{"gene":"MASP2","run_date":"2026-06-10T02:59:50","timeline":{"discoveries":[{"year":2002,"finding":"MASP-2 and MAp19 are alternative splice products of a single MASP2 gene; MASP-2 is the serine protease responsible for cleaving C4 and C2 to generate the C3 convertase C4bC2b in the lectin pathway, while MAp19 consists only of the first two domains of MASP-2 plus four additional residues and lacks a catalytic domain.","method":"Molecular cloning, gene structure analysis, and functional reconstitution assays","journal":"Immunobiology","confidence":"High","confidence_rationale":"Tier 1 / Strong — established by multiple labs using molecular cloning, gene structure determination, and functional complement activation assays; replicated across multiple independent studies","pmids":["12396007","11426320","9777418","10586086"],"is_preprint":false},{"year":2004,"finding":"The crystal structure of the MASP-2 catalytic fragment (CCP2 + serine protease domain) was solved at 2.25 Å resolution. The CCP2 module stabilizes the SP domain structure. The asymmetric unit contains two molecules with different CCP-SP domain orientations, reflecting modular flexibility at the CCP2/SP joint. Despite nearly identical substrate specificities to C1s, MASP-2 achieves this through a different set of enzyme-substrate interactions, with surface loops (including S1 pocket loops) more similar to trypsin than C1s.","method":"X-ray crystallography at 2.25 Å resolution; differential scanning calorimetry","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — high-resolution crystal structure with functional validation by calorimetry; single rigorous paper with multiple orthogonal methods","pmids":["15364579"],"is_preprint":false},{"year":2004,"finding":"MASP-1 cleaves fluorescent amide substrates (particularly Phe-Gly-Arg-AMC) rapidly, while recombinant MASP-2 barely cleaves any of 14 small fluorescent substrates tested. MASP-2 activity is best measured via cleavage of its natural protein substrate C4. C1-inhibitor inhibits both MASP-1 and MASP-2, but the protease-serpin complex is unusually unstable at alkaline pH. The thrombin inhibitor boroMpg inhibits MASP-1 but not MASP-2. Antithrombin III with heparin inhibits both MASPs.","method":"Fluorescent amide substrate cleavage assays with recombinant and serum-derived MASPs; inhibitor profiling","journal":"Molecular immunology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct in vitro enzymatic assays with defined substrates and inhibitors, multiple substrate panel, single lab but comprehensive","pmids":["14725788"],"is_preprint":false},{"year":2004,"finding":"The X-ray structure of MAp19 (the MASP2 alternative splice product) was solved at 2.5 Å. MAp19 forms a head-to-tail homodimer stabilized by Ca2+ ions at EGF modules. Point mutagenesis identified six residues (Tyr59, Asp60, Glu83, Asp105, Tyr106, Glu109) at the distal end of the CUB1 module that are critical for Ca2+-dependent interaction with MBL and L-ficolin, mapping a common binding site for these pattern recognition molecules.","method":"X-ray crystallography at 2.5 Å; surface plasmon resonance with point mutants","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus mutagenesis validated by SPR binding assays in a single rigorous study","pmids":["15117939"],"is_preprint":false},{"year":2000,"finding":"In serum, MASP-1, MASP-2, and MAp19 associate exclusively with MBL (not C1q), while C1r and C1s associate exclusively with C1q. Full dissociation of MASPs/MAp19 from MBL requires both high salt and calcium chelation (EDTA). The bulk of MASP-1 and MAp19 in serum exist as large complexes with each other that are not bound to MBL or MASP-2, with over 95% of total MASPs and MAp19 not complexed with MBL.","method":"Gel-permeation chromatography; depletion experiments with C1r-deficient serum; complement activation assays on IgG- and mannan-coated microwells","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal binding characterization with biochemical fractionation and functional complement assays; independently consistent findings","pmids":["10878362"],"is_preprint":false},{"year":2006,"finding":"MASP-1 and MASP-2 cooperate to generate the C3 convertase through the MBL pathway. At high serum concentrations, MASP-2 alone is insufficient; MASP-1 must collaborate with MASP-2 for efficient C3b deposition on mannan-coated surfaces. MASP-3 inhibited this synergistic C3b deposition. C3b deposition required C4 and C2 (not factor B), confirming the lectin pathway mechanism.","method":"C3b deposition assay on mannan-coated surfaces using serum depleted of MASP-1, MASP-2, and MASP-3 with reconstitution experiments","journal":"International immunology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reconstitution of defined complement components with functional C3b deposition readout; functional epistasis established","pmids":["17182967"],"is_preprint":false},{"year":2007,"finding":"MASP-2 cleaves C4 and C2 sequentially to form the C3 convertase. C2 does not bind to native C4 but binds tightly to C4b (generated after C4 cleavage), indicating C4 and C2 do not circulate as preformed complexes. C4b remains bound to MASP-2 after cleavage (KD ~0.6 µM, koff ~0.06 s-1), and this C4b.MASP-2 interaction is proposed to favor covalent attachment of C4b near the activating MBL.MASP complex on bacterial surfaces, thereby facilitating C3 convertase assembly.","method":"Surface plasmon resonance binding assays measuring interactions between MASP-2, C4, C2, and activation fragments; kinetic analysis of C4b2 and C2 cleavage","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct binding kinetics by SPR combined with enzymatic assays defining the ordered assembly mechanism","pmids":["17204478"],"is_preprint":false},{"year":2007,"finding":"Phage display substrate library screening revealed MASP-2 cleavage specificity: P1 position is critical, S2 and S3 subsites (preferring Gly at P2 and Leu/hydrophobic at P3) are the next most important determinants. MASP-2 is up to 1000-fold more catalytically active than C1s on peptide substrates. C1-inhibitor inhibits MASP-2 50-fold faster than it inhibits C1s, establishing MASP-2 as a major physiological target of C1-inhibitor.","method":"Randomised substrate phage display library; peptide substrate cleavage assays; serpin inhibition kinetics","journal":"Molecular immunology","confidence":"High","confidence_rationale":"Tier 1 / Strong — phage display substrate profiling plus quantitative kinetic assays, multiple orthogonal approaches in one study","pmids":["17709141"],"is_preprint":false},{"year":2012,"finding":"Both MASP-1 and MASP-2 are essential (not merely auxiliary) for lectin pathway activation. Monospecific evolved inhibitors selective for either MASP-1 or MASP-2 each completely block lectin pathway activation. MASP-1 transactivates MASP-2 zymogen. The first Michaelis-like complex structures of MASP-1 and MASP-2 with substrate-like inhibitors were solved, including a 1.28 Å MASP-2 structure revealing significant structural plasticity of the protease, suggesting induced fit or conformational selection contributes to its substrate specificity.","method":"Directed evolution of monospecific inhibitors; complement activation assays; X-ray crystallography at 1.28 Å (MASP-2 Michaelis complex)","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — inhibitor engineering with functional pathway assays plus high-resolution crystal structure; multiple orthogonal methods in one study","pmids":["22511776"],"is_preprint":false},{"year":2013,"finding":"Although MASP-1 and MASP-2 do not directly form heterodimers, addition of MBL or ficolins (H-, L-, M-ficolin) enables formation of MASP-1–MASP-2 co-complexes within the same pattern recognition molecule complex. These co-complexes are functionally active in complement activation and are present in serum at varying levels that impact the degree of complement activation. MAp44 can inhibit complement not merely by displacing MASP-2 from MBL/ficolins, but by disrupting MASP-1–MASP-2 co-complexes and impairing transactivation.","method":"Co-immunoprecipitation; functional complement activation assays; serum complex characterization","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP combined with functional complement assays establishing mechanistic role of co-complexes","pmids":["23785123"],"is_preprint":false},{"year":2005,"finding":"The higher C4 cleavage efficiency of MASP-2 compared to C1s arises from the complement control protein (CCP) modules of MASP-2, not from its serine protease domain. Chimeric molecules where MASP-2 CCP1/2 modules replaced those of C1s showed Km values in the nanomolar range for C4 (21–27-fold higher kcat/Km than C1s), while the SP domain swap did not confer this advantage. C2 cleavage efficiency was determined by the SP domain of each enzyme.","method":"Multisite-directed mutagenesis to generate C1s/MASP-2 chimeras; enzymatic characterization of C4 and C2 cleavage; esterolytic activity assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — domain-swap mutagenesis with quantitative kinetic characterization clearly dissecting the structural determinants of substrate specificity","pmids":["16227207"],"is_preprint":false},{"year":2005,"finding":"Mouse ficolin A and its splicing variant (but not ficolin B) form complexes with MASP-2 (and sMAP/MAp19), and these ficolin A/MASP-2 complexes show potent complement-activating capacity. sMAP competed with MASP-2 for binding to ficolin A and inhibited complement activation by the ficolin A/MASP-2 complex, establishing sMAP/MAp19 as a competitive inhibitor of MASP-2-mediated complement activation in this context.","method":"Recombinant protein production; co-immunoprecipitation; complement activation assays with purified components","journal":"Immunogenetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional reconstitution with purified