{"gene":"MCFD2","run_date":"2026-06-10T02:59:50","timeline":{"discoveries":[{"year":2005,"finding":"LMAN1 and MCFD2 form a 1:1 stoichiometric complex in the early secretory pathway, and both proteins interact with coagulation factor VIII (at the B domain) via calcium-dependent protein-protein interactions, independent of factor VIII glycosylation state. MCFD2 is retained in the ER through its interaction with LMAN1, and MCFD2 interaction with FVIII is independent of LMAN1-MCFD2 complex formation.","method":"Cross-linking immunoprecipitation, co-immunoprecipitation, Western blot, stoichiometry analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP with cross-linking, multiple orthogonal methods, foundational study replicated by subsequent work","pmids":["15886209"],"is_preprint":false},{"year":2005,"finding":"Missense mutations in MCFD2 (e.g., I136T) result in a low but detectable level of residual LMAN1-MCFD2 complex, suggesting complete loss of the complex is not required for clinically significant reduction in FV and FVIII secretion.","method":"Immunoprecipitation and Western blot of patient-derived lymphoblasts","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — patient-derived cells, Co-IP and Western blot, single lab","pmids":["16304051"],"is_preprint":false},{"year":2006,"finding":"MCFD2 is dispensable for binding of cathepsin Z and cathepsin C to ERGIC-53, demonstrating cargo selectivity: MCFD2 is specifically required for recruitment of coagulation factors V and VIII but not for glycoprotein cargo in general. In the absence of ERGIC-53, MCFD2 is secreted rather than retained.","method":"siRNA knockdown, yellow fluorescent protein fragment complementation assay (in vivo cargo binding)","journal":"Traffic (Copenhagen, Denmark)","confidence":"High","confidence_rationale":"Tier 2 / Strong — siRNA knockdown combined with YFP-fragment complementation, two orthogonal methods establishing cargo selectivity","pmids":["17010120"],"is_preprint":false},{"year":2007,"finding":"Deletion of the C-terminal 3 residues (ΔS-L-Q) of MCFD2 impairs binding to ERGIC-53 due to modification of the 3D structure of MCFD2, establishing that the C-terminus is structurally critical for the ERGIC-53/MCFD2 interaction.","method":"Biochemical binding assay, structural analysis of mutant MCFD2","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — patient mutation, biochemical and structural analysis, single lab","pmids":["17971482"],"is_preprint":false},{"year":2007,"finding":"MCFD2 interaction with ERGIC-53 enhances the sugar-binding ability of ERGIC-53 (specifically for high-mannose oligosaccharides, especially M8B). F5F8D patient MCFD2 missense mutants show 3–4 orders of magnitude lower affinity for ERGIC-53 by surface plasmon resonance. The MCFD2-ERGIC-53 interaction is calcium-dependent, becoming significantly weaker below 0.2 mM calcium.","method":"Flow cytometry binding assay, surface plasmon resonance, endo H treatment","journal":"Blood","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro SPR binding assay combined with cell-based flow cytometry, multiple orthogonal methods, calcium-dependence quantified","pmids":["18056485"],"is_preprint":false},{"year":2008,"finding":"The solution structure of human MCFD2 determined by NMR shows the protein is disordered in the apo (calcium-free) state and folds upon binding Ca2+ to its two C-terminal EF-hand motifs. Disease-causing missense mutants are predominantly disordered even in the presence of calcium, explaining the calcium-dependence of the MCFD2-ERGIC-53 interaction.","method":"Solution NMR structure determination, circular dichroism of mutant variants","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — NMR structure with functional validation by CD spectroscopy, disease mutants characterized, multiple orthogonal methods","pmids":["18590741"],"is_preprint":false},{"year":2009,"finding":"The C-terminal EF-hand domains of MCFD2 are both necessary and sufficient for interaction with LMAN1; the N-terminal non-EF-hand region is dispensable for LMAN1 binding. The EF-hand domains also mediate interaction with FV and FVIII, but through separate binding sites: mutations abolishing LMAN1 binding (and disrupting tertiary structure) still retain FV/FVIII binding, indicating FV/FVIII interaction is independent of Ca2+-induced folding.","method":"Deletion mutagenesis, co-immunoprecipitation, circular dichroism spectroscopy","journal":"Blood","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — domain mapping by deletion/mutagenesis combined with CD spectroscopy and Co-IP, multiple orthogonal methods in one study","pmids":["20007547"],"is_preprint":false},{"year":2010,"finding":"Crystal structure of the LMAN1-CRD/MCFD2 complex reveals that LMAN1 interacts with MCFD2 through its N-terminal β-sheet of the CRD; mutations in the first β-sheet abolish MCFD2 binding without affecting mannose binding. Mutations in the Ca2+- and sugar-binding sites of the CRD disrupt FV/FVIII interaction without affecting MCFD2 binding, demonstrating distinct, separable binding sites for MCFD2 and cargo (FV/FVIII) on LMAN1. Monomeric LMAN1 mutants are defective in ER exit and unable to interact with MCFD2, showing oligomerization is required for cargo receptor function.","method":"Crystal structure, site-directed mutagenesis, co-immunoprecipitation","journal":"Blood / FEBS letters","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure combined with mutagenesis and Co-IP, independently reported in two papers (PMID 20817851 and 20138881)","pmids":["20817851","20138881"],"is_preprint":false},{"year":2011,"finding":"MCFD2-deficient