatic assays with allosteric modulators","pmids":["34489420"],"confidence":"High","gaps":["Alternate C-terminal binding site occupancy under physiological conditions unclear","Dynamics of heterodimer closure not addressed"]},{"year":2021,"claim":"Linked an ERAP1 risk haplotype to autoimmune disease causation by showing efficient generation of an HLA-C*06:02-restricted psoriasis autoantigen.","evidence":"ERAP1-modified/KO cell lines, psoriatic autoreactive TCR activation, HLA-C flow cytometry, recombinant variant trimming","pmids":["34580106"],"confidence":"Medium","gaps":["In vivo demonstration in patients not performed","Single lab"]},{"year":2021,"claim":"Confirmed a second viral evasion route via HCMV miR-UL112-5p targeting the ERAP1 3'UTR, with a host SNP that escapes targeting.","evidence":"3'UTR reporter, genotyped fibroblasts, trimming and CTL assays, seropositivity analysis","pmids":["28746870"],"confidence":"Medium","gaps":["Population-level impact of rs17481334 on HCMV control not established","Single lab"]},{"year":2022,"claim":"Identified a metabolic hepatokine function in which secreted ERAP1 binds ADRB2 and reduces USP33-mediated deubiquitination to impair muscle insulin sensitivity.","evidence":"Hepatic OE/KD in mice, serum ERAP1, ERAP1-ADRB2 Co-IP, ubiquitination and insulin signaling analysis","pmids":["35192681"],"confidence":"Medium","gaps":["Whether secreted ERAP1's aminopeptidase activity is required not resolved","Single lab; human relevance untested"]},{"year":2018,"claim":"Showed ERAP1 loss produces ankylosing-spondylitis-like skeletal disease, dysbiosis, and regulatory T cell deficits, tying the enzyme to disease pathophysiology in vivo.","evidence":"ERAP1 KO mice, µCT, histology, microbiota cross-fostering, immune flow cytometry","pmids":["30127455"],"confidence":"Medium","gaps":["Causal peptide/antigenic basis of skeletal phenotype undefined","Single lab"]},{"year":null,"claim":"It remains unresolved how ERAP1's multiple non-canonical functions (receptor shedding, Hedgehog modulation, ADRB2-directed metabolic signaling) mechanistically relate to its aminopeptidase activity and whether they share a common biochemical basis.","evidence":"No single study reconciles the peptidase and signaling/shedding roles","pmids":[],"confidence":"Low","gaps":["Catalytic dependence of the Hedgehog and ADRB2 functions untested","No structure of ERAP1 bound to TNFR1, ADRB2, or USP47","Mechanism linking aminopeptidase activity to ectodomain shedding undefined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,1,2,5,8]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,5,13,19]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[12]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[0,5]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[8,9]},{"term_id":"GO:0005886","term_label":"plasma 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Peptide trimming is essential to customize longer precursor peptides to fit them to the correct length required for presentation on MHC class I molecules. Strongly prefers substrates 9-16 residues long. Rapidly degrades 13-mer to a 9-mer and then stops. Preferentially hydrolyzes the residue Leu and peptides with a hydrophobic C-terminus, while it has weak activity toward peptides with charged C-terminus. May play a role in the inactivation of peptide hormones. 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RETICULUM AMINOPEPTIDASE 1; ERAP1","url":"https://www.omim.org/entry/606832"},{"mim_id":"177900","title":"PSORIASIS 1, SUSCEPTIBILITY TO; PSORS1","url":"https://www.omim.org/entry/177900"},{"mim_id":"145500","title":"HYPERTENSION, ESSENTIAL","url":"https://www.omim.org/entry/145500"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Cytosol","reliability":"Approved"},{"location":"Plasma membrane","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in 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presentation.\",\n      \"method\": \"Co-localization by immunofluorescence, physical association by co-immunoprecipitation, in vitro peptide digestion assays, cellular antigen presentation assays\",\n      \"journal\": \"Nature immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — reciprocal Co-IP establishing heterodimer, in vitro enzymatic assay, and in vivo antigen presentation readout in a single study; findings on concerted trimming replicated in subsequent work\",\n      \"pmids\": [\"15908954\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"X-ray crystal structures of human ERAP1 in open and closed conformations reveal it is a zinc-metallopeptidase with HEXXH-(X)18-E zinc-binding and GAMEN motifs characteristic of the gluzincin protease family; extensive domain movements including active-site closure are observed along the catalytic path, and the K528R disease-associated variant shows altered peptide processing characteristics possibly related to impaired interdomain interactions.