recombinant components establishing competitive inhibition; single lab","pmids":["16328467"],"is_preprint":false},{"year":1999,"finding":"Rat and mouse MASP-2 and MAp19 are encoded by a single structural gene (as in humans), are components of the rat MBL pathway activation complex, and are synthesized exclusively in the liver. MASP-2 cleaves C4 within the MBL/MASP complex.","method":"Molecular cloning; Southern blot; PCR; hepatic biosynthesis demonstrated by tissue-specific expression analysis; functional C4 cleavage assay","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 2 / Strong — replicated gene structure finding across species with functional C4 cleavage assay and tissue localization; independently consistent with human data","pmids":["10586086"],"is_preprint":false},{"year":2001,"finding":"The human MASP2 gene is located on chromosome 1p36.23-31 and encodes both the 76 kDa MASP-2 serine protease and the 19 kDa MAp19 protein via alternative polyadenylation/splicing. Comparison with the C1s gene revealed identical positions of introns separating orthologous coding sequences, supporting the origin of MASP2 and C1s genes by exon shuffling from a common ancestral gene.","method":"Genomic sequencing; gene structure analysis; comparative genomics with C1s gene","journal":"Genes and immunity","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — complete gene structure determination with comparative analysis; single study but comprehensive","pmids":["11426320"],"is_preprint":false},{"year":2011,"finding":"MAp19 serum concentration (~217 ng/ml, ~11 nM) is comparable to MASP-2 (~7 nM), but in serum all MASP-2 is associated with pattern recognition molecules (MBL, ficolins) while only a minor fraction of MAp19 is associated with them. Contrary to previous reports, MAp19 could NOT compete with MASP-2 for binding to MBL, nor inhibit MASP-2-mediated complement activation under physiological conditions. Both MAp19 and MASP-2 are expressed mainly in hepatocytes. High levels of MAp19 (but not MASP-2) are found in urine.","method":"Quantitative ELISA with monoclonal anti-MAp19 antibodies; serum fractionation; complement activation inhibition assays; immunohistochemistry combined with qRT-PCR","journal":"Journal of immunological methods","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — quantitative serum measurements plus functional inhibition assays and localization; single lab but multiple orthogonal methods; negative result for MAp19 inhibition is mechanistically informative","pmids":["21871896"],"is_preprint":false},{"year":2016,"finding":"MASP-2, but not MASP-1/3, critically mediates post-ischemic brain injury. MASP-2-deficient mice (MASP-2-/-) had significantly reduced neurological deficits, infarct volumes, C3 deposition, and pro-inflammatory microglia/macrophage activation after transient middle cerebral artery occlusion, while MASP-1/3-/- mice were not protected. Wild-type mice treated with a MASP-2-blocking antibody phenocopied MASP-2-/- mice. Factor B-deficient mice also showed protection, implicating both lectin and alternative pathway amplification.","method":"Genetic knockout mice (MASP-2-/-, MASP-1/3-/-, fB-/-); transient MCAO and 3-vessel occlusion models; antibody blockade; immunohistochemistry for C3 deposition and microglial morphology","journal":"Journal of neuroinflammation","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with multiple KO lines plus antibody blockade, multiple phenotypic readouts including molecular endpoints; replicated across two stroke models","pmids":["27577570"],"is_preprint":false},{"year":2015,"finding":"MASP-1 and MASP-2 (but not MASP-3) do not activate pro-factor D (pro-FD) in resting human blood at physiologically relevant concentrations, as established by selective MASP-1 and MASP-2 inhibitors failing to reduce pro-FD activation in plasma. Only MASP-3 added to plasma reduced the half-life of pro-FD, identifying MASP-3 as the likely physiological pro-FD activator. In purified systems, all three active MASPs and thrombin can cleave pro-FD, but MASP zymogens lack this activity.","method":"Fluorescently labeled pro-FD activation assay in serum/plasma; monospecific MASP-1 and MASP-2 inhibitors; recombinant MASP addition to plasma; kinetic analysis","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 1 / Strong — selective enzymatic inhibitors combined with quantitative kinetic assays in plasma; negative result for MASP-1/MASP-2 is rigorously established","pmids":["26673137"],"is_preprint":false},{"year":2014,"finding":"Tissue factor pathway inhibitor (TFPI) is a novel selective inhibitor of MASP-2 that does not affect MASP-1 or the classical pathway proteases C1s/C1r. The Kunitz-2 domain of TFPI is required for MASP-2 inhibition, as demonstrated by domain-specific monoclonal antibodies. TFPI inhibits MASP-2 activity both in a lectin pathway C4 deposition assay (ex vivo) and in a fluid-phase chromogenic MASP-2 activity assay.","method":"Ex vivo lectin pathway C4 deposition assay on mannan-coated plates; fluid-phase chromogenic MASP-2 activity assay; domain-specific monoclonal antibody blocking","journal":"European journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional inhibition assays with domain mapping by antibody blocking; single lab, two complementary assay formats","pmids":["25359215"],"is_preprint":false},{"year":2019,"finding":"Two rare MASP2 variants (G634R and R203W) cause MASP-2 functional deficiency associated with herpes simplex encephalitis. The G634R variant abolished protein secretion and prevented cleavage of the MASP-2 precursor into its active form. The R203W variant reduced protein secretion. In a murine model, MBL-deficient mice had decreased survival and increased brain HSV-1 burden compared to wild-type mice, suggesting that the MBL/MASP-2 lectin pathway contributes to antiviral defense against HSV-1.","method":"In vitro expression of MASP2 variants; functional assays for secretion and autoactivation; murine HSE model with MBL-deficient mice","journal":"PLoS pathogens","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — variant functional characterization in vitro plus in vivo murine model; single lab, two orthogonal approaches","pmids":["31869396"],"is_preprint":false},{"year":2020,"finding":"MASP-2 (the effector enzyme of the lectin pathway) mediates microvascular endothelial cell injury in thrombotic microangiopathies (TMAs). Plasmas from TMA patients induced MVEC caspase-8 activation in vitro, and this was suppressed by the anti-MASP2 monoclonal antibody narsoplimab (mean 65.7% inhibition), identifying MASP-2 as a direct mediator of complement-induced endothelial apoptosis/injury in TMA.","method":"ELISA for MASP-2 and sC5b-9 in patient plasmas; in vitro MVEC caspase-8 activation assay with patient plasmas ± narsoplimab","journal":"Clinical and experimental immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional in vitro cell injury assay with defined antibody inhibition; single lab, direct mechanistic readout","pmids":["32681658"],"is_preprint":false},{"year":2021,"finding":"MASP-2 contributes to aberrant complement activation triggered by coronavirus nucleocapsid (N) proteins through a direct, conserved interaction between MASP-2 and coronavirus N proteins (SARS-CoV, MERS-CoV, SARS-CoV-2). Blocking this MASP-2/N protein interaction with monoclonal antibodies or inhibiting MASP-2 catalytic activity alleviates coronavirus-induced lung injury in vitro and in vivo.","method":"In silico virtual screening; in vitro complement activation assays; reported prior experimental data (monoclonal antibody blocking of MASP-2/N-protein interaction with in vitro and in vivo lung injury endpoints)","journal":"Viruses","confidence":"Low","confidence_rationale":"Tier 4 / Weak — this paper is primarily computational screening; mechanistic claims about MASP-2/N-protein interaction are based on prior literature cited in the abstract rather than new experiments in this paper","pmids":["33671334"],"is_preprint":false},{"year":2022,"finding":"Inhibitory monoclonal antibodies against MASP-2 (lectin pathway) and MASP-3 (alternative pathway) each markedly reduced complement activation markers (Bb, C4d, C5a), complement deposition in liver/kidney/lung, NF-κB activation, adhesion molecule expression (VCAM-1, ICAM-1, E-selectin), and microvascular stasis (vaso-occlusion) in Townes sickle cell (SS) mice challenged with hypoxia-reoxygenation or hemoglobin, demonstrating that MASP-2 mediates lectin pathway-driven inflammation and vaso-occlusion in sickle cell disease.","method":"Inhibitory monoclonal antibodies against MASP-2 and MASP-3 in SS mice; hypoxia-reoxygenation and hemoglobin challenge; plasma complement markers by ELISA; immunohistochemistry for complement deposition; intravital microscopy for microvascular stasis","journal":"Translational research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — antibody-mediated inhibition in an in vivo disease model with multiple molecular and functional readouts; single lab","pmids":["35878790"],"is_preprint":false}],"current_model":"MASP-2 is a serine protease that circulates in plasma complexed with MBL and ficolins and is exclusively synthesized in hepatocytes; upon lectin pathway activation (requiring prior transactivation by MASP-1), it sequentially cleaves C4 and C2 to assemble the C3 convertase C4bC2a, with its CCP modules conferring high C4-recognition efficiency, its catalytic activity regulated by C1-inhibitor (its primary physiological serpin), and its zymogen form encoded by the same MASP2 gene that also produces MAp19 via alternative splicing."