{"gene":"LMAN2","run_date":"2026-06-10T02:59:50","timeline":{"discoveries":[{"year":1994,"finding":"VIP36 (LMAN2) was purified from CHAPS-insoluble (glycolipid raft) fractions of MDCK cells and its cDNA was isolated; the N-terminal 31 kDa luminal domain shows homology to leguminous plant lectins. Transiently expressed VIP36 localizes to the Golgi apparatus, endosomal/vesicular structures, and the plasma membrane, consistent with a role in Golgi-to-cell-surface transport.","method":"Biochemical purification, cDNA cloning, immunofluorescence/subcellular localization of transiently expressed protein","journal":"The EMBO journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — original isolation and localization by multiple methods (purification, cDNA, imaging) in a single foundational study","pmids":["8157011"],"is_preprint":false},{"year":1996,"finding":"The recombinant luminal/exoplasmic domain of VIP36 binds Ca2+ and can decorate internal membrane structures of MDCK cells in vitro; this binding requires Ca2+ and is specifically inhibited by N-acetyl-D-galactosamine. Glycopeptides from galactose-labeled cells bind to VIP36 and can be eluted with N-acetyl-D-galactosamine, demonstrating lectin activity.","method":"Recombinant protein production, Ca2+ binding assay, in vitro membrane-binding assay, affinity chromatography with competitive inhibition","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro binding assay with specific inhibition, single lab, multiple orthogonal approaches","pmids":["8834812"],"is_preprint":false},{"year":1999,"finding":"Endogenous VIP36 localizes to the Golgi apparatus and the early secretory pathway (ER-Golgi intermediate compartment) of MDCK and Vero cells; it co-localizes with coatomer and ERGIC-53 and cycles in the early secretory pathway as shown by brefeldin A treatment and co-localization with anterograde cargo.","method":"High-resolution confocal microscopy, brefeldin A treatment, co-localization with marker proteins (endogenous protein)","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization of endogenous protein using multiple approaches in a single focused study","pmids":["10444376"],"is_preprint":false},{"year":1999,"finding":"VIP36 specifically recognizes high-mannose type glycans containing alpha1→2 mannosyl residues (Man7-9GlcNAc2) in a pH-optimum of 6.0; the interaction is Ca2+-independent and has an association constant of ~2.1×10^8 M^-1 with thyroglobulin glycans as measured by surface plasmon resonance.","method":"GST-fusion protein binding assay, inhibition studies with specific glycans, surface plasmon resonance biosensor","journal":"Glycobiology","confidence":"High","confidence_rationale":"Tier 1 / Strong — quantitative in vitro binding assay with defined ligands and SPR measurement, replicated in subsequent studies","pmids":["10406849"],"is_preprint":false},{"year":2002,"finding":"VIP36 is localized to the apical membrane of polarized MDCK cells (apical/basolateral ratio ~2); overexpression of wild-type VIP36 increased apical transport and secretion of VIP36-recognized (high-mannose) glycoproteins (including clusterin), while a lectin-inactive mutant had no effect on glycoprotein distribution and inhibited secretion, demonstrating that VIP36 lectin activity is required for apical glycoprotein transport.","method":"VIP36 overexpression and lectin-dead mutant expression in polarized MDCK cells, measurement of apical/basolateral distribution and secretion rates","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional mutagenesis in polarized cells with defined cargo readout, single lab","pmids":["11872745"],"is_preprint":false},{"year":2003,"finding":"Endogenous VIP36 localizes to the trans-Golgi network, immature secretory granules, and mature secretory granules in rat parotid acinar cells, co-localizing with alpha-amylase in apical regions, indicating a post-Golgi secretory pathway role.","method":"Immunoelectron microscopy and double-staining immunofluorescence of rat parotid gland tissue (endogenous protein)","journal":"The journal of histochemistry and cytochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization of endogenous protein by immunoelectron microscopy in relevant tissue","pmids":["12871987"],"is_preprint":false},{"year":2004,"finding":"VIP36 physically associates with alpha-amylase in parotid secretory vesicles