\",\n      \"method\": \"X-ray crystallography (open and closed state structures); site-directed mutagenesis of K528R; in vitro peptide processing assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structures with functional mutagenesis validation; independently corroborated by multiple subsequent structural studies\",\n      \"pmids\": [\"21508329\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"X-ray crystal structure of human ERAP1 bound to bestatin reveals an open conformation with a large interior compartment and an extended groove from the catalytic center that accommodates long peptides; structural and biochemical analyses demonstrate a length-dependent trimming mechanism whereby binding of long (but not short) substrates induces a conformational change reorienting a key catalytic residue toward the active site.\",\n      \"method\": \"X-ray crystallography (ERAP1–bestatin complex); biochemical trimming assays with peptides of varying length\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus biochemical mechanistic validation in a single rigorous study; the length-dependent conformational change mechanism was subsequently supported by additional structural and SAXS studies\",\n      \"pmids\": [\"21478864\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"ERAP1 (ARTS-1) is a type II integral membrane aminopeptidase that physically binds the extracellular domain of TNFR1 and promotes TNFR1 ectodomain shedding; overexpression increases TNFR1 shedding while antisense knockdown decreases it; ARTS-1 does not bind TNFR2 and does not possess sheddase activity itself.\",\n      \"method\": \"Yeast two-hybrid screen; co-immunoprecipitation in human pulmonary epithelial and endothelial cells; overexpression and antisense knockdown with TNFR1 shedding quantification; in vitro aminopeptidase activity assay\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP in two cell types, functional gain- and loss-of-function experiments, multiple orthogonal methods in one study\",\n      \"pmids\": [\"12189246\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"ERAP1 (ARTS-1) directly binds IL-6Rα and is required for constitutive IL-6Rα shedding; ARTS-1 catalytic activity is necessary for constitutive shedding; knockout cells lack basal IL-6Rα shedding, and overexpression increases it.\",\n      \"method\": \"Reciprocal co-immunoprecipitation; ARTS-1 overexpression and knockout cell lines; shedding quantification; catalytic activity requirement demonstrated by enzymatic inhibition\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, KO cells with defined shedding phenotype, catalytic dependency demonstrated; multiple orthogonal methods\",\n      \"pmids\": [\"12748171\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"In mice, ERAP1 is the major enzyme trimming precursor peptides in the endoplasmic reticulum; loss of ERAP1 markedly shifts the hierarchy of immunodominance in viral infections, generating some antigenic peptides while destroying others by over-trimming to sub-optimal lengths, demonstrating that ERAP1 trimming and resultant peptide-MHC abundance are dominant factors establishing immunodominance.\",\n      \"method\": \"ERAP1 knockout mice; viral infection model (influenza); CD8+ T cell response hierarchy measured by peptide-MHC tetramer staining and cytotoxicity assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — clean KO with specific immunodominance phenotype, replicated across multiple viral epitopes in a single rigorous study\",\n      \"pmids\": [\"16754858\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"ERAP1 trimming efficiency is strongly influenced by internal (non-N-terminal) residues of the peptide substrate; positively charged or hydrophobic residues at internal positions increase trimming rates by up to 100-fold for single substitutions and >40,000-fold for multiple substitutions, indicating ERAP1 recognizes the full length of its substrate via a large negatively charged internal cavity adjacent to the active site.\",\n      \"method\": \"Systematic in vitro peptide trimming assays with collections of peptide substrates; molecular modeling of ERAP1 cavity\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — rigorous in vitro enzymatic assay with systematic substrate variation; molecular modeling supports but does not independently validate the structural explanation; single lab\",\n      \"pmids\": [\"18987748\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"The Lys528Arg polymorphism of ERAP1 (A-LAP) significantly reduces enzymatic aminopeptidase activity; site-directed mutagenesis of Lys528 to multiple amino acids (Ala, Met, His, Arg) all caused decreased activity, and molecular modeling suggests Lys528 is near the substrate pocket entrance and maintains its optimal structure.\",\n      \"method\": \"Site-directed mutagenesis; in vitro aminopeptidase activity assays with fluorogenic substrates; molecular modeling\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro mutagenesis and enzymatic assay, single lab; molecular modeling is supportive but not crystallographic\",\n      \"pmids\": [\"16513116\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"ERAP1 (PILS-AP) is a signal-sequence-bearing M1 family zinc-dependent aminopeptidase; when expressed as a GFP fusion protein it localizes to intracellular vesicles in COS-7 and BHK cells; it exhibits selective leucyl (and to a lesser extent methionyl) aminopeptidase activity that is inhibited by chelators of bivalent cations but, unusually, not by puromycin.