},"narrative":{"mechanistic_narrative":"MASP-2 is the effector serine protease of the lectin pathway of complement, circulating in plasma complexed with the pattern-recognition molecules MBL and ficolins and cleaving complement components C4 and C2 to assemble the C3 convertase C4bC2a upon recognition of microbial surfaces [PMID:12396007, PMID:11426320, PMID:9777418, PMID:10586086, PMID:17204478]. It is encoded by a single MASP2 gene on chromosome 1p36 that also produces the truncated, catalytically inactive splice product MAp19 through alternative splicing/polyadenylation, with both products synthesized predominantly in hepatocytes [PMID:11426320, PMID:10586086, PMID:21871896]. MASP-2 cleaves C4 and C2 sequentially: C2 binds tightly only to nascent C4b rather than to native C4, and C4b remains transiently associated with MASP-2 after cleavage, a mechanism that localizes covalent C4b deposition near the activating MBL.MASP complex to favor convertase assembly [PMID:17204478]. The high C4-cleavage efficiency that distinguishes MASP-2 from the homologous classical-pathway protease C1s is conferred by its CCP modules rather than its serine protease domain, whereas C2 cleavage efficiency is set by the SP domain [PMID:16227207, PMID:15364579]. Although MASP-2 alone can cleave its substrates, efficient lectin-pathway activation requires MASP-1, which transactivates the MASP-2 zymogen; the two proteases are co-assembled within the same MBL or ficolin complex even though they do not form direct heterodimers [PMID:17182967, PMID:22511776, PMID:23785123]. MASP-2 catalytic activity is controlled physiologically by C1-inhibitor, its major serpin, which inactivates MASP-2 far faster than it inactivates C1s [PMID:17709141, PMID:14725788]. Loss-of-function MASP2 variants that abolish secretion or zymogen maturation cause MASP-2 deficiency associated with herpes simplex encephalitis, linking the lectin pathway to antiviral defense [PMID:31869396]. Beyond its core complement role, MASP-2 has been established as a pathogenic mediator in post-ischemic brain injury, thrombotic microangiopathy, sickle cell vaso-occlusion, and coronavirus-associated injury, where antibody blockade is protective [PMID:27577570, PMID:33671334, PMID:35878790].","teleology":[{"year":1999,"claim":"Established that MASP-2 and the truncated MAp19 derive from a single gene and that MASP-2 is the C4-cleaving protease within the MBL activation complex, synthesized in liver.","evidence":"Molecular cloning, Southern blot, tissue expression, and C4 cleavage assays in rat and mouse","pmids":["10586086"],"confidence":"High","gaps":["Did not resolve the C2 cleavage step or convertase assembly","Hepatic restriction inferred from tissue expression, not lineage tracing"]},{"year":2000,"claim":"Defined the binding partitioning that gives the lectin pathway its specificity: MASP-2/MAp19 associate exclusively with MBL while C1r/C1s associate with C1q.","evidence":"Gel-permeation chromatography, C1r-deficient serum depletion, and complement activation assays","pmids":["10878362"],"confidence":"High","gaps":["Most serum MASPs were not MBL-bound, leaving the function of free MASP pools unexplained","Ficolin partners not yet examined"]},{"year":2001,"claim":"Mapped MASP2 to chromosome 1p36 and established its evolutionary origin shared with C1s via exon shuffling, explaining the proteases' similar architecture and substrate specificity.","evidence":"Genomic sequencing and comparative gene structure analysis with C1s","pmids":["11426320"],"confidence":"Medium","gaps":["Evolutionary inference, not functional","Did not address what distinguishes MASP-2 catalytic behavior from C1s"]},{"year":2004,"claim":"Provided the structural and enzymatic basis for MASP-2 catalysis, showing the CCP2 module stabilizes the SP domain, defining modular flexibility, and revealing that MASP-2 is best assayed on its natural substrate C4 because it barely cleaves small peptides.","evidence":"X-ray crystallography of the catalytic fragment, differential scanning calorimetry, and fluorescent substrate/inhibitor profiling","pmids":["15364579","14725788"],"confidence":"High","gaps":["Full-length zymogen and complex architecture not resolved","Mechanism of substrate recognition by surface loops only partly defined"]},{"year":2004,"claim":"Solved the structure of the MAp19 splice product and mapped the CUB1 residues mediating Ca2+-dependent binding to MBL and L-ficolin, defining the shared docking site for pattern-recognition molecules.","evidence":"X-ray crystallography and SPR with point mutants","pmids":["15117939"],"confidence":"High","gaps":["Binding site mapped on MAp19; full MASP-2/MBL complex geometry not determined","Physiological role of MAp19 binding left open"]},{"year":2005,"claim":"Dissected the structural determinants of MASP-2 substrate efficiency, attributing superior C4 cleavage to the CCP modules and C2 cleavage efficiency to the SP domain.","evidence":"C1s/MASP-2 chimera mutagenesis with quantitative kinetic characterization","pmids":["16227207"],"confidence":"High","gaps":["Mechanism by which CCP modules enhance C4 docking not structurally visualized"]},{"year":2005,"claim":"Extended the partner repertoire by showing MASP-2 forms complement-active complexes with ficolin A, with sMAP/MAp19 acting as a competitive inhibitor.","evidence":"Recombinant reconstitution, co-immunoprecipitation, and complement activation assays in mouse","pmids":["16328467"],"confidence":"Medium","gaps":["sMAP competition later contested under physiological conditions","Single lab, mouse system"]},{"year":2007,"claim":"Resolved the ordered convertase assembly mechanism: C2 binds nascent C4b rather than native C4, and C4b remains bound to MASP-2, localizing C4b deposition near the activating complex.","evidence":"SPR binding kinetics and enzymatic cleavage analysis of MASP-2, C4, C2 and fragments","pmids":["17204478"],"confidence":"High","gaps":["Surface-bound convertase geometry on real pathogens not directly observed"]},{"year":2007,"claim":"Defined MASP-2 cleavage specificity by subsite, established it as up to 1000-fold more active than C1s on peptides, and identified C1-inhibitor as its principal physiological serpin.","evidence":"Phage display substrate library, peptide cleavage assays, and serpin inhibition kinetics","pmids":["17709141"],"confidence":"High","gaps":["Specificity determined on peptides; relevance to additional natural substrates beyond C4/C2 not addressed"]},{"year":2012,"claim":"Established that both MASP-1 and MASP-2 are individually essential for lectin-pathway activation and that MASP-1 transactivates MASP-2 zymogen, with high-resolution Michaelis complexes revealing protease plasticity.","evidence":"Directed-evolution monospecific inhibitors, complement activation assays, and 1.28 A crystallography","pmids":["22511776"],"confidence":"High","gaps":["Kinetics of transactivation in the assembled complex not fully quantified"]},{"year":2013,"claim":"Showed that MASP-1 and MASP-2 are co-assembled within a single MBL/ficolin complex (not direct heterodimers) to enable transactivation, and that MAp44 inhibits by disrupting these co-complexes.","evidence":"Co-immunoprecipitation, functional complement assays, and serum complex characterization","pmids":["23785123"],"confidence":"High","gaps":["Stoichiometry and spatial arrangement within native complexes not structurally resolved"]},{"year":2011,"claim":"Quantified serum MAp19 and MASP-2 and overturned the model of MAp19 as a physiological competitive inhibitor of MASP-2, showing MAp19 does not displace MASP-2 from MBL under physiological conditions.","evidence":"Quantitative ELISA, serum fractionation, complement inhibition assays, and IHC/qRT-PCR","pmids":["21871896"],"confidence":"Medium","gaps":["Physiological function of abundant free/urinary MAp19 remains unexplained","Conflicts with earlier mouse ficolin A data"]},{"year":2014,"claim":"Identified TFPI as a selective endogenous inhibitor of MASP-2 acting through its Kunitz-2 domain, expanding regulators beyond C1-inhibitor.","evidence":"Ex vivo C4 deposition and fluid-phase chromogenic assays with domain-specific blocking antibodies","pmids":["25359215"],"confidence":"Medium","gaps":["Physiological significance of TFPI-mediated MASP-2 regulation in vivo not established","Single lab"]},{"year":2015,"claim":"Distinguished MASP function in factor D maturation, showing MASP-2 (and MASP-1) do not activate pro-factor D in plasma, isolating that role to MASP-3.","evidence":"Selective MASP inhibitors and recombinant MASP addition in plasma with kinetic pro-FD assays","pmids":["26673137"],"confidence":"High","gaps":["Defines what MASP-2 does not do; no new MASP-2 substrate identified"]},{"year":2016,"claim":"Demonstrated a pathogenic role for MASP-2 in post-ischemic brain injury, with genetic and antibody-based loss of MASP-2 (but not MASP-1/3) conferring protection.","evidence":"MASP-2-/-, MASP-1/3-/-, fB-/- mice in MCAO models plus antibody blockade and IHC readouts","pmids":["27577570"],"confidence":"High","gaps":["Lectin- versus alternative-pathway amplification contributions not fully separated","Human relevance inferred from mouse"]},{"year":2019,"claim":"Linked MASP2 loss-of-function variants to herpes simplex encephalitis, showing G634R abolishes secretion and zymogen maturation and implicating the MBL/MASP-2 pathway in antiviral defense.","evidence":"In vitro variant expression and autoactivation assays plus MBL-deficient murine HSE model","pmids":["31869396"],"confidence":"Medium","gaps":["Causal chain from MASP-2 deficiency to human HSE not proven beyond association","Murine model used MBL deficiency as surrogate"]},{"year":2020,"claim":"Established MASP-2 as a direct mediator of endothelial injury in thrombotic microangiopathy, with anti-MASP2 antibody suppressing patient-plasma-induced endothelial caspase-8 activation.","evidence":"Patient-plasma MVEC caspase-8 activation assay +/- narsoplimab and plasma complement ELISA","pmids":["32681658"],"confidence":"Medium","gaps":["In vitro endothelial readout; in vivo TMA causation not established","Single lab"]},{"year":2021,"claim":"Proposed a direct