via high-mannose type glycans; co-precipitation of alpha-amylase with VIP36 was abolished by endo H treatment (removing high-mannose glycans), and alpha-amylase in secretory vesicles carries high-mannose glycans.","method":"Subcellular fractionation (Percoll gradient), immunoelectron microscopy, co-immunoprecipitation with endo H treatment","journal":"Glycobiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP with enzymatic validation (endo H), co-localization, single lab","pmids":["15070860"],"is_preprint":false},{"year":2005,"finding":"The carbohydrate recognition domain (CRD) of VIP36 selectively binds the deglucosylated trimannose of the D1 branch of high-mannose oligosaccharides with bell-shaped pH dependence (optimum ~6.5), consistent with binding in the cis-Golgi and releasing cargo in the ER (higher pH), suggesting a role in glycoprotein quality control.","method":"Frontal affinity chromatography (FAC) with pyridylaminated sugar library (21 oligosaccharides), recombinant CRD","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — quantitative FAC with defined panel of isomeric oligosaccharides, replicated in subsequent studies","pmids":["16129679"],"is_preprint":false},{"year":2007,"finding":"Crystal structures of VIP36 luminal domain (CRD + stalk) in apo, Ca2+-bound, and mannosyl ligand-bound forms reveal a 17-stranded antiparallel beta-sandwich CRD; Ca2+ coordinates Asp131, Asn166, and His190 to enable carbohydrate binding; Man-α1,2-Man-α1,2-Man (D1 arm) is recognized by eight residues via extensive hydrogen bonds, explaining Ca2+-dependent and D1-arm-specific high-mannose glycoprotein recognition.","method":"X-ray crystallography of apo, Ca2+, and ligand-bound forms; structure-guided interpretation of substrate specificity","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structures of multiple states with defined active-site residues, provides mechanistic basis replicated by other structural studies","pmids":["17652092"],"is_preprint":false},{"year":2007,"finding":"Frontal affinity chromatography comparing ERGIC-53, VIPL, and VIP36 CRDs showed that VIPL and VIP36 selectively bind deglucosylated trimannose of the D1 branch but with different pH dependence, while ERGIC-53 binds high-mannose oligosaccharides broadly. Structure-based mutagenesis showed that sugar-binding properties of these lectins can be switched by single amino acid substitutions.","method":"Frontal affinity chromatography with pyridylaminated sugar library; structure-based site-directed mutagenesis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — quantitative FAC combined with mutagenesis confirming structural determinants of sugar specificity","pmids":["18025080"],"is_preprint":false},{"year":2007,"finding":"VIP36 stably interacts with the ER chaperone BiP in an ATP-independent and carbohydrate-independent manner dependent on divalent cations; the interaction occurs in the ER (confirmed by immunoelectron microscopy) and is distinct from canonical chaperone-substrate interactions, suggesting a novel role for VIP36 in quality control of secretory proteins.","method":"Chemical crosslinking, co-immunoprecipitation, LC/MS/MS identification, immunoelectron microscopy, surface plasmon resonance with recombinant proteins; lectin-dead mutant used as control","journal":"Glycobiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus SPR with recombinant proteins, two orthogonal methods, single lab","pmids":["17586539"],"is_preprint":false},{"year":2010,"finding":"VIP36 interacts with alpha1-antitrypsin (alpha1-AT) specifically via its high-mannose glycans in Golgi and ER compartments (not the complex glycoform); silencing VIP36 accelerated alpha1-AT transport, arguing against an anterograde role and consistent with a post-ER quality control function where VIP36 recycles alpha1-AT from Golgi back to ER.","method":"YFP fragment complementation (bimolecular fluorescence complementation) screen of human liver cDNA library, mutagenesis of glycosylation sites, kifunensine treatment, VIP36 siRNA knockdown with transport kinetics","journal":"Traffic (Copenhagen, Denmark)","confidence":"High","confidence_rationale":"Tier 2 / Strong — unbiased screen followed by multiple orthogonal validations (BiFC, glycosylation mutants, pharmacological intervention, siRNA) in a single rigorous