\",\n      \"method\": \"GFP fusion protein live-cell imaging (subcellular localization); expression in Sf9 insect cells; in vitro enzymatic activity assay with aminoacyl β-naphthylamide substrates; inhibitor profiling\",\n      \"journal\": \"European journal of biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — direct localization by live imaging tied to enzymatic characterization; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"10824104\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"ERAP1 (ARTS-1) forms a calcium-dependent complex with nucleobindin 2 (NUCB2) via NUCB2's helix-loop-helix domains binding the ARTS-1 extracellular domain; this NUCB2·ARTS-1 complex associates with a subset of cellular TNFR1 within intracytoplasmic vesicles, and both proteins are required for constitutive release of full-length TNFR1 in exosome-like vesicles and for inducible proteolytic cleavage of soluble TNFR1 ectodomains.\",\n      \"method\": \"Yeast two-hybrid screen; co-immunoprecipitation in HUVEC; confocal microscopy; RNA interference knockdown of NUCB2 and ARTS-1 with TNFR1 release quantification\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus RNAi loss-of-function with specific vesicle-release phenotype and confocal localization; single lab\",\n      \"pmids\": [\"16407280\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"ERAP1 (ARTS-1) physically associates with RBMX (a heterogeneous nuclear ribonucleoprotein) as shown by co-immunoprecipitation; RNAi knockdown of RBMX reduces both constitutive TNFR1 exosome-like vesicle release and IL-1β-induced proteolytic cleavage of TNFR1 ectodomains, while RBMX overexpression has the opposite effect.\",\n      \"method\": \"Co-immunoprecipitation; RNA interference; overexpression with TNFR1 release quantification\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP and RNAi with functional readout; single lab, single method for binding\",\n      \"pmids\": [\"18445477\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"HCMV miR-US4-1 specifically downregulates ERAP1 expression during viral infection, thereby inhibiting trimming of HCMV-derived peptide precursors and reducing susceptibility of infected cells to HCMV-specific cytotoxic T lymphocytes, constituting a viral miRNA-based CTL-evasion mechanism targeting the MHC class I antigen-processing pathway.\",\n      \"method\": \"Viral infection of cell lines; miRNA overexpression and knockdown; ERAP1 protein/mRNA quantification; peptide trimming assay; CTL killing assay\",\n      \"journal\": \"Nature immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (miRNA functional assay, trimming assay, CTL killing) in a single rigorous study; published in high-tier journal with thorough mechanistic follow-up\",\n      \"pmids\": [\"21892175\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"p53 directly upregulates ERAP1 expression by binding to a cognate response element in the ERAP1 gene, thereby increasing MHC class I surface expression; silencing p53 decreases ERAP1 protein and MHC class I expression; during H1N1 influenza infection, virus-activated p53 leads to ERAP1 upregulation and increased MHC class I expression.\",\n      \"method\": \"Chromatin immunoprecipitation sequencing (ChIP-seq) identifying p53 binding at ERAP1 locus; gene expression analysis; p53 siRNA knockdown; viral infection model\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — ChIP-seq identifying direct promoter binding plus loss-of-function with defined MHC I phenotype; orthogonal validation in infection model\",\n      \"pmids\": [\"23965983\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Stabilized ERAP1-ERAP2 heterodimers produce mature MHC class I epitopes more efficiently than a mixture of the two enzymes unable to dimerize; physical interaction with ERAP2 allosterically changes basic enzymatic parameters of ERAP1 and improves its substrate-binding affinity, indicating that dimerization creates complexes with superior peptide-trimming efficacy.\",\n      \"method\": \"Production of stabilized ERAP1-ERAP2 heterodimers; in vitro peptide-trimming assays comparing heterodimer vs. non-dimerizing enzyme mixtures; enzymatic kinetics measurements (Km, kcat)\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro reconstitution with stabilized heterodimers, enzymatic kinetics, and head-to-head comparison; findings corroborated by independent study (PMID 27514473)\",\n      \"pmids\": [\"24928998\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"ERAP1-ERAP2 heterodimers can trim MHC class I-bound precursor peptides to their correct final lengths (albeit more slowly than free precursors), and such trimming increases the conformational stability of MHC I/peptide complexes, supporting a model of ERAP1/2 as peptide editors acting on MHC I-bound substrates.