mice have lower plasma FV and FVIII levels than LMAN1-deficient mice. Doubly deficient (LMAN1/MCFD2) mice show FV/FVIII levels matching LMAN1-deficient mice, suggesting an alternative secretion pathway exists. Both LMAN1 and MCFD2 are required for efficient ER exit of α1-antitrypsin (AAT), as demonstrated by reduced plasma AAT and accumulation in hepatocyte ER in singly and doubly deficient mice.","method":"Gene targeting (knockout mice), plasma protein level measurement, hepatocyte ER fractionation","journal":"Blood advances","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic KO mouse models with multiple protein readouts, double-KO epistasis, replicated across genetic backgrounds","pmids":["29735583"],"is_preprint":false},{"year":2020,"finding":"Crystallographic snapshots of ERGIC-53-CRD/MCFD2 complexes reveal that MCFD2 exhibits significant conformational plasticity whereas ERGIC-53-CRD does not, suggesting that MCFD2's structural flexibility is relevant to its ability to accommodate various polypeptide cargo ligands.","method":"X-ray crystallography (multiple crystal forms, 1.60 Å resolution)","journal":"Acta crystallographica. Section F, Structural biology communications","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — high-resolution crystal structures, but functional inference from structural comparison only, single lab","pmids":["32356523"],"is_preprint":false},{"year":2022,"finding":"LMAN1 and MCFD2 function as a cargo receptor complex for ER-to-Golgi transport of α1-antitrypsin (AAT). LMAN1 or MCFD2 KO cells show reduced AAT secretion and elevated intracellular AAT due to delayed ER-to-Golgi transport. AAT interaction with LMAN1 is independent of MCFD2 (by Co-IP in MCFD2 KO cells). Elimination of the second N-glycosylation site of AAT abolished LMAN1-dependent secretion, indicating lectin-glycan interaction is critical. Secretion of AAT Z-variant (monomers and polymers) is also LMAN1-dependent.","method":"CRISPR/KO cell lines, Co-immunoprecipitation, secretion/chase assays, glycosylation mutant analysis","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO cells with rescue experiments, Co-IP, glycosylation mutants, multiple orthogonal methods, functional readout","pmids":["35822856"],"is_preprint":false},{"year":2023,"finding":"Overexpression of either wild-type or mutant MCFD2 alone is sufficient to rescue FV/FVIII secretion defects in LMAN1-deficient cells, suggesting that MCFD2 carries out cargo binding and transport while LMAN1 primarily serves as a shuttling carrier for MCFD2. N-glycan binding by LMAN1 is not essential for FV/FVIII transport, as LMAN1 mutants abolishing carbohydrate binding can still partially rescue secretion.","method":"LMAN1/MCFD2-deficient cell lines, overexpression rescue assays, functional secretion assays","journal":"Blood advances","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — defined KO cell lines with rescue assays, single lab, multiple cell types tested","pmids":["36490287"],"is_preprint":false}],"current_model":"MCFD2 is a soluble EF-hand protein that forms a calcium-dependent 1:1 complex with the transmembrane lectin LMAN1 (ERGIC-53) in the early secretory pathway, where MCFD2 uses its C-terminal EF-hand domains (which fold upon Ca2+ binding) to bind both LMAN1 and cargo proteins (FV, FVIII, and AAT) through distinct binding sites, functioning as the cargo-recognition subunit of the LMAN1-MCFD2 receptor complex that cycles between the ER and ERGIC to mediate efficient ER-to-Golgi transport of these secretory proteins."},"narrative":{"mechanistic_narrative":"MCFD2 is a soluble, calcium-binding cargo-recognition subunit of the early secretory pathway that pairs with the transmembrane lectin LMAN1 (ERGIC-53) to mediate efficient ER-to-Golgi transport of selected secretory glycoproteins, most notably coagulation factors V and VIII [PMID:15886209, PMID:17010120]. MCFD2 and LMAN1 form a 1:1, calcium-dependent complex; MCFD2 is retained in the ER through this interaction and is secreted when LMAN1 is absent [PMID:15886209, PMID:17010120]. Structurally, MCFD2 is intrinsically disordered in the apo state and folds upon binding Ca2+ to its two C-terminal EF-hand motifs, which are necessary and sufficient for LMAN1 binding, while the N-terminal region is dispensable [PMID:18590741, PMID:20007547]. The EF-hand region also engages cargo (FV/FVIII) through binding sites separable from the LMAN1 interface, such that mutations disrupting Ca2+-induced folding and LMAN1 binding still retain cargo binding [PMID:20007547]. On the receptor side, LMAN1 contacts MCFD2 via the N-terminal β-sheet of its carbohydrate-recognition domain, distinct from its Ca2+/sugar-binding cargo and mannose sites, and must oligomerize to function as a cargo receptor [PMID:20817851, PMID:20138881]. The complex acts with cargo selectivity—required for FV/FVIII but dispensable for cathepsin binding—and also promotes ER exit of α1-antitrypsin, where LMAN1's lectin-glycan interaction is critical [PMID:17010120, PMID:29735583, PMID:35822856]. Within the complex MCFD2 carries out cargo binding and transport while LMAN1 primarily serves as a shuttling carrier, and disease-causing MCFD2 missense mutations (e.g., I136T) reduce complex affinity by orders of magnitude and cause combined factor V and factor VIII deficiency [PMID:16304051, PMID:18056485, PMID:36490287].","teleology":[{"year":2005,"claim":"Established that MCFD2 physically partners with LMAN1 in a defined stoichiometry and directly contacts coagulation factor VIII, defining the molecular basis of the cargo receptor