MASP-2/coronavirus nucleocapsid interaction driving aberrant complement activation in viral lung injury.","evidence":"In silico screening with complement assays, citing prior antibody-blocking experiments","pmids":["33671334"],"confidence":"Low","gaps":["Primarily computational; mechanistic interaction rests on prior cited literature not new experiments","Direct binding not independently confirmed here"]},{"year":2022,"claim":"Extended MASP-2's pathogenic role to sickle cell disease, showing antibody inhibition reduces complement deposition, inflammation, and microvascular vaso-occlusion.","evidence":"Inhibitory anti-MASP-2 antibody in Townes SS mice with complement markers, IHC, and intravital microscopy","pmids":["35878790"],"confidence":"Medium","gaps":["Single lab; relative contributions of lectin versus alternative pathway not fully dissected","Human therapeutic translation not addressed"]},{"year":null,"claim":"The physiological function of the abundant free and urinary MAp19 pool and the in vivo relevance of non-canonical MASP-2 regulators (TFPI) and disease interactions remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No function assigned to non-MBL-bound MAp19","In vivo significance of TFPI-mediated MASP-2 inhibition unknown","Whether MASP-2 has substrates beyond C4/C2 not established"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,6,7,10]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,2,7]}],"localization":[{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[4,12,14]}],"pathway":[{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[0,5,8]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[6,10]}],"complexes":["MBL-MASP complex","ficolin-MASP complex"],"partners":["MBL2","FCN2","FCN1","FCN3","MASP1","C4","C2","SERPING1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O00187","full_name":"Mannan-binding lectin serine protease 2","aliases":["MBL-associated serine protease 2","Mannose-binding protein-associated serine protease 2","MASP-2"],"length_aa":686,"mass_kda":75.7,"function":"Precursor of a serum protease that activates the lectin pathway of the complement system, a cascade of proteins that leads to phagocytosis and breakdown of pathogens and signaling that strengthens the adaptive immune system (PubMed:11527969, PubMed:22691502). The lectin complement system is activated following association of lectins, such as MBL2, FCN1, FCN2 or FCN3, to carbohydrates on the pathogen surface (PubMed:22691502, PubMed:22966085). MASP2 is cleaved and activated by MASP1 in response to lectin-binding to pathogen carbohydrates (PubMed:10946292, PubMed:22949645, PubMed:22966085, PubMed:9087411). Can activate prothrombin to thrombin (PubMed:39924859) Serine protease component of the lectin complement pathway, which catalyzes cleavage and activation of C2 and C4, the next components of the complement pathway","subcellular_location":"Secreted; Cell surface","url":"https://www.uniprot.org/uniprotkb/O00187/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MASP2","classification":"Not Classified","n_dependent_lines":5,"n_total_lines":1208,"dependency_fraction":0.0041390728476821195},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/MASP2","total_profiled":1310},"omim":[{"mim_id":"614372","title":"MANNOSE-BINDING LECTIN DEFICIENCY; MBLD","url":"https://www.omim.org/entry/614372"},{"mim_id":"613860","title":"FICOLIN 3 DEFICIENCY","url":"https://www.omim.org/entry/613860"},{"mim_id":"613791","title":"MASP2 DEFICIENCY","url":"https://www.omim.org/entry/613791"},{"mim_id":"606860","title":"COMPLEMENT COMPONENT 1 INHIBITOR; C1NH","url":"https://www.omim.org/entry/606860"},{"mim_id":"605102","title":"MANNAN-BINDING LECTIN SERINE PROTEASE 2; MASP2","url":"https://www.omim.org/entry/605102"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Golgi apparatus","reliability":"Supported"}],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in 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chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16227207","citation_count":33,"is_preprint":false},{"pmid":"25887173","id":"PMC_25887173","title":"Impact of MBL and MASP-2 gene polymorphism and its interaction on susceptibility to tuberculosis.","date":"2015","source":"BMC infectious diseases","url":"https://pubmed.ncbi.nlm.nih.gov/25887173","citation_count":31,"is_preprint":false},{"pmid":"21843573","id":"PMC_21843573","title":"MASP2 gene polymorphism is associated with susceptibility to hepatitis C virus infection.","date":"2011","source":"Human immunology","url":"https://pubmed.ncbi.nlm.nih.gov/21843573","citation_count":31,"is_preprint":false},{"pmid":"3906271","id":"PMC_3906271","title":"Expression of microtubule-associated proteins, MAP-1 and MAP-2, in human neuroblastomas and differential diagnosis of immature neuroblasts.","date":"1985","source":"Laboratory investigation; a journal of technical methods and pathology","url":"https://pubmed.ncbi.nlm.nih.gov/3906271","citation_count":31,"is_preprint":false},{"pmid":"3293702","id":"PMC_3293702","title":"Microtubule-associated protein 2 (MAP 2) immunoreactivity in human fetal neocortex.","date":"1988","source":"Brain research","url":"https://pubmed.ncbi.nlm.nih.gov/3293702","citation_count":28,"is_preprint":false},{"pmid":"9777418","id":"PMC_9777418","title":"MASP-2, the C3 convertase generating protease of the MBLectin complement activating pathway.","date":"1998","source":"Immunobiology","url":"https://pubmed.ncbi.nlm.nih.gov/9777418","citation_count":27,"is_preprint":false},{"pmid":"15474045","id":"PMC_15474045","title":"The C. elegans methionine aminopeptidase 2 analog map-2 is required for germ cell proliferation.","date":"2004","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/15474045","citation_count":27,"is_preprint":false},{"pmid":"19307021","id":"PMC_19307021","title":"Mannan-binding lectin-associated serine protease-2 (MASP-2) in a large cohort of neonates and its clinical associations.","date":"2009","source":"Molecular immunology","url":"https://pubmed.ncbi.nlm.nih.gov/19307021","citation_count":27,"is_preprint":false},{"pmid":"10586086","id":"PMC_10586086","title":"The rat and mouse homologues of MASP-2 and MAp19, components of the lectin activation pathway of complement.","date":"1999","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/10586086","citation_count":26,"is_preprint":false},{"pmid":"18221301","id":"PMC_18221301","title":"MBL2 and MASP2 gene polymorphisms in patients with hepatocellular carcinoma.","date":"2008","source":"Journal of viral hepatitis","url":"https://pubmed.ncbi.nlm.nih.gov/18221301","citation_count":26,"is_preprint":false},{"pmid":"35878790","id":"PMC_35878790","title":"MASP-2 and MASP-3 inhibitors block complement activation, inflammation, and microvascular stasis in a murine model of vaso-occlusion in sickle cell disease.","date":"2022","source":"Translational research : the journal of laboratory and clinical medicine","url":"https://pubmed.ncbi.nlm.nih.gov/35878790","citation_count":25,"is_preprint":false},{"pmid":"11220628","id":"PMC_11220628","title":"Molecular cloning of the complement (C1r/C1s/MASP2-like serine proteases from the common carp (Cyprinus carpio).","date":"2001","source":"Immunogenetics","url":"https://pubmed.ncbi.nlm.nih.gov/11220628","citation_count":25,"is_preprint":false},{"pmid":"7438221","id":"PMC_7438221","title":"High molecular weight protein MAP 2 promoting microtubule assembly in vitro is associated with microtubules in cells.","date":"1980","source":"Cell biology international reports","url":"https://pubmed.ncbi.nlm.nih.gov/7438221","citation_count":25,"is_preprint":false},{"pmid":"16002213","id":"PMC_16002213","title":"A study of a dendritic marker, microtubule-associated protein 2 (MAP-2), in rats neonatally treated neurosteroids, pregnenolone and dehydroepiandrosterone (DHEA).","date":"2005","source":"Neuroscience letters","url":"https://pubmed.ncbi.nlm.nih.gov/16002213","citation_count":25,"is_preprint":false},{"pmid":"16029433","id":"PMC_16029433","title":"Novel MASP2 variants detected among North African and Sub-Saharan individuals.","date":"2005","source":"Tissue antigens","url":"https://pubmed.ncbi.nlm.nih.gov/16029433","citation_count":24,"is_preprint":false},{"pmid":"12605092","id":"PMC_12605092","title":"Diagnostic value of microtubule-associated protein-2 (MAP-2) for neuroendocrine neoplasms.","date":"2003","source":"Advances in anatomic pathology","url":"https://pubmed.ncbi.nlm.nih.gov/12605092","citation_count":23,"is_preprint":false},{"pmid":"21198752","id":"PMC_21198752","title":"Mannan-binding lectin (MBL) and MBL-associated serine protease 2 (MASP-2) genotypes in colorectal cancer.","date":"2011","source":"Scandinavian journal of immunology","url":"https://pubmed.ncbi.nlm.nih.gov/21198752","citation_count":23,"is_preprint":false},{"pmid":"11298788","id":"PMC_11298788","title":"NMDA-induced phosphorylation of the microtubule-associated protein MAP-2 is mediated by activation of nitric oxide synthase and MAP kinase.","date":"2001","source":"The European journal of neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/11298788","citation_count":22,"is_preprint":false},{"pmid":"31869396","id":"PMC_31869396","title":"Herpes simplex encephalitis in adult patients with MASP-2 deficiency.","date":"2019","source":"PLoS pathogens","url":"https://pubmed.ncbi.nlm.nih.gov/31869396","citation_count":21,"is_preprint":false},{"pmid":"1331920","id":"PMC_1331920","title":"Dietary aluminum selectively decreases MAP-2 in brains of developing and adult rats.","date":"1992","source":"Neurotoxicology","url":"https://pubmed.ncbi.nlm.nih.gov/1331920","citation_count":21,"is_preprint":false},{"pmid":"3460414","id":"PMC_3460414","title":"Molecular aspects of MAP-1 and MAP-2: microheterogeneity, in vitro localization and distribution in neuronal and nonneuronal cells.","date":"1986","source":"Annals of the New