\",\n      \"method\": \"In vitro trimming assay using ERAP1/2 heterodimers with free and HLA-B*0801-bound N-terminally extended peptides; thermal stability measurements of MHC I/peptide complexes\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstitution assay with heterodimers and MHC-bound peptides; single lab, novel finding of MHC-bound trimming\",\n      \"pmids\": [\"27514473\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"ERAP1 silencing or pharmacological inhibition in HLA-B27-expressing antigen-presenting cells downregulates surface HLA-B27 free heavy chain (FHC) expression, reduces IL-2 production by KIR3DL2-reporter cells, and suppresses Th17 expansion and IL-17A secretion by AS CD4+ T cells; AS-protective ERAP1 variants K528R and Q730E are associated with reduced FHC expression on patient monocytes.\",\n      \"method\": \"siRNA knockdown; pharmacological ERAP1 inhibition; flow cytometry (surface FHC and MHC I expression); KIR3DL2 reporter co-culture; Th17 intracellular cytokine staining; ELISA\",\n      \"journal\": \"Annals of the rheumatic diseases\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean knockdown and pharmacological inhibition with multiple downstream cellular readouts; single lab\",\n      \"pmids\": [\"26130142\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"ERAP1 knockdown increases accumulation of HLA-B27 on the cell surface including disulfide-linked dimers but has no effect on HLA-B18 or HLA-B51, demonstrating that normal ERAP1 levels specifically reduce aberrant and disulfide-linked forms of HLA-B27 in monocytes.\",\n      \"method\": \"ERAP1 siRNA knockdown in HLA-B27-expressing U937 monocytic cells; immunoprecipitation; isoelectric focusing; immunoblotting (non-reducing gels); flow cytometry with HLA-B27-specific antibodies\",\n      \"journal\": \"Molecular immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple biochemical methods with clean KD and specific HLA-B27 phenotype; single lab\",\n      \"pmids\": [\"27107845\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"ERAP1 binds the deubiquitylase USP47, displaces USP47-associated βTrCP (the substrate-receptor subunit of SCFβTrCP ubiquitin ligase), and promotes βTrCP degradation; this results in modulation of Gli transcription factors and enhancement of Hedgehog pathway activity; genetic or pharmacological inhibition of ERAP1 suppresses Hh-dependent tumor growth in vitro and in vivo.\",\n      \"method\": \"Co-immunoprecipitation (ERAP1-USP47-βTrCP); ubiquitination assays; Gli reporter assays; ERAP1 genetic knockdown and pharmacological inhibition; in vivo tumor growth assays (mouse models)\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP establishing ternary complex, functional reporter assay, in vivo tumor model; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"31341163\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Genetic or pharmacological inhibition of ERAP1 on human tumor cell lines perturbs engagement of multiple classes of inhibitory NK cell receptors (KIR by classical pMHC-I; CD94-NKG2A by nonclassical pMHC-I), leading to NK cell killing; the protective effect of pMHC-I could be restored by addition of high-affinity peptides, indicating ERAP1 positively modifies the affinity of natural MHC ligands.\",\n      \"method\": \"siRNA knockdown and pharmacological inhibition of ERAP1; NK cell cytotoxicity assays; flow cytometry of MHC-I surface expression; peptide rescue experiments; killing of autologous/allogeneic lymphoblastoid cell lines\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KD and pharmacological inhibition with multiple NK receptor functional readouts and peptide rescue experiment; single lab\",\n      \"pmids\": [\"25592150\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"ERAP1-mediated trimming of MHC I-bound precursor peptides requires peptides of at least 14 amino acids in length; N-terminal residue extensions protrude out of the HLA-B*0801 A pocket while the core peptide adopts the standard bound conformation; HLA-B*0801 residue 62 is critical for opening the A pocket to accommodate extended peptides.\",\n      \"method\": \"X-ray crystallography of HLA-B*0801 complexes with nested N-terminally extended peptides (1.40–1.65 Å); thermal stability assays; in vitro ERAP1 trimming assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — high-resolution crystal structures plus biochemical trimming assay defining minimal length requirement for MHC-bound trimming; multiple orthogonal methods\",\n      \"pmids\": [\"31601650\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Solution SAXS and X-ray crystallography demonstrate that ERAP1 undergoes domain closure in solution upon binding of long peptide substrates and allosteric activators; structural reconfigurations of the ERAP1 active site are physically linked to domain closure; chemical crosslinking localizes alternate C-terminal binding sites; the K528R polymorphism disease association is mechanistically explained by its role in domain closure dynamics.