complex.","evidence":"Cross-linking immunoprecipitation, reciprocal Co-IP, and stoichiometry analysis in the early secretory pathway","pmids":["15886209"],"confidence":"High","gaps":["Did not resolve which structural elements of MCFD2 mediate each interaction","Cargo binding site on MCFD2 versus LMAN1 not yet distinguished"]},{"year":2005,"claim":"Showed that disease-associated MCFD2 mutations need not fully abolish complex formation to cause clinically significant FV/FVIII deficiency, refining the genotype-phenotype relationship.","evidence":"Co-IP and Western blot of patient-derived lymphoblasts carrying the I136T mutation","pmids":["16304051"],"confidence":"Medium","gaps":["Quantitative threshold of residual complex for secretion not defined","Single patient mutation, single lab"]},{"year":2006,"claim":"Defined cargo selectivity by demonstrating MCFD2 is specifically required for FV/FVIII but dispensable for other ERGIC-53 glycoprotein cargo, and that ERGIC-53 retains MCFD2 in the ER.","evidence":"siRNA knockdown and YFP fragment complementation assay for in vivo cargo binding","pmids":["17010120"],"confidence":"High","gaps":["Molecular determinants of cargo selectivity unresolved","Did not address non-coagulation cargo such as AAT"]},{"year":2007,"claim":"Identified the C-terminus and calcium dependence as structural prerequisites for the MCFD2–ERGIC-53 interaction and quantified the affinity loss in disease mutants.","evidence":"Biochemical binding assays, C-terminal deletion analysis, surface plasmon resonance, and flow cytometry; calcium-dependence below 0.2 mM measured","pmids":["17971482","18056485"],"confidence":"High","gaps":["Structural basis of disorder-to-order transition not yet visualized","How MCFD2 enhances ERGIC-53 sugar binding mechanistically unclear"]},{"year":2008,"claim":"Explained the calcium dependence at atomic resolution: MCFD2 is disordered without Ca2+ and folds upon binding to its EF-hands, while disease mutants fail to fold even with calcium.","evidence":"Solution NMR structure determination with circular dichroism of mutant variants","pmids":["18590741"],"confidence":"High","gaps":["Structure of the bound complex with LMAN1 not yet determined","Cargo-bound conformation not resolved"]},{"year":2009,"claim":"Mapped the binding architecture, showing the C-terminal EF-hands are necessary and sufficient for LMAN1 binding and that cargo binding occurs through separate sites independent of Ca2+-induced folding.","evidence":"Deletion mutagenesis, Co-IP, and CD spectroscopy","pmids":["20007547"],"confidence":"High","gaps":["Precise cargo-contacting residues on MCFD2 not identified","How a partially folded mutant retains cargo binding mechanistically unclear"]},{"year":2010,"claim":"Defined the receptor side structurally: LMAN1 binds MCFD2 via its CRD β-sheet, separate from its sugar/cargo sites, and requires oligomerization for cargo receptor function.","evidence":"Crystal structure of LMAN1-CRD/MCFD2 complex with site-directed mutagenesis and Co-IP","pmids":["20817851","20138881"],"confidence":"High","gaps":["Full-length complex with cargo bound not crystallized","Stoichiometry of cargo loading per oligomer unknown"]},{"year":2011,"claim":"Genetic dissection in mice revealed non-identical roles of LMAN1 and MCFD2 and extended the receptor's cargo repertoire to α1-antitrypsin.","evidence":"LMAN1 and MCFD2 single and double knockout mice with plasma protein measurements and hepatocyte ER fractionation","pmids":["29735583"],"confidence":"High","gaps":["Identity of the alternative FV/FVIII secretion pathway not determined","Mechanism distinguishing single- versus double-KO phenotypes unclear"]},{"year":2020,"claim":"Showed MCFD2 possesses conformational plasticity that LMAN1-CRD lacks, providing a structural rationale for accommodating diverse polypeptide cargo.","evidence":"High-resolution X-ray crystallography of multiple ERGIC-53-CRD/MCFD2 crystal forms","pmids":["32356523"],"confidence":"Medium","gaps":["Functional role of plasticity inferred from structure only","No cargo-bound structure to confirm accommodation"]},{"year":2022,"claim":"Established the LMAN1-MCFD2 complex as a lectin-dependent cargo receptor for α1-antitrypsin, with LMAN1 binding AAT independently of MCFD2 via glycan recognition.","evidence":"CRISPR knockout cell lines, Co-IP, secretion/chase assays, and AAT glycosylation mutants including the Z variant","pmids":["35822856"],"confidence":"High","gaps":["Why AAT depends on glycan binding while FV/FVIII can bypass it not reconciled","Quantitative contribution of MCFD2 to AAT transport not isolated"]},{"year":2023,"claim":"Reassigned functional division of labor: MCFD2 alone can drive FV/FVIII cargo binding and transport, with LMAN1 acting mainly as a shuttling carrier and its lectin activity dispensable for these cargoes.","evidence":"Overexpression rescue assays in LMAN1/MCFD2-deficient cell lines with functional secretion readouts","pmids":["36490287"],"confidence":"Medium","gaps":["Apparent contradiction with glycan-dependent AAT transport unresolved","Single lab; mechanism of MCFD2-driven shuttling without LMAN1 lectin function unclear"]},{"year":null,"claim":"The identity of the alternative, LMAN1/MCFD2-independent secretion pathway for FV/FVIII and the structural basis for cargo loading onto the assembled receptor remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No cargo-bound structure of the full complex","Alternative secretion route uncharacterized","Reconciliation of glycan-dependent versus glycan-independent cargo transport