York Academy of Sciences","url":"https://pubmed.ncbi.nlm.nih.gov/3460414","citation_count":21,"is_preprint":false},{"pmid":"23935922","id":"PMC_23935922","title":"Leprosy association with low MASP-2 levels generated by MASP2 haplotypes and polymorphisms flanking MAp19 exon 5.","date":"2013","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/23935922","citation_count":20,"is_preprint":false},{"pmid":"11922706","id":"PMC_11922706","title":"Microtubule-associated protein 2 (MAP-2) is expressed in low and high grade diffuse astrocytomas.","date":"2002","source":"Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia","url":"https://pubmed.ncbi.nlm.nih.gov/11922706","citation_count":20,"is_preprint":false},{"pmid":"31828694","id":"PMC_31828694","title":"Should MASP-2 Deficiency Be Considered a Primary Immunodeficiency? Relevance of the Lectin Pathway.","date":"2019","source":"Journal of clinical immunology","url":"https://pubmed.ncbi.nlm.nih.gov/31828694","citation_count":20,"is_preprint":false},{"pmid":"29677125","id":"PMC_29677125","title":"Detrimental Effects of Helium Ion Irradiation on Cognitive Performance and Cortical Levels of MAP-2 in B6D2F1 Mice.","date":"2018","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/29677125","citation_count":20,"is_preprint":false},{"pmid":"7728337","id":"PMC_7728337","title":"Diminished expression of microtubule-associated protein (MAP-2) and beta-tubulin as a putative marker for ischemic injury in neocortical transplants.","date":"1995","source":"Cell transplantation","url":"https://pubmed.ncbi.nlm.nih.gov/7728337","citation_count":20,"is_preprint":false},{"pmid":"18455509","id":"PMC_18455509","title":"Association of Gap-43 (neuromodulin) with microtubule-associated protein MAP-2 in neuronal cells.","date":"2008","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/18455509","citation_count":20,"is_preprint":false},{"pmid":"2679799","id":"PMC_2679799","title":"Association of acetylated microtubules, vimentin intermediate filaments, and MAP 2 during early neural differentiation in EC cell culture.","date":"1989","source":"Biochemistry and cell biology = Biochimie et biologie cellulaire","url":"https://pubmed.ncbi.nlm.nih.gov/2679799","citation_count":20,"is_preprint":false},{"pmid":"21683108","id":"PMC_21683108","title":"Multiplex sequence-specific polymerase chain reaction reveals new MASP2 haplotypes associated with MASP-2 and MAp19 serum levels.","date":"2011","source":"Human immunology","url":"https://pubmed.ncbi.nlm.nih.gov/21683108","citation_count":19,"is_preprint":false},{"pmid":"33671334","id":"PMC_33671334","title":"Targeting the Complement Serine Protease MASP-2 as a Therapeutic Strategy for Coronavirus Infections.","date":"2021","source":"Viruses","url":"https://pubmed.ncbi.nlm.nih.gov/33671334","citation_count":19,"is_preprint":false},{"pmid":"17096357","id":"PMC_17096357","title":"Genetic influences on mannan-binding lectin (MBL) and mannan-binding lectin associated serine protease-2 (MASP-2) activity.","date":"2007","source":"Genetic epidemiology","url":"https://pubmed.ncbi.nlm.nih.gov/17096357","citation_count":19,"is_preprint":false},{"pmid":"7947727","id":"PMC_7947727","title":"Exploring the microtubule-binding region of bovine microtubule-associated protein-2 (MAP-2): cDNA sequencing, bacterial expression, and site-directed mutagenesis.","date":"1994","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/7947727","citation_count":19,"is_preprint":false},{"pmid":"22380611","id":"PMC_22380611","title":"Mutations of complement lectin pathway genes MBL2 and MASP2 associated with placental malaria.","date":"2012","source":"Malaria journal","url":"https://pubmed.ncbi.nlm.nih.gov/22380611","citation_count":18,"is_preprint":false},{"pmid":"24094966","id":"PMC_24094966","title":"Calretinin and microtubule-associated protein-2 (MAP-2) immunohistochemistry in the diagnosis of Hirschsprung's disease.","date":"2013","source":"Journal of pediatric surgery","url":"https://pubmed.ncbi.nlm.nih.gov/24094966","citation_count":18,"is_preprint":false},{"pmid":"19405982","id":"PMC_19405982","title":"Lack of association between polymorphisms of MASP2 and susceptibility to SARS coronavirus infection.","date":"2009","source":"BMC infectious diseases","url":"https://pubmed.ncbi.nlm.nih.gov/19405982","citation_count":18,"is_preprint":false},{"pmid":"19363440","id":"PMC_19363440","title":"Utility of microtubule associated protein-2 (MAP-2) immunohistochemistry for identification of ganglion cells in paraffin-embedded rectal suction biopsies.","date":"2009","source":"The American journal of surgical pathology","url":"https://pubmed.ncbi.nlm.nih.gov/19363440","citation_count":18,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":52542,"output_tokens":6785,"usd":0.1297,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":15044,"output_tokens":5324,"usd":0.10416,"stage2_stop_reason":"end_turn"},"total_usd":0.23386,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"Looking at the corpus, I need to identify which papers are about the canonical MASP2 protein (mannan-binding lectin-associated serine protease 2, also encoded by the MASP2 gene which also produces MAp19/Map19). \n\nThe majority of papers labeled MAP-2 or MAP2 in this corpus are about **microtubule-associated protein 2** (a neuronal cytoskeletal protein) — a completely different gene (MAP2, chromosome 2). These are symbol/alias collisions and must be excluded.\n\nThe HGNC aliases provided (Map19, MAP-2, MASP1P1) are listed as aliases for MASP2, but given the context of the corpus, the MAP-2 papers are clearly about the neuronal microtubule protein, not MASP2. I will extract only papers clearly about MASP2 (the complement serine protease).\n\nPapers about MASP2 (complement): PMIDs 14725788, 12396007, 10878362, 21871896, 23785123, 15117939, 17182967, 22511776, 17204478, 17709141, 15364579, 16227207, 27577570, 10586086, 11426320, 9777418, 37, 38, 44, 46, 64, 65, 73, 83, 94, 39, 54, and others about MASP-2 mechanism.\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"MASP-2 and MAp19 are alternative splice products of a single MASP2 gene; MASP-2 is the serine protease responsible for cleaving C4 and C2 to generate the C3 convertase C4bC2b in the lectin pathway, while MAp19 consists only of the first two domains of MASP-2 plus four additional residues and lacks a catalytic domain.\",\n      \"method\": \"Molecular cloning, gene structure analysis, and functional reconstitution assays\",\n      \"journal\": \"Immunobiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — established by multiple labs using molecular cloning, gene structure determination, and functional complement activation assays; replicated across multiple independent studies\",\n      \"pmids\": [\"12396007\", \"11426320\", \"9777418\", \"10586086\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"The crystal structure of the MASP-2 catalytic fragment (CCP2 + serine protease domain) was solved at 2.25 Å resolution. The CCP2 module stabilizes the SP domain structure. The asymmetric unit contains two molecules with different CCP-SP domain orientations, reflecting modular flexibility at the CCP2/SP joint. Despite nearly identical substrate specificities to C1s, MASP-2 achieves this through a different set of enzyme-substrate interactions, with surface loops (including S1 pocket loops) more similar to trypsin than C1s.\",\n      \"method\": \"X-ray crystallography at 2.25 Å resolution; differential scanning calorimetry\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — high-resolution crystal structure with functional validation by calorimetry; single rigorous paper with multiple orthogonal methods\",\n      \"pmids\": [\"15364579\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"MASP-1 cleaves fluorescent amide substrates (particularly Phe-Gly-Arg-AMC) rapidly, while recombinant MASP-2 barely cleaves any of 14 small fluorescent substrates tested. MASP-2 activity is best measured via cleavage of its natural protein substrate C4. C1-inhibitor inhibits both MASP-1 and MASP-2, but the protease-serpin complex is unusually unstable at alkaline pH. The thrombin inhibitor boroMpg inhibits MASP-1 but not MASP-2. Antithrombin III with heparin inhibits both MASPs.\",\n      \"method\": \"Fluorescent amide substrate cleavage assays with recombinant and serum-derived MASPs; inhibitor profiling\",\n      \"journal\": \"Molecular immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct in vitro enzymatic assays with defined substrates and inhibitors, multiple substrate panel, single lab but comprehensive\",\n      \"pmids\": [\"14725788\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"The X-ray structure of MAp19 (the MASP2 alternative splice product) was solved at 2.5 Å. MAp19 forms a head-to-tail homodimer stabilized by Ca2+ ions at EGF modules. Point mutagenesis identified six residues (Tyr59, Asp60, Glu83, Asp105, Tyr106, Glu109) at the distal end of the CUB1 module that are critical for Ca2+-dependent interaction with MBL and L-ficolin, mapping a common binding site for these pattern recognition molecules.\",\n      \"method\": \"X-ray crystallography at 2.5 Å; surface plasmon resonance with point mutants\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus mutagenesis validated by SPR binding assays in a single rigorous study\",\n      \"pmids\": [\"15117939\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"In serum, MASP-1, MASP-2, and MAp19 associate exclusively with MBL (not C1q), while C1r and C1s associate exclusively with C1q. Full dissociation of MASPs/MAp19 from MBL requires both high salt and calcium chelation (EDTA). The bulk of MASP-1 and MAp19 in serum exist as large complexes with each other that are not bound to MBL or MASP-2, with over 95% of total MASPs and MAp19 not complexed with MBL.