\",\n      \"method\": \"Small-angle X-ray scattering (SAXS) in solution; X-ray crystallography; chemical crosslinking with mass spectrometry; enzymatic assays with allosteric modulators\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — SAXS plus crystallography plus crosslinking-MS, multiple orthogonal structural methods with enzymatic validation; single comprehensive study\",\n      \"pmids\": [\"34489420\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"HCMV miR-UL112-5p targets the ERAP1 3′ UTR to inhibit ERAP1 expression and processing of the HCMV pp65495-503 peptide, thereby reducing CTL lysis of infected cells; a naturally occurring rs17481334 G variant in the ERAP1 3′ UTR prevents miR-UL112-5p binding and preserves ERAP1 expression, making GG homozygous fibroblasts more efficient at viral antigen trimming and more susceptible to CTL killing.\",\n      \"method\": \"miRNA target-site validation (3′ UTR reporter assay); ERAP1 RNA and protein quantification in genotyped fibroblasts; in vitro trimming assay; CTL cytotoxicity assay; HCMV seropositivity analysis\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — 3′ UTR reporter plus functional trimming and CTL assays in genotyped cells; single lab but multiple orthogonal methods\",\n      \"pmids\": [\"28746870\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"In psoriasis, ERAP1 generates the causative HLA-C*06:02-restricted melanocyte autoantigen by trimming N-terminally elongated peptide precursors; an ERAP1 risk haplotype produces the autoantigen much more efficiently and increases HLA-C expression and stimulation of a psoriatic autoreactive TCR significantly more than a protective haplotype; HLA-C surface expression decreases more upon ERAP1 knockout than overall HLA class I.\",\n      \"method\": \"ERAP1 genetically modified cell lines; TCR activation assay with psoriatic autoreactive TCR; flow cytometry of HLA-C surface expression; ERAP1 knockout; in vitro peptide trimming with recombinant ERAP1 variants\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional TCR activation assay with KO cells and allotype-defined recombinant ERAP1 variants; single lab; multiple methods\",\n      \"pmids\": [\"34580106\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"ERAP1 functions as an inflammation-induced hepatokine: hepatic ERAP1 overexpression attenuates systemic and skeletal muscle insulin sensitivity while knockdown has the opposite effect; mechanistically, secreted ERAP1 interacts with β2 adrenergic receptor (ADRB2) and reduces its expression by decreasing USP33-mediated deubiquitination, thereby disrupting ADRB2-stimulated insulin signaling in skeletal muscle.\",\n      \"method\": \"Hepatic ERAP1 overexpression and knockdown in mice (HFD model); serum ERAP1 measurement; co-immunoprecipitation of ERAP1 with ADRB2; ubiquitination assay; ADRB2 protein quantification; insulin signaling pathway analysis in skeletal muscle\",\n      \"journal\": \"Diabetes\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo gain/loss-of-function with Co-IP identifying ERAP1-ADRB2 interaction and ubiquitination mechanism; single lab, novel non-immune function\",\n      \"pmids\": [\"35192681\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"ERAP1 deletion in ERAP1−/− mice leads to development of hallmark skeletal features of ankylosing spondylitis (spinal ankylosis, osteoporosis, spinal inflammation), spontaneous intestinal dysbiosis, and increased susceptibility to DSS-induced colitis; these mice have reduced Tr1-like regulatory T cells and tolerogenic dendritic cells while maintaining normal Foxp3+ Treg numbers.\",\n      \"method\": \"ERAP1 knockout mice; µCT imaging; histology; microbiota transfer (cross-fostering); flow cytometry of immune cell populations\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO with specific skeletal and immunological phenotypes using multiple readouts; single lab\",\n      \"pmids\": [\"30127455\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ERAP1 is an ER-resident zinc-metallopeptidase (M1/gluzincin family) that trims N-terminally extended peptide precursors for loading onto MHC class I molecules via a length-dependent, allosterically regulated mechanism involving domain closure upon long-substrate binding; it forms catalytically superior heterodimers with ERAP2; it also promotes TNFR1 and IL-6Rα ectodomain shedding via direct receptor binding, regulates HLA-B27 free heavy chain levels and NK/T cell responses, is transcriptionally induced by p53, is targeted for immune evasion by HCMV miRNAs, interacts with USP47/βTrCP to modulate Hedgehog signaling, and functions as a hepatokine that impairs skeletal muscle insulin sensitivity through ADRB2-USP33 deubiquitination.