pending"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0038024","term_label":"cargo receptor activity","supporting_discovery_ids":[0,2,6,10]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[6,7,11]}],"localization":[{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[0,2,8]},{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[8,10]}],"pathway":[{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[2,8,10]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[2,10,11]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[0,8]}],"complexes":["LMAN1-MCFD2 cargo receptor complex"],"partners":["LMAN1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8NI22","full_name":"Multiple coagulation factor deficiency protein 2","aliases":["Neural stem cell-derived neuronal survival protein"],"length_aa":146,"mass_kda":16.4,"function":"The MCFD2-LMAN1 complex forms a specific cargo receptor for the ER-to-Golgi transport of selected proteins. Plays a role in the secretion of coagulation factors","subcellular_location":"Endoplasmic reticulum-Golgi intermediate compartment; Endoplasmic reticulum; Golgi apparatus","url":"https://www.uniprot.org/uniprotkb/Q8NI22/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MCFD2","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"LMAN1","stoichiometry":10.0},{"gene":"COPA","stoichiometry":0.2},{"gene":"COPE","stoichiometry":0.2},{"gene":"SEC13","stoichiometry":0.2},{"gene":"YIPF5","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/MCFD2","total_profiled":1310},"omim":[{"mim_id":"613625","title":"FACTOR V AND FACTOR VIII, COMBINED DEFICIENCY OF, 2; F5F8D2","url":"https://www.omim.org/entry/613625"},{"mim_id":"607788","title":"MULTIPLE COAGULATION FACTOR DEFICIENCY PROTEIN 2; MCFD2","url":"https://www.omim.org/entry/607788"},{"mim_id":"601567","title":"LECTIN, MANNOSE-BINDING 1; LMAN1","url":"https://www.omim.org/entry/601567"},{"mim_id":"227300","title":"FACTOR V AND FACTOR VIII, COMBINED DEFICIENCY OF, 1; F5F8D1","url":"https://www.omim.org/entry/227300"},{"mim_id":"134510","title":"FACTOR VIII AND FACTOR IX, COMBINED DEFICIENCY OF; F8F9D","url":"https://www.omim.org/entry/134510"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/MCFD2"},"hgnc":{"alias_symbol":["F5F8D","LMAN1IP","SDNSF"],"prev_symbol":[]},"alphafold":{"accession":"Q8NI22","domains":[{"cath_id":"1.10.238.10","chopping":"68-144","consensus_level":"high","plddt":89.95,"start":68,"end":144}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8NI22","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8NI22-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8NI22-F1-predicted_aligned_error_v6.png","plddt_mean":76.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MCFD2","jax_strain_url":"https://www.jax.org/strain/search?query=MCFD2"},"sequence":{"accession":"Q8NI22","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8NI22.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8NI22/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8NI22"}},"corpus_meta":[{"pmid":"15886209","id":"PMC_15886209","title":"LMAN1 and MCFD2 form a cargo receptor complex and interact with coagulation factor VIII in the early secretory pathway.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/15886209","citation_count":114,"is_preprint":false},{"pmid":"16304051","id":"PMC_16304051","title":"Combined deficiency of factor V and factor VIII is due to mutations in either LMAN1 or MCFD2.","date":"2005","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/16304051","citation_count":88,"is_preprint":false},{"pmid":"17010120","id":"PMC_17010120","title":"Cargo selectivity of the ERGIC-53/MCFD2 transport receptor complex.","date":"2006","source":"Traffic (Copenhagen, Denmark)","url":"https://pubmed.ncbi.nlm.nih.gov/17010120","citation_count":66,"is_preprint":false},{"pmid":"20817851","id":"PMC_20817851","title":"Molecular basis of LMAN1 in coordinating LMAN1-MCFD2 cargo receptor formation and ER-to-Golgi transport of FV/FVIII.","date":"2010","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/20817851","citation_count":50,"is_preprint":false},{"pmid":"18056485","id":"PMC_18056485","title":"The sugar-binding ability of ERGIC-53 is enhanced by its interaction with MCFD2.","date":"2007","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/18056485","citation_count":46,"is_preprint":false},{"pmid":"18590741","id":"PMC_18590741","title":"New insights into multiple coagulation factor deficiency from the solution structure of human MCFD2.","date":"2008","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/18590741","citation_count":31,"is_preprint":false},{"pmid":"20007547","id":"PMC_20007547","title":"EF-hand domains of MCFD2 mediate interactions with both LMAN1 and coagulation factor V or VIII.","date":"2009","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/20007547","citation_count":23,"is_preprint":false},{"pmid":"20138881","id":"PMC_20138881","title":"Crystal structure of the LMAN1-CRD/MCFD2 transport receptor complex provides insight into combined deficiency of factor V and factor VIII.","date":"2010","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/20138881","citation_count":22,"is_preprint":false},{"pmid":"17971482","id":"PMC_17971482","title":"Deletion of 3 residues from the C-terminus of MCFD2 affects binding to ERGIC-53 and causes combined factor V and factor VIII deficiency.","date":"2007","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/17971482","citation_count":20,"is_preprint":false},{"pmid":"16044454","id":"PMC_16044454","title":"Mutations in the MCFD2 gene and a novel mutation in the LMAN1 gene in Indian families with combined