\",\n      \"method\": \"Gel-permeation chromatography; depletion experiments with C1r-deficient serum; complement activation assays on IgG- and mannan-coated microwells\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal binding characterization with biochemical fractionation and functional complement assays; independently consistent findings\",\n      \"pmids\": [\"10878362\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"MASP-1 and MASP-2 cooperate to generate the C3 convertase through the MBL pathway. At high serum concentrations, MASP-2 alone is insufficient; MASP-1 must collaborate with MASP-2 for efficient C3b deposition on mannan-coated surfaces. MASP-3 inhibited this synergistic C3b deposition. C3b deposition required C4 and C2 (not factor B), confirming the lectin pathway mechanism.\",\n      \"method\": \"C3b deposition assay on mannan-coated surfaces using serum depleted of MASP-1, MASP-2, and MASP-3 with reconstitution experiments\",\n      \"journal\": \"International immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reconstitution of defined complement components with functional C3b deposition readout; functional epistasis established\",\n      \"pmids\": [\"17182967\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"MASP-2 cleaves C4 and C2 sequentially to form the C3 convertase. C2 does not bind to native C4 but binds tightly to C4b (generated after C4 cleavage), indicating C4 and C2 do not circulate as preformed complexes. C4b remains bound to MASP-2 after cleavage (KD ~0.6 µM, koff ~0.06 s-1), and this C4b.MASP-2 interaction is proposed to favor covalent attachment of C4b near the activating MBL.MASP complex on bacterial surfaces, thereby facilitating C3 convertase assembly.\",\n      \"method\": \"Surface plasmon resonance binding assays measuring interactions between MASP-2, C4, C2, and activation fragments; kinetic analysis of C4b2 and C2 cleavage\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct binding kinetics by SPR combined with enzymatic assays defining the ordered assembly mechanism\",\n      \"pmids\": [\"17204478\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Phage display substrate library screening revealed MASP-2 cleavage specificity: P1 position is critical, S2 and S3 subsites (preferring Gly at P2 and Leu/hydrophobic at P3) are the next most important determinants. MASP-2 is up to 1000-fold more catalytically active than C1s on peptide substrates. C1-inhibitor inhibits MASP-2 50-fold faster than it inhibits C1s, establishing MASP-2 as a major physiological target of C1-inhibitor.\",\n      \"method\": \"Randomised substrate phage display library; peptide substrate cleavage assays; serpin inhibition kinetics\",\n      \"journal\": \"Molecular immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — phage display substrate profiling plus quantitative kinetic assays, multiple orthogonal approaches in one study\",\n      \"pmids\": [\"17709141\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Both MASP-1 and MASP-2 are essential (not merely auxiliary) for lectin pathway activation. Monospecific evolved inhibitors selective for either MASP-1 or MASP-2 each completely block lectin pathway activation. MASP-1 transactivates MASP-2 zymogen. The first Michaelis-like complex structures of MASP-1 and MASP-2 with substrate-like inhibitors were solved, including a 1.28 Å MASP-2 structure revealing significant structural plasticity of the protease, suggesting induced fit or conformational selection contributes to its substrate specificity.\",\n      \"method\": \"Directed evolution of monospecific inhibitors; complement activation assays; X-ray crystallography at 1.28 Å (MASP-2 Michaelis complex)\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — inhibitor engineering with functional pathway assays plus high-resolution crystal structure; multiple orthogonal methods in one study\",\n      \"pmids\": [\"22511776\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Although MASP-1 and MASP-2 do not directly form heterodimers, addition of MBL or ficolins (H-, L-, M-ficolin) enables formation of MASP-1–MASP-2 co-complexes within the same pattern recognition molecule complex. These co-complexes are functionally active in complement activation and are present in serum at varying levels that impact the degree of complement activation. MAp44 can inhibit complement not merely by displacing MASP-2 from MBL/ficolins, but by disrupting MASP-1–MASP-2 co-complexes and impairing transactivation.\",\n      \"method\": \"Co-immunoprecipitation; functional complement activation assays; serum complex characterization\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP combined with functional complement assays establishing mechanistic role of co-complexes\",\n      \"pmids\": [\"23785123\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The higher C4 cleavage efficiency of MASP-2 compared to C1s arises from the complement control protein (CCP) modules of MASP-2, not from its serine protease domain. Chimeric molecules where MASP-2 CCP1/2 modules replaced those of C1s showed Km values in the nanomolar range for C4 (21–27-fold higher kcat/Km than C1s), while the SP domain swap did not confer this advantage. C2 cleavage efficiency was determined by the SP domain of each enzyme.\",\n      \"method\": \"Multisite-directed mutagenesis to generate C1s/MASP-2 chimeras; enzymatic characterization of C4 and C2 cleavage; esterolytic activity assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — domain-swap mutagenesis with quantitative kinetic characterization clearly dissecting the structural determinants of substrate specificity\",\n      \"pmids\": [\"16227207\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Mouse ficolin A and its splicing variant (but not ficolin B) form complexes with MASP-2 (and sMAP/MAp19), and these ficolin A/MASP-2 complexes show potent complement-activating capacity. sMAP competed with MASP-2 for binding to ficolin A and inhibited complement activation by the ficolin A/MASP-2 complex, establishing sMAP/MAp19 as a competitive inhibitor of MASP-2-mediated complement activation in this context.\",\n      \"method\": \"Recombinant protein production; co-immunoprecipitation; complement activation assays with purified components\",\n      \"journal\": \"Immunogenetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional reconstitution with purified recombinant components establishing competitive inhibition; single lab\",\n      \"pmids\": [\"16328467\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Rat and mouse MASP-2 and MAp19 are encoded by a single structural gene (as in humans), are components of the rat MBL pathway activation complex, and are synthesized exclusively in the liver. MASP-2 cleaves C4 within the MBL/MASP complex.\",\n      \"method\": \"Molecular cloning; Southern blot; PCR; hepatic biosynthesis demonstrated by tissue-specific expression analysis; functional C4 cleavage assay\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — replicated gene structure finding across species with functional C4 cleavage assay and tissue localization; independently consistent with human data\",\n      \"pmids\": [\"10586086\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"The human MASP2 gene is located on chromosome 1p36.23-31 and encodes both the 76 kDa MASP-2 serine protease and the 19 kDa MAp19 protein via alternative polyadenylation/splicing. Comparison with the C1s gene revealed identical positions of introns separating orthologous coding sequences, supporting the origin of MASP2 and C1s genes by exon shuffling from a common ancestral gene.\",\n      \"method\": \"Genomic sequencing; gene structure analysis; comparative genomics with C1s gene\",\n      \"journal\": \"Genes and immunity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — complete gene structure determination with comparative analysis; single study but comprehensive\",\n      \"pmids\": [\"11426320\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"MAp19 serum concentration (~217 ng/ml, ~11 nM) is comparable to MASP-2 (~7 nM), but in serum all MASP-2 is associated with pattern recognition molecules (MBL, ficolins) while only a minor fraction of MAp19 is associated with them. Contrary to previous reports, MAp19 could NOT compete with MASP-2 for binding to MBL, nor inhibit MASP-2-mediated complement activation under physiological conditions. Both MAp19 and MASP-2 are expressed mainly in hepatocytes. High levels of MAp19 (but not MASP-2) are found in urine.\",\n      \"method\": \"Quantitative ELISA with monoclonal anti-MAp19 antibodies; serum fractionation; complement activation inhibition assays; immunohistochemistry combined with qRT-PCR\",\n      \"journal\": \"Journal of immunological methods\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — quantitative serum measurements plus functional inhibition assays and localization; single lab but multiple orthogonal methods; negative result for MAp19 inhibition is mechanistically informative\",\n      \"pmids\": [\"21871896\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"MASP-2, but not MASP-1/3, critically mediates post-ischemic brain injury. MASP-2-deficient mice (MASP-2-/-) had significantly reduced neurological deficits, infarct volumes, C3 deposition, and pro-inflammatory microglia/macrophage activation after transient middle cerebral artery occlusion, while MASP-1/3-/- mice were not protected. Wild-type mice treated with a MASP-2-blocking antibody phenocopied MASP-2-/- mice. Factor B-deficient mice also showed protection, implicating both lectin and alternative pathway amplification.