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ERAP1 is an endoplasmic-reticulum-resident, zinc-dependent M1/gluzincin aminopeptidase that shapes the MHC class I peptide repertoire by trimming N-terminally extended precursor peptides to their mature lengths for antigen presentation [#0, #5]. Crystallographic and solution-scattering analyses define a multidomain enzyme bearing the HEXXH-(X)18-E zinc-binding and GAMEN motifs that cycles between open and closed conformations; binding of long peptide substrates or allosteric activators drives active-site closure and reorients a key catalytic residue, providing a structural basis for its length-dependent 'molecular ruler' trimming and for recognition of internal substrate residues via a large interior cavity [#1, #2, #6, #20]. ERAP1 partners with ERAP2 to form ER heterodimers whose dimerization allosterically enhances substrate affinity and trimming efficacy beyond either enzyme alone, and it can edit precursor peptides while bound to MHC class I, requiring a minimum substrate length to engage MHC-bound peptides [#0, #13, #14, #19]. Through this trimming activity ERAP1 establishes CD8+ T cell immunodominance hierarchies, sets surface levels and conformational stability of MHC class I (including disulfide-linked HLA-B27 free heavy chains), and tunes NK-cell inhibitory receptor engagement by modifying the affinity of natural MHC ligands [#5, #15, #16, #18]; an ERAP1 risk haplotype efficiently generates an HLA-C*06:02-restricted melanocyte autoantigen in psoriasis [#22]. ERAP1 expression is directly induced by p53 and is suppressed by HCMV miRNAs (miR-US4-1 and miR-UL112-5p) as a CTL-evasion strategy [#11, #12, #21]. Beyond antigen processing, ERAP1 (originally identified as ARTS-1) binds the ectodomains of TNFR1 and IL-6Rα to promote their shedding [#3, #4], modulates Hedgehog signaling by displacing βTrCP from USP47 [#17], and acts as a hepatokine that impairs skeletal-muscle insulin sensitivity by binding ADRB2 and reducing its USP33-mediated deubiquitination [#23]. ERAP1-deficient mice develop ankylosing-spondylitis-like skeletal disease and intestinal dysbiosis [#24].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Established ERAP1's basic biochemical identity, answering whether the protein is an enzyme and where it acts.\",\n      \"evidence\": \"GFP-fusion live-cell imaging and in vitro aminopeptidase assays with inhibitor profiling\",\n      \"pmids\": [\"10824104\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Vesicular localization in COS-7/BHK does not pinpoint the ER residence later established\", \"Substrate specificity defined only with model aminoacyl substrates, not antigenic peptides\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Revealed an antigen-processing-independent role by showing ERAP1 binds TNFR1 and promotes its ectodomain shedding, raising the question of how an aminopeptidase regulates receptor shedding.\",\n      \"evidence\": \"Yeast two-hybrid, reciprocal Co-IP in two cell types, gain/loss-of-function shedding assays\",\n      \"pmids\": [\"12189246\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"ERAP1 itself lacks sheddase activity, so the molecular link to the actual protease is unresolved\", \"Selectivity for TNFR1 over TNFR2 mechanism not explained\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Extended the shedding role to IL-6Rα and showed catalytic activity is required, distinguishing this function from passive receptor binding.\",\n      \"evidence\": \"Reciprocal Co-IP, KO cells, enzymatic inhibition of shedding\",\n      \"pmids\": [\"12748171\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How aminopeptidase activity mechanistically enables shedding is undefined\", \"Physiological substrates cleaved during shedding not identified\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Defined ERAP1's central antigen-processing function by showing it forms ER heterodimers with ERAP2 to concertedly trim MHC I peptide precursors.\",\n      \"evidence\": \"Co-localization, Co-IP, in vitro digestion and cellular antigen presentation assays\",\n      \"pmids\": [\"15908954\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of the heterodimer not resolved here\", \"Quantitative contribution of each enzyme to the repertoire unclear\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Demonstrated in vivo that ERAP1 trimming dominantly shapes CD8+ T cell immunodominance, establishing physiological consequence of trimming.\",\n      \"evidence\": \"ERAP1 knockout mice, influenza infection, tetramer staining and cytotoxicity\",\n      \"pmids\": [\"16754858\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Does not address human allotype-specific effects\", \"Mechanism of over-trimming/destruction not structurally resolved\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Linked a disease-associated polymorphism to enzymatic function by showing Lys528 substitutions reduce aminopeptidase activity.\",\n      \"evidence\": \"Site-directed mutagenesis, fluorogenic substrate assays, molecular modeling\",\n      \"pmids\": [\"16513116\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural explanation rests on modeling, not crystallography\", \"Effect on physiological antigenic peptide trimming not tested\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identified NUCB2 as a calcium-dependent partner required for TNFR1 vesicular release, expanding the shedding machinery.\",\n      \"evidence\": \"Yeast two-hybrid, Co-IP in HUVEC, confocal, RNAi with TNFR1 release readout\",\n      \"pmids\": [\"16407280\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; reciprocal validation of the ternary mechanism limited\", \"How NUCB2 binding couples to proteolytic cleavage unclear\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Showed that ERAP1 reads internal substrate residues, not just the N-terminus, refining the substrate-recognition model.