deficiency of factor V and VIII.","date":"2005","source":"American journal of hematology","url":"https://pubmed.ncbi.nlm.nih.gov/16044454","citation_count":20,"is_preprint":false},{"pmid":"29735583","id":"PMC_29735583","title":"Analysis of MCFD2- and LMAN1-deficient mice demonstrates distinct functions in vivo.","date":"2018","source":"Blood advances","url":"https://pubmed.ncbi.nlm.nih.gov/29735583","citation_count":19,"is_preprint":false},{"pmid":"35322856","id":"PMC_35322856","title":"LMAN1-MCFD2 complex is a cargo receptor for the ER-Golgi transport of α1-antitrypsin.","date":"2022","source":"The Biochemical journal","url":"https://pubmed.ncbi.nlm.nih.gov/35322856","citation_count":16,"is_preprint":false},{"pmid":"17610559","id":"PMC_17610559","title":"Mutations in the MCFD2 gene are predominant among patients with hereditary combined FV and FVIII deficiency (F5F8D) in India.","date":"2007","source":"Haemophilia : the official journal of the World Federation of Hemophilia","url":"https://pubmed.ncbi.nlm.nih.gov/17610559","citation_count":14,"is_preprint":false},{"pmid":"21492322","id":"PMC_21492322","title":"Analysis of newly detected mutations in the MCFD2 gene giving rise to combined deficiency of coagulation factors V and VIII.","date":"2011","source":"Haemophilia : the official journal of the World Federation of Hemophilia","url":"https://pubmed.ncbi.nlm.nih.gov/21492322","citation_count":12,"is_preprint":false},{"pmid":"36490287","id":"PMC_36490287","title":"Separate roles of LMAN1 and MCFD2 in ER-to-Golgi trafficking of FV and FVIII.","date":"2023","source":"Blood advances","url":"https://pubmed.ncbi.nlm.nih.gov/36490287","citation_count":10,"is_preprint":false},{"pmid":"32356523","id":"PMC_32356523","title":"Crystallographic snapshots of the EF-hand protein MCFD2 complexed with the intracellular lectin ERGIC-53 involved in glycoprotein transport.","date":"2020","source":"Acta crystallographica. Section F, Structural biology communications","url":"https://pubmed.ncbi.nlm.nih.gov/32356523","citation_count":8,"is_preprint":false},{"pmid":"35963666","id":"PMC_35963666","title":"Effect of co-overexpression of the cargo receptor ERGIC-53/MCFD2 on antibody production and intracellular IgG secretion in recombinant Chinese hamster ovary cells.","date":"2022","source":"Journal of bioscience and bioengineering","url":"https://pubmed.ncbi.nlm.nih.gov/35963666","citation_count":8,"is_preprint":false},{"pmid":"18685427","id":"PMC_18685427","title":"The first case of combined coagulation factor V and coagulation factor VIII deficiency in Poland due to a novel p.Tyr135Asn missense mutation in the MCFD2 gene.","date":"2008","source":"Blood coagulation & fibrinolysis : an international journal in haemostasis and thrombosis","url":"https://pubmed.ncbi.nlm.nih.gov/18685427","citation_count":8,"is_preprint":false},{"pmid":"22208273","id":"PMC_22208273","title":"Unveiling the unfolding pathway of F5F8D disorder-associated D81H/V100D mutant of MCFD2 via multiple molecular dynamics simulations.","date":"2012","source":"Journal of biomolecular structure & dynamics","url":"https://pubmed.ncbi.nlm.nih.gov/22208273","citation_count":5,"is_preprint":false},{"pmid":"39222205","id":"PMC_39222205","title":"RNAi targeting LMAN1-MCFD2 complex promotes anticoagulation in mice.","date":"2024","source":"Journal of thrombosis and thrombolysis","url":"https://pubmed.ncbi.nlm.nih.gov/39222205","citation_count":1,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":11757,"output_tokens":3081,"usd":0.040743,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10555,"output_tokens":3739,"usd":0.073125,"stage2_stop_reason":"end_turn"},"total_usd":0.113868,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2005,\n      \"finding\": \"LMAN1 and MCFD2 form a 1:1 stoichiometric complex in the early secretory pathway, and both proteins interact with coagulation factor VIII (at the B domain) via calcium-dependent protein-protein interactions, independent of factor VIII glycosylation state. MCFD2 is retained in the ER through its interaction with LMAN1, and MCFD2 interaction with FVIII is independent of LMAN1-MCFD2 complex formation.\",\n      \"method\": \"Cross-linking immunoprecipitation, co-immunoprecipitation, Western blot, stoichiometry analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP with cross-linking, multiple orthogonal methods, foundational study replicated by subsequent work\",\n      \"pmids\": [\"15886209\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Missense mutations in MCFD2 (e.g., I136T) result in a low but detectable level of residual LMAN1-MCFD2 complex, suggesting complete loss of the complex is not required for clinically significant reduction in FV and FVIII secretion.\",\n      \"method\": \"Immunoprecipitation and Western blot of patient-derived lymphoblasts\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — patient-derived cells, Co-IP and Western blot, single lab\",\n      \"pmids\": [\"16304051\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"MCFD2 is dispensable for binding of cathepsin Z and cathepsin C to ERGIC-53, demonstrating cargo selectivity: MCFD2 is specifically required for recruitment of coagulation factors V and VIII but not for glycoprotein cargo in general. In the absence of ERGIC-53, MCFD2 is secreted rather than retained.