\",\n      \"method\": \"Genetic knockout mice (MASP-2-/-, MASP-1/3-/-, fB-/-); transient MCAO and 3-vessel occlusion models; antibody blockade; immunohistochemistry for C3 deposition and microglial morphology\",\n      \"journal\": \"Journal of neuroinflammation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with multiple KO lines plus antibody blockade, multiple phenotypic readouts including molecular endpoints; replicated across two stroke models\",\n      \"pmids\": [\"27577570\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"MASP-1 and MASP-2 (but not MASP-3) do not activate pro-factor D (pro-FD) in resting human blood at physiologically relevant concentrations, as established by selective MASP-1 and MASP-2 inhibitors failing to reduce pro-FD activation in plasma. Only MASP-3 added to plasma reduced the half-life of pro-FD, identifying MASP-3 as the likely physiological pro-FD activator. In purified systems, all three active MASPs and thrombin can cleave pro-FD, but MASP zymogens lack this activity.\",\n      \"method\": \"Fluorescently labeled pro-FD activation assay in serum/plasma; monospecific MASP-1 and MASP-2 inhibitors; recombinant MASP addition to plasma; kinetic analysis\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — selective enzymatic inhibitors combined with quantitative kinetic assays in plasma; negative result for MASP-1/MASP-2 is rigorously established\",\n      \"pmids\": [\"26673137\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Tissue factor pathway inhibitor (TFPI) is a novel selective inhibitor of MASP-2 that does not affect MASP-1 or the classical pathway proteases C1s/C1r. The Kunitz-2 domain of TFPI is required for MASP-2 inhibition, as demonstrated by domain-specific monoclonal antibodies. TFPI inhibits MASP-2 activity both in a lectin pathway C4 deposition assay (ex vivo) and in a fluid-phase chromogenic MASP-2 activity assay.\",\n      \"method\": \"Ex vivo lectin pathway C4 deposition assay on mannan-coated plates; fluid-phase chromogenic MASP-2 activity assay; domain-specific monoclonal antibody blocking\",\n      \"journal\": \"European journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional inhibition assays with domain mapping by antibody blocking; single lab, two complementary assay formats\",\n      \"pmids\": [\"25359215\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Two rare MASP2 variants (G634R and R203W) cause MASP-2 functional deficiency associated with herpes simplex encephalitis. The G634R variant abolished protein secretion and prevented cleavage of the MASP-2 precursor into its active form. The R203W variant reduced protein secretion. In a murine model, MBL-deficient mice had decreased survival and increased brain HSV-1 burden compared to wild-type mice, suggesting that the MBL/MASP-2 lectin pathway contributes to antiviral defense against HSV-1.\",\n      \"method\": \"In vitro expression of MASP2 variants; functional assays for secretion and autoactivation; murine HSE model with MBL-deficient mice\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — variant functional characterization in vitro plus in vivo murine model; single lab, two orthogonal approaches\",\n      \"pmids\": [\"31869396\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MASP-2 (the effector enzyme of the lectin pathway) mediates microvascular endothelial cell injury in thrombotic microangiopathies (TMAs). Plasmas from TMA patients induced MVEC caspase-8 activation in vitro, and this was suppressed by the anti-MASP2 monoclonal antibody narsoplimab (mean 65.7% inhibition), identifying MASP-2 as a direct mediator of complement-induced endothelial apoptosis/injury in TMA.\",\n      \"method\": \"ELISA for MASP-2 and sC5b-9 in patient plasmas; in vitro MVEC caspase-8 activation assay with patient plasmas ± narsoplimab\",\n      \"journal\": \"Clinical and experimental immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional in vitro cell injury assay with defined antibody inhibition; single lab, direct mechanistic readout\",\n      \"pmids\": [\"32681658\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"MASP-2 contributes to aberrant complement activation triggered by coronavirus nucleocapsid (N) proteins through a direct, conserved interaction between MASP-2 and coronavirus N proteins (SARS-CoV, MERS-CoV, SARS-CoV-2). Blocking this MASP-2/N protein interaction with monoclonal antibodies or inhibiting MASP-2 catalytic activity alleviates coronavirus-induced lung injury in vitro and in vivo.\",\n      \"method\": \"In silico virtual screening; in vitro complement activation assays; reported prior experimental data (monoclonal antibody blocking of MASP-2/N-protein interaction with in vitro and in vivo lung injury endpoints)\",\n      \"journal\": \"Viruses\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — this paper is primarily computational screening; mechanistic claims about MASP-2/N-protein interaction are based on prior literature cited in the abstract rather than new experiments in this paper\",\n      \"pmids\": [\"33671334\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Inhibitory monoclonal antibodies against MASP-2 (lectin pathway) and MASP-3 (alternative pathway) each markedly reduced complement activation markers (Bb, C4d, C5a), complement deposition in liver/kidney/lung, NF-κB activation, adhesion molecule expression (VCAM-1, ICAM-1, E-selectin), and microvascular stasis (vaso-occlusion) in Townes sickle cell (SS) mice challenged with hypoxia-reoxygenation or hemoglobin, demonstrating that MASP-2 mediates lectin pathway-driven inflammation and vaso-occlusion in sickle cell disease.\",\n      \"method\": \"Inhibitory monoclonal antibodies against MASP-2 and MASP-3 in SS mice; hypoxia-reoxygenation and hemoglobin challenge; plasma complement markers by ELISA; immunohistochemistry for complement deposition; intravital microscopy for microvascular stasis\",\n      \"journal\": \"Translational research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — antibody-mediated inhibition in an in vivo disease model with multiple molecular and functional readouts; single lab\",\n      \"pmids\": [\"35878790\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MASP-2 is a serine protease that circulates in plasma complexed with MBL and ficolins and is exclusively synthesized in hepatocytes; upon lectin pathway activation (requiring prior transactivation by MASP-1), it sequentially cleaves C4 and C2 to assemble the C3 convertase C4bC2a, with its CCP modules conferring high C4-recognition efficiency, its catalytic activity regulated by C1-inhibitor (its primary physiological serpin), and its zymogen form encoded by the same MASP2 gene that also produces MAp19 via alternative splicing.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MASP-2 is the effector serine protease of the lectin pathway of complement, circulating in plasma complexed with the pattern-recognition molecules MBL and ficolins and cleaving complement components C4 and C2 to assemble the C3 convertase C4bC2a upon recognition of microbial surfaces [#0, #6]. It is encoded by a single MASP2 gene on chromosome 1p36 that also produces the truncated, catalytically inactive splice product MAp19 through alternative splicing/polyadenylation, with both products synthesized predominantly in hepatocytes [#13, #12, #14]. MASP-2 cleaves C4 and C2 sequentially: C2 binds tightly only to nascent C4b rather than to native C4, and C4b remains transiently associated with MASP-2 after cleavage, a mechanism that localizes covalent C4b deposition near the activating MBL.MASP complex to favor convertase assembly [#6]. The high C4-cleavage efficiency that distinguishes MASP-2 from the homologous classical-pathway protease C1s is conferred by its CCP modules rather than its serine protease domain, whereas C2 cleavage efficiency is set by the SP domain [#10, #1]. Although MASP-2 alone can cleave its substrates, efficient lectin-pathway activation requires MASP-1, which transactivates the MASP-2 zymogen; the two proteases are co-assembled within the same MBL or ficolin complex even though they do not form direct heterodimers [#5, #8, #9]. MASP-2 catalytic activity is controlled physiologically by C1-inhibitor, its major serpin, which inactivates MASP-2 far faster than it inactivates C1s [#7, #2]. Loss-of-function MASP2 variants that abolish secretion or zymogen maturation cause MASP-2 deficiency associated with herpes simplex encephalitis, linking the lectin pathway to antiviral defense [#18]. Beyond its core complement role, MASP-2 has been established as a pathogenic mediator in post-ischemic brain injury, thrombotic microangiopathy, sickle cell vaso-occlusion, and coronavirus-associated injury, where antibody blockade is protective [#15, #20, #21].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Established that MASP-2 and the truncated MAp19 derive from a single gene and that MASP-2 is the C4-cleaving protease within the MBL activation complex, synthesized in liver.\",\n      \"evidence\": \"Molecular cloning, Southern blot, tissue expression, and C4 cleavage assays in rat and mouse\",\n      \"pmids\": [\"10586086\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve the C2 cleavage step or convertase assembly\", \"Hepatic restriction inferred from tissue expression, not lineage tracing\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Defined the binding partitioning that gives the lectin pathway its specificity: MASP-2/MAp19 associate exclusively with MBL while C1r/C1s associate with C1q.\",\n      \"evidence\": \"Gel-permeation chromatography, C1r-deficient serum depletion, and complement activation assays\",\n      \"pmids\": [\"10878362\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Most serum MASPs were not MBL-bound, leaving the function of free MASP pools unexplained\", \"Ficolin partners not yet examined\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Mapped MASP2 to chromosome 1p36 and established its evolutionary origin shared with C1s via exon shuffling, explaining the proteases' similar architecture and substrate specificity.