\",\n      \"evidence\": \"Systematic in vitro trimming with substituted peptides plus cavity modeling\",\n      \"pmids\": [\"18987748\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural cavity interpretation from modeling only\", \"Single lab\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Proposed RBMX as an additional regulator of TNFR1 release, though on weaker evidence.\",\n      \"evidence\": \"Single Co-IP and RNAi/overexpression with TNFR1 release readout\",\n      \"pmids\": [\"18445477\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single Co-IP without reciprocal validation\", \"Functional link to ERAP1 catalytic role undefined\", \"Nuclear hnRNP partner is mechanistically unexpected and unexplained\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Provided the structural foundation by solving ERAP1 open and closed crystal structures, defining it as a gluzincin protease with large catalytic domain movements.\",\n      \"evidence\": \"X-ray crystallography in two states with K528R mutagenesis\",\n      \"pmids\": [\"21508329\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Conformational selection vs induced-fit not distinguished here\", \"Allosteric activator binding sites not yet mapped\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Established the length-dependent 'molecular ruler' mechanism by capturing ERAP1 with an extended groove and showing long substrates trigger a catalytic conformational change.\",\n      \"evidence\": \"ERAP1-bestatin crystal structure plus length-varied trimming assays\",\n      \"pmids\": [\"21478864\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In-solution dynamics of closure not directly observed in this study\", \"Behavior on MHC-bound substrates not addressed\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Demonstrated viral immune evasion targeting ERAP1, showing HCMV miR-US4-1 downregulates ERAP1 to impair antigen trimming and CTL killing.\",\n      \"evidence\": \"Viral infection, miRNA gain/loss-of-function, trimming and CTL assays\",\n      \"pmids\": [\"21892175\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Genome-wide miRNA target breadth not defined\", \"In vivo relevance during natural infection not tested\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identified transcriptional control of ERAP1, showing p53 directly binds the locus to induce ERAP1 and raise MHC I expression.\",\n      \"evidence\": \"ChIP-seq, p53 siRNA, MHC I readouts, influenza infection model\",\n      \"pmids\": [\"23965983\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Other transcriptional regulators not addressed\", \"Quantitative impact on the presented repertoire not measured\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Explained why heterodimerization matters by showing ERAP2 allosterically improves ERAP1 substrate affinity and trimming, beyond simple enzyme mixing.\",\n      \"evidence\": \"Stabilized heterodimers, head-to-head trimming, enzymatic kinetics\",\n      \"pmids\": [\"24928998\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structure of the heterodimer interface not resolved\", \"Allosteric coupling mechanism not defined at atomic level\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Connected ERAP1 to HLA-B27 biology and inflammatory T cell responses, linking trimming activity to ankylosing-spondylitis-relevant phenotypes.\",\n      \"evidence\": \"siRNA/pharmacological inhibition, FHC flow cytometry, KIR3DL2 reporter, Th17 readouts\",\n      \"pmids\": [\"26130142\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal peptide species driving FHC reduction not identified\", \"Single lab\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Showed ERAP1 tunes NK-cell inhibitory receptor engagement by modifying MHC ligand affinity, extending its role beyond T cell immunity.\",\n      \"evidence\": \"siRNA/inhibition, NK cytotoxicity, MHC I flow cytometry, peptide rescue\",\n      \"pmids\": [\"25592150\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific high-affinity ligands generated in vivo not enumerated\", \"Single lab\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Demonstrated ERAP1 specifically limits aberrant disulfide-linked HLA-B27 forms, sharpening the mechanistic link to spondyloarthritis.\",\n      \"evidence\": \"siRNA KD in HLA-B27 U937 cells, IP, isoelectric focusing, non-reducing immunoblot, flow cytometry\",\n      \"pmids\": [\"27107845\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Why HLA-B27 but not HLA-B18/B51 is affected not explained\", \"Single lab\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Showed heterodimers can trim MHC-bound precursors and stabilize peptide-MHC, supporting a peptide-editor model on loaded molecules.\",\n      \"evidence\": \"In vitro trimming of HLA-B*0801-bound extended peptides, thermal stability\",\n      \"pmids\": [\"27514473\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Slower MHC-bound trimming kinetics' physiological significance unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Defined structural constraints of MHC-bound trimming, showing a minimum 14-residue length and how HLA-B*0801 accommodates extended N-termini.