\",\n      \"method\": \"siRNA knockdown, yellow fluorescent protein fragment complementation assay (in vivo cargo binding)\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — siRNA knockdown combined with YFP-fragment complementation, two orthogonal methods establishing cargo selectivity\",\n      \"pmids\": [\"17010120\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Deletion of the C-terminal 3 residues (ΔS-L-Q) of MCFD2 impairs binding to ERGIC-53 due to modification of the 3D structure of MCFD2, establishing that the C-terminus is structurally critical for the ERGIC-53/MCFD2 interaction.\",\n      \"method\": \"Biochemical binding assay, structural analysis of mutant MCFD2\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — patient mutation, biochemical and structural analysis, single lab\",\n      \"pmids\": [\"17971482\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"MCFD2 interaction with ERGIC-53 enhances the sugar-binding ability of ERGIC-53 (specifically for high-mannose oligosaccharides, especially M8B). F5F8D patient MCFD2 missense mutants show 3–4 orders of magnitude lower affinity for ERGIC-53 by surface plasmon resonance. The MCFD2-ERGIC-53 interaction is calcium-dependent, becoming significantly weaker below 0.2 mM calcium.\",\n      \"method\": \"Flow cytometry binding assay, surface plasmon resonance, endo H treatment\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro SPR binding assay combined with cell-based flow cytometry, multiple orthogonal methods, calcium-dependence quantified\",\n      \"pmids\": [\"18056485\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"The solution structure of human MCFD2 determined by NMR shows the protein is disordered in the apo (calcium-free) state and folds upon binding Ca2+ to its two C-terminal EF-hand motifs. Disease-causing missense mutants are predominantly disordered even in the presence of calcium, explaining the calcium-dependence of the MCFD2-ERGIC-53 interaction.\",\n      \"method\": \"Solution NMR structure determination, circular dichroism of mutant variants\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — NMR structure with functional validation by CD spectroscopy, disease mutants characterized, multiple orthogonal methods\",\n      \"pmids\": [\"18590741\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"The C-terminal EF-hand domains of MCFD2 are both necessary and sufficient for interaction with LMAN1; the N-terminal non-EF-hand region is dispensable for LMAN1 binding. The EF-hand domains also mediate interaction with FV and FVIII, but through separate binding sites: mutations abolishing LMAN1 binding (and disrupting tertiary structure) still retain FV/FVIII binding, indicating FV/FVIII interaction is independent of Ca2+-induced folding.\",\n      \"method\": \"Deletion mutagenesis, co-immunoprecipitation, circular dichroism spectroscopy\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — domain mapping by deletion/mutagenesis combined with CD spectroscopy and Co-IP, multiple orthogonal methods in one study\",\n      \"pmids\": [\"20007547\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Crystal structure of the LMAN1-CRD/MCFD2 complex reveals that LMAN1 interacts with MCFD2 through its N-terminal β-sheet of the CRD; mutations in the first β-sheet abolish MCFD2 binding without affecting mannose binding. Mutations in the Ca2+- and sugar-binding sites of the CRD disrupt FV/FVIII interaction without affecting MCFD2 binding, demonstrating distinct, separable binding sites for MCFD2 and cargo (FV/FVIII) on LMAN1. Monomeric LMAN1 mutants are defective in ER exit and unable to interact with MCFD2, showing oligomerization is required for cargo receptor function.\",\n      \"method\": \"Crystal structure, site-directed mutagenesis, co-immunoprecipitation\",\n      \"journal\": \"Blood / FEBS letters\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure combined with mutagenesis and Co-IP, independently reported in two papers (PMID 20817851 and 20138881)\",\n      \"pmids\": [\"20817851\", \"20138881\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"MCFD2-deficient mice have lower plasma FV and FVIII levels than LMAN1-deficient mice. Doubly deficient (LMAN1/MCFD2) mice show FV/FVIII levels matching LMAN1-deficient mice, suggesting an alternative secretion pathway exists. Both LMAN1 and MCFD2 are required for efficient ER exit of α1-antitrypsin (AAT), as demonstrated by reduced plasma AAT and accumulation in hepatocyte ER in singly and doubly deficient mice.\",\n      \"method\": \"Gene targeting (knockout mice), plasma protein level measurement, hepatocyte ER fractionation\",\n      \"journal\": \"Blood advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic KO mouse models with multiple protein readouts, double-KO epistasis, replicated across genetic backgrounds\",\n      \"pmids\": [\"29735583\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Crystallographic snapshots of ERGIC-53-CRD/MCFD2 complexes reveal that MCFD2 exhibits significant conformational plasticity whereas ERGIC-53-CRD does not, suggesting that MCFD2's structural flexibility is relevant to its ability to accommodate various polypeptide cargo ligands.\",\n      \"method\": \"X-ray crystallography (multiple crystal forms, 1.60 Å resolution)\",\n      \"journal\": \"Acta crystallographica. Section F, Structural biology communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — high-resolution crystal structures, but functional inference from structural comparison only, single lab\",\n      \"pmids\": [\"32356523\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"LMAN1 and MCFD2 function as a cargo receptor complex for ER-to-Golgi transport of α1-antitrypsin (AAT). LMAN1 or MCFD2 KO cells show reduced AAT secretion and elevated intracellular AAT due to delayed ER-to-Golgi transport. AAT interaction with LMAN1 is independent of MCFD2 (by Co-IP in MCFD2 KO cells). Elimination of the second N-glycosylation site of AAT abolished LMAN1-dependent secretion, indicating lectin-glycan interaction is critical. Secretion of AAT Z-variant (monomers and polymers) is also LMAN1-dependent.