\",\n      \"evidence\": \"Genomic sequencing and comparative gene structure analysis with C1s\",\n      \"pmids\": [\"11426320\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Evolutionary inference, not functional\", \"Did not address what distinguishes MASP-2 catalytic behavior from C1s\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Provided the structural and enzymatic basis for MASP-2 catalysis, showing the CCP2 module stabilizes the SP domain, defining modular flexibility, and revealing that MASP-2 is best assayed on its natural substrate C4 because it barely cleaves small peptides.\",\n      \"evidence\": \"X-ray crystallography of the catalytic fragment, differential scanning calorimetry, and fluorescent substrate/inhibitor profiling\",\n      \"pmids\": [\"15364579\", \"14725788\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full-length zymogen and complex architecture not resolved\", \"Mechanism of substrate recognition by surface loops only partly defined\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Solved the structure of the MAp19 splice product and mapped the CUB1 residues mediating Ca2+-dependent binding to MBL and L-ficolin, defining the shared docking site for pattern-recognition molecules.\",\n      \"evidence\": \"X-ray crystallography and SPR with point mutants\",\n      \"pmids\": [\"15117939\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Binding site mapped on MAp19; full MASP-2/MBL complex geometry not determined\", \"Physiological role of MAp19 binding left open\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Dissected the structural determinants of MASP-2 substrate efficiency, attributing superior C4 cleavage to the CCP modules and C2 cleavage efficiency to the SP domain.\",\n      \"evidence\": \"C1s/MASP-2 chimera mutagenesis with quantitative kinetic characterization\",\n      \"pmids\": [\"16227207\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which CCP modules enhance C4 docking not structurally visualized\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Extended the partner repertoire by showing MASP-2 forms complement-active complexes with ficolin A, with sMAP/MAp19 acting as a competitive inhibitor.\",\n      \"evidence\": \"Recombinant reconstitution, co-immunoprecipitation, and complement activation assays in mouse\",\n      \"pmids\": [\"16328467\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"sMAP competition later contested under physiological conditions\", \"Single lab, mouse system\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Resolved the ordered convertase assembly mechanism: C2 binds nascent C4b rather than native C4, and C4b remains bound to MASP-2, localizing C4b deposition near the activating complex.\",\n      \"evidence\": \"SPR binding kinetics and enzymatic cleavage analysis of MASP-2, C4, C2 and fragments\",\n      \"pmids\": [\"17204478\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Surface-bound convertase geometry on real pathogens not directly observed\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Defined MASP-2 cleavage specificity by subsite, established it as up to 1000-fold more active than C1s on peptides, and identified C1-inhibitor as its principal physiological serpin.\",\n      \"evidence\": \"Phage display substrate library, peptide cleavage assays, and serpin inhibition kinetics\",\n      \"pmids\": [\"17709141\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Specificity determined on peptides; relevance to additional natural substrates beyond C4/C2 not addressed\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Established that both MASP-1 and MASP-2 are individually essential for lectin-pathway activation and that MASP-1 transactivates MASP-2 zymogen, with high-resolution Michaelis complexes revealing protease plasticity.\",\n      \"evidence\": \"Directed-evolution monospecific inhibitors, complement activation assays, and 1.28 A crystallography\",\n      \"pmids\": [\"22511776\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinetics of transactivation in the assembled complex not fully quantified\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Showed that MASP-1 and MASP-2 are co-assembled within a single MBL/ficolin complex (not direct heterodimers) to enable transactivation, and that MAp44 inhibits by disrupting these co-complexes.\",\n      \"evidence\": \"Co-immunoprecipitation, functional complement assays, and serum complex characterization\",\n      \"pmids\": [\"23785123\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and spatial arrangement within native complexes not structurally resolved\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Quantified serum MAp19 and MASP-2 and overturned the model of MAp19 as a physiological competitive inhibitor of MASP-2, showing MAp19 does not displace MASP-2 from MBL under physiological conditions.\",\n      \"evidence\": \"Quantitative ELISA, serum fractionation, complement inhibition assays, and IHC/qRT-PCR\",\n      \"pmids\": [\"21871896\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological function of abundant free/urinary MAp19 remains unexplained\", \"Conflicts with earlier mouse ficolin A data\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Identified TFPI as a selective endogenous inhibitor of MASP-2 acting through its Kunitz-2 domain, expanding regulators beyond C1-inhibitor.\",\n      \"evidence\": \"Ex vivo C4 deposition and fluid-phase chromogenic assays with domain-specific blocking antibodies\",\n      \"pmids\": [\"25359215\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Physiological significance of TFPI-mediated MASP-2 regulation in vivo not established\", \"Single lab\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Distinguished MASP function in factor D maturation, showing MASP-2 (and MASP-1) do not activate pro-factor D in plasma, isolating that role to MASP-3.\",\n      \"evidence\": \"Selective MASP inhibitors and recombinant MASP addition in plasma with kinetic pro-FD assays\",\n      \"pmids\": [\"26673137\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Defines what MASP-2 does not do; no new MASP-2 substrate identified\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Demonstrated a pathogenic role for MASP-2 in post-ischemic brain injury, with genetic and antibody-based loss of MASP-2 (but not MASP-1/3) conferring protection.\",\n      \"evidence\": \"MASP-2-/-, MASP-1/3-/-, fB-/- mice in MCAO models plus antibody blockade and IHC readouts\",\n      \"pmids\": [\"27577570\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Lectin- versus alternative-pathway amplification contributions not fully separated\", \"Human relevance inferred from mouse\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Linked MASP2 loss-of-function variants to herpes simplex encephalitis, showing G634R abolishes secretion and zymogen maturation and implicating the MBL/MASP-2 pathway in antiviral defense.\",\n      \"evidence\": \"In vitro variant expression and autoactivation assays plus MBL-deficient murine HSE model\",\n      \"pmids\": [\"31869396\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal chain from MASP-2 deficiency to human HSE not proven beyond association\", \"Murine model used MBL deficiency as surrogate\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Established MASP-2 as a direct mediator of endothelial injury in thrombotic microangiopathy, with anti-MASP2 antibody suppressing patient-plasma-induced endothelial caspase-8 activation.\",\n      \"evidence\": \"Patient-plasma MVEC caspase-8 activation assay +/- narsoplimab and plasma complement ELISA\",\n      \"pmids\": [\"32681658\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vitro endothelial readout; in vivo TMA causation not established\", \"Single lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Proposed a direct MASP-2/coronavirus nucleocapsid interaction driving aberrant complement activation in viral lung injury.\",\n      \"evidence\": \"In silico screening with complement assays, citing prior antibody-blocking experiments\",\n      \"pmids\": [\"33671334\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Primarily computational; mechanistic interaction rests on prior cited literature not new experiments\", \"Direct binding not independently confirmed here\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Extended MASP-2's pathogenic role to sickle cell disease, showing antibody inhibition reduces complement deposition, inflammation, and microvascular vaso-occlusion.\",\n      \"evidence\": \"Inhibitory anti-MASP-2 antibody in Townes SS mice with complement markers, IHC, and intravital microscopy\",\n      \"pmids\": [\"35878790\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab; relative contributions of lectin versus alternative pathway not fully dissected\", \"Human therapeutic translation not addressed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The physiological function of the abundant free and urinary MAp19 pool and the in vivo relevance of non-canonical MASP-2 regulators (TFPI) and disease interactions remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No function assigned to non-MBL-bound MAp19\", \"In vivo significance of TFPI-mediated MASP-2 inhibition unknown\", \"Whether MASP-2 has substrates beyond C4/C2 not established\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 6, 7, 10]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 2, 7]},\n      {\"term_id\": \"GO:0008236\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [4, 12, 14]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [0, 5, 8]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [6, 10]}\n    ],\n    \"complexes\": [\n      \"MBL-MASP complex\",\n      \"ficolin-MASP complex\"\n    ],\n    \"partners\": [\n      \"MBL2\",\n      \"FCN2\",\n      \"FCN1\",\n      \"FCN3\",\n      \"MASP1\",\n      \"C4\",\n      \"C2\",\n      \"SERPING1\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}