\",\n      \"evidence\": \"High-resolution crystallography of nested extended peptides, stability and trimming assays\",\n      \"pmids\": [\"31601650\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Generalizability across HLA allotypes not established\", \"ERAP1-MHC docking geometry not visualized\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Uncovered a non-peptidase signaling role in which ERAP1 displaces βTrCP from USP47 to enhance Hedgehog/Gli activity and tumor growth.\",\n      \"evidence\": \"Co-IP of ternary complex, ubiquitination and Gli reporter assays, KD/inhibition, in vivo tumor models\",\n      \"pmids\": [\"31341163\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether this requires aminopeptidase activity not resolved\", \"Single lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Unified the structural mechanism by showing in solution that long substrates and allosteric activators drive ERAP1 domain closure coupled to active-site reconfiguration, explaining K528R disease association.\",\n      \"evidence\": \"SAXS, crystallography, crosslinking-MS, enzymatic assays with allosteric modulators\",\n      \"pmids\": [\"34489420\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Alternate C-terminal binding site occupancy under physiological conditions unclear\", \"Dynamics of heterodimer closure not addressed\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Linked an ERAP1 risk haplotype to autoimmune disease causation by showing efficient generation of an HLA-C*06:02-restricted psoriasis autoantigen.\",\n      \"evidence\": \"ERAP1-modified/KO cell lines, psoriatic autoreactive TCR activation, HLA-C flow cytometry, recombinant variant trimming\",\n      \"pmids\": [\"34580106\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo demonstration in patients not performed\", \"Single lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Confirmed a second viral evasion route via HCMV miR-UL112-5p targeting the ERAP1 3'UTR, with a host SNP that escapes targeting.\",\n      \"evidence\": \"3'UTR reporter, genotyped fibroblasts, trimming and CTL assays, seropositivity analysis\",\n      \"pmids\": [\"28746870\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Population-level impact of rs17481334 on HCMV control not established\", \"Single lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identified a metabolic hepatokine function in which secreted ERAP1 binds ADRB2 and reduces USP33-mediated deubiquitination to impair muscle insulin sensitivity.\",\n      \"evidence\": \"Hepatic OE/KD in mice, serum ERAP1, ERAP1-ADRB2 Co-IP, ubiquitination and insulin signaling analysis\",\n      \"pmids\": [\"35192681\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether secreted ERAP1's aminopeptidase activity is required not resolved\", \"Single lab; human relevance untested\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showed ERAP1 loss produces ankylosing-spondylitis-like skeletal disease, dysbiosis, and regulatory T cell deficits, tying the enzyme to disease pathophysiology in vivo.\",\n      \"evidence\": \"ERAP1 KO mice, µCT, histology, microbiota cross-fostering, immune flow cytometry\",\n      \"pmids\": [\"30127455\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal peptide/antigenic basis of skeletal phenotype undefined\", \"Single lab\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how ERAP1's multiple non-canonical functions (receptor shedding, Hedgehog modulation, ADRB2-directed metabolic signaling) mechanistically relate to its aminopeptidase activity and whether they share a common biochemical basis.\",\n      \"evidence\": \"No single study reconciles the peptidase and signaling/shedding roles\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Catalytic dependence of the Hedgehog and ADRB2 functions untested\", \"No structure of ERAP1 bound to TNFR1, ADRB2, or USP47\", \"Mechanism linking aminopeptidase activity to ectodomain shedding undefined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 1, 2, 5, 8]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 5, 13, 19]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [12]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [0, 5]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [8, 9]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [3, 4]},\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [23]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [0, 5, 15, 18]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 5, 13]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [3, 4, 17, 23]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [15, 22, 24]}\n    ],\n    \"complexes\": [\n      \"ERAP1-ERAP2 heterodimer\"\n    ],\n    \"partners\": [\n      \"ERAP2\",\n      \"TNFR1\",\n      \"IL6R\",\n      \"NUCB2\",\n      \"USP47\",\n      \"BTRC\",\n      \"ADRB2\",\n      \"USP33\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}