\",\n      \"method\": \"CRISPR/KO cell lines, Co-immunoprecipitation, secretion/chase assays, glycosylation mutant analysis\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO cells with rescue experiments, Co-IP, glycosylation mutants, multiple orthogonal methods, functional readout\",\n      \"pmids\": [\"35822856\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Overexpression of either wild-type or mutant MCFD2 alone is sufficient to rescue FV/FVIII secretion defects in LMAN1-deficient cells, suggesting that MCFD2 carries out cargo binding and transport while LMAN1 primarily serves as a shuttling carrier for MCFD2. N-glycan binding by LMAN1 is not essential for FV/FVIII transport, as LMAN1 mutants abolishing carbohydrate binding can still partially rescue secretion.\",\n      \"method\": \"LMAN1/MCFD2-deficient cell lines, overexpression rescue assays, functional secretion assays\",\n      \"journal\": \"Blood advances\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — defined KO cell lines with rescue assays, single lab, multiple cell types tested\",\n      \"pmids\": [\"36490287\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MCFD2 is a soluble EF-hand protein that forms a calcium-dependent 1:1 complex with the transmembrane lectin LMAN1 (ERGIC-53) in the early secretory pathway, where MCFD2 uses its C-terminal EF-hand domains (which fold upon Ca2+ binding) to bind both LMAN1 and cargo proteins (FV, FVIII, and AAT) through distinct binding sites, functioning as the cargo-recognition subunit of the LMAN1-MCFD2 receptor complex that cycles between the ER and ERGIC to mediate efficient ER-to-Golgi transport of these secretory proteins.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MCFD2 is a soluble, calcium-binding cargo-recognition subunit of the early secretory pathway that pairs with the transmembrane lectin LMAN1 (ERGIC-53) to mediate efficient ER-to-Golgi transport of selected secretory glycoproteins, most notably coagulation factors V and VIII [#0, #2]. MCFD2 and LMAN1 form a 1:1, calcium-dependent complex; MCFD2 is retained in the ER through this interaction and is secreted when LMAN1 is absent [#0, #2]. Structurally, MCFD2 is intrinsically disordered in the apo state and folds upon binding Ca2+ to its two C-terminal EF-hand motifs, which are necessary and sufficient for LMAN1 binding, while the N-terminal region is dispensable [#5, #6]. The EF-hand region also engages cargo (FV/FVIII) through binding sites separable from the LMAN1 interface, such that mutations disrupting Ca2+-induced folding and LMAN1 binding still retain cargo binding [#6]. On the receptor side, LMAN1 contacts MCFD2 via the N-terminal β-sheet of its carbohydrate-recognition domain, distinct from its Ca2+/sugar-binding cargo and mannose sites, and must oligomerize to function as a cargo receptor [#7]. The complex acts with cargo selectivity—required for FV/FVIII but dispensable for cathepsin binding—and also promotes ER exit of α1-antitrypsin, where LMAN1's lectin-glycan interaction is critical [#2, #8, #10]. Within the complex MCFD2 carries out cargo binding and transport while LMAN1 primarily serves as a shuttling carrier, and disease-causing MCFD2 missense mutations (e.g., I136T) reduce complex affinity by orders of magnitude and cause combined factor V and factor VIII deficiency [#1, #4, #11].\",\n  \"teleology\": [\n    {\n      \"year\": 2005,\n      \"claim\": \"Established that MCFD2 physically partners with LMAN1 in a defined stoichiometry and directly contacts coagulation factor VIII, defining the molecular basis of the cargo receptor complex.\",\n      \"evidence\": \"Cross-linking immunoprecipitation, reciprocal Co-IP, and stoichiometry analysis in the early secretory pathway\",\n      \"pmids\": [\"15886209\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve which structural elements of MCFD2 mediate each interaction\", \"Cargo binding site on MCFD2 versus LMAN1 not yet distinguished\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Showed that disease-associated MCFD2 mutations need not fully abolish complex formation to cause clinically significant FV/FVIII deficiency, refining the genotype-phenotype relationship.\",\n      \"evidence\": \"Co-IP and Western blot of patient-derived lymphoblasts carrying the I136T mutation\",\n      \"pmids\": [\"16304051\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Quantitative threshold of residual complex for secretion not defined\", \"Single patient mutation, single lab\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Defined cargo selectivity by demonstrating MCFD2 is specifically required for FV/FVIII but dispensable for other ERGIC-53 glycoprotein cargo, and that ERGIC-53 retains MCFD2 in the ER.\",\n      \"evidence\": \"siRNA knockdown and YFP fragment complementation assay for in vivo cargo binding\",\n      \"pmids\": [\"17010120\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular determinants of cargo selectivity unresolved\", \"Did not address non-coagulation cargo such as AAT\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Identified the C-terminus and calcium dependence as structural prerequisites for the MCFD2–ERGIC-53 interaction and quantified the affinity loss in disease mutants.\",\n      \"evidence\": \"Biochemical binding assays, C-terminal deletion analysis, surface plasmon resonance, and flow cytometry; calcium-dependence below 0.2 mM measured\",\n      \"pmids\": [\"17971482\", \"18056485\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of disorder-to-order transition not yet visualized\", \"How MCFD2 enhances ERGIC-53 sugar binding mechanistically unclear\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Explained the calcium dependence at atomic resolution: MCFD2 is disordered without Ca2+ and folds upon binding to its EF-hands, while disease mutants fail to fold even with calcium.\",\n      \"evidence\": \"Solution NMR structure determination with circular dichroism of mutant variants\",\n      \"pmids\": [\"18590741\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structure of the bound complex with LMAN1 not yet determined\", \"Cargo-bound conformation not resolved\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Mapped the binding architecture, showing the C-terminal EF-hands are necessary and sufficient for LMAN1 binding and that cargo binding occurs through separate sites independent of Ca2+-induced folding.\",\n      \"evidence\": \"Deletion mutagenesis, Co-IP, and CD spectroscopy\",\n      \"pmids\": [\"20007547\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Precise cargo-contacting residues on MCFD2 not identified\", \"How a partially folded mutant retains cargo binding mechanistically unclear\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Defined the receptor side structurally: LMAN1 binds MCFD2 via its CRD β-sheet, separate from its sugar/cargo sites, and requires oligomerization for cargo receptor function.\",\n      \"evidence\": \"Crystal structure of LMAN1-CRD/MCFD2 complex with site-directed mutagenesis and Co-IP\",\n      \"pmids\": [\"20817851\", \"20138881\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full-length complex with cargo bound not crystallized\", \"Stoichiometry of cargo loading per oligomer unknown\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Genetic dissection in mice revealed non-identical roles of LMAN1 and MCFD2 and extended the receptor's cargo repertoire to α1-antitrypsin.\",\n      \"evidence\": \"LMAN1 and MCFD2 single and double knockout mice with plasma protein measurements and hepatocyte ER fractionation\",\n      \"pmids\": [\"29735583\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the alternative FV/FVIII secretion pathway not determined\", \"Mechanism distinguishing single- versus double-KO phenotypes unclear\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Showed MCFD2 possesses conformational plasticity that LMAN1-CRD lacks, providing a structural rationale for accommodating diverse polypeptide cargo.\",\n      \"evidence\": \"High-resolution X-ray crystallography of multiple ERGIC-53-CRD/MCFD2 crystal forms\",\n      \"pmids\": [\"32356523\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional role of plasticity inferred from structure only\", \"No cargo-bound structure to confirm accommodation\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Established the LMAN1-MCFD2 complex as a lectin-dependent cargo receptor for α1-antitrypsin, with LMAN1 binding AAT independently of MCFD2 via glycan recognition.\",\n      \"evidence\": \"CRISPR knockout cell lines, Co-IP, secretion/chase assays, and AAT glycosylation mutants including the Z variant\",\n      \"pmids\": [\"35822856\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Why AAT depends on glycan binding while FV/FVIII can bypass it not reconciled\", \"Quantitative contribution of MCFD2 to AAT transport not isolated\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Reassigned functional division of labor: MCFD2 alone can drive FV/FVIII cargo binding and transport, with LMAN1 acting mainly as a shuttling carrier and its lectin activity dispensable for these cargoes.\",\n      \"evidence\": \"Overexpression rescue assays in LMAN1/MCFD2-deficient cell lines with functional secretion readouts\",\n      \"pmids\": [\"36490287\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Apparent contradiction with glycan-dependent AAT transport unresolved\", \"Single lab; mechanism of MCFD2-driven shuttling without LMAN1 lectin function unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The identity of the alternative, LMAN1/MCFD2-independent secretion pathway for FV/FVIII and the structural basis for cargo loading onto the assembled receptor remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No cargo-bound structure of the full complex\", \"Alternative secretion route uncharacterized\", \"Reconciliation of glycan-dependent versus glycan-independent cargo transport pending\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0038024\", \"supporting_discovery_ids\": [0, 2, 6, 10]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [6, 7, 11]},\n      {\"term_id\": \"GO:0005509\", \"supporting_discovery_ids\": [4, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [0, 2, 8]},\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [8, 10]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [2, 8, 10]},\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [2, 10, 11]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0, 8]}\n    ],\n    \"complexes\": [\"LMAN1-MCFD2 cargo receptor complex\"],\n    \"partners\": [\"LMAN1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":{"gene":"MCFD2","tier":"GROUNDING","verdict":"Evidence-grounding concern","subtype":"fabrication","uniprot_band":"sparse","rules_fired":"R7","issue":"R7: fabricated (no corpus paper): 35822856"},"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}