study","pmids":["20477988"],"is_preprint":false},{"year":2011,"finding":"VIP36 is a target of ectodomain shedding on the cell surface (not in the Golgi/ER) in macrophages; the amount of VIP36 at the cell surface precisely regulates phagocytosis, and shedding of VIP36 is required for this regulation of phagocytic activity.","method":"Unbiased proteomic screening (LPS-stimulated macrophage conditioned media), cell surface shedding assay, VIP36 manipulation (overexpression/knockdown) with phagocytosis readout","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — proteomic identification with functional gain/loss-of-function experiment, single lab","pmids":["22016386"],"is_preprint":false},{"year":2012,"finding":"VIP36 interacts with the receptor guanylyl cyclase GC-C; this interaction depends on glycosylation at specific sites that also allow GC-C to fold properly and bind ligand, identifying GC-C as the first receptor client of VIP36.","method":"Co-immunoprecipitation, mutagenesis of 10 glycosylation sites in GC-C, pharmacological inhibition of glycosylation","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP with systematic mutagenesis linking VIP36 binding to specific glycosylation sites, single lab","pmids":["23269669"],"is_preprint":false},{"year":2014,"finding":"Crystal structure of ERGIC-53 CRD in complex with MCFD2 and α1,2-mannotriose revealed a shallower sugar-binding pocket in ERGIC-53 compared to VIP36 due to a single Asp-to-Gly substitution; this structural difference explains the broader sugar specificity of ERGIC-53 versus the D1-arm-specific binding of VIP36.","method":"X-ray crystallography of ERGIC-53 CRD/MCFD2/mannotriose complex; structural comparison with VIP36","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 1 / Moderate — crystal structure with direct structural comparison identifying single amino acid determinant of specificity differences","pmids":["24498414"],"is_preprint":false},{"year":2016,"finding":"LMAN2 (VIP36) is specifically required for the accumulation of the exosome cargo protein GPRC5B in the Golgi complex and restricts its transport along the exosomal pathway; LMAN2 may interfere with GGA1-mediated trans-Golgi network-to-endosome transport of GPRC5B.","method":"Inducible expression system for GPRC5B, LMAN2 knockdown, trafficking assay, co-localization, analysis of GGA1-mediated transport","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — defined cargo with loss-of-function and pathway placement (GGA1), single lab","pmids":["27765817"],"is_preprint":false},{"year":2024,"finding":"LMAN2 co-expression with Kv1.2 causes a large depolarizing shift in channel activation voltage and deceleration of activation kinetics; shRNA knockdown of endogenous LMAN2 reduces Kv1.2 redox sensitivity and gating variability. Kv1.2 sensitivity to LMAN2 requires residues F251 and T252 in the intracellular S2-S3 linker, which also mediate redox-dependent gating, suggesting LMAN2 acts through the same pathway as extracellular redox modulation.","method":"Patch-clamp electrophysiology in CHO and L(tk-) cell lines, shRNA knockdown of endogenous LMAN2, Kv1.2 point mutations (F251, T252), functional screening of 52 candidate genes","journal":"Function (Oxford, England)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional gain and loss-of-function with mutagenesis identifying specific channel residues, single lab, multiple cell lines","pmids":["39264045"],"is_preprint":false},{"year":2024,"finding":"LMAN2 and the amino acid transporter Slc7a5 competitively modulate Kv1.2 gating in opposite directions; co-expression of both produces bimodal voltage-dependence suggesting two non-overlapping channel populations. Using Kv1.2:1.5 chimeras, distinct regions in S1-S3 of the voltage-sensing domain are required for LMAN2 versus Slc7a5 sensitivity, confirming that the two regulators compete for interaction with the Kv1.2 voltage sensor.","method":"Patch-clamp electrophysiology, Kv1.2:Kv1.5 chimeric channel approach, co-expression of LMAN2 and Slc7a5","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — chimeric channel approach identifies specific VSD segments, functional competition assay, single lab","pmids":["39659243"],"is_preprint":false},{"year":2024,"finding":"VIP36 (LMAN2) is susceptible to ectodomain shedding followed by gamma-secretase-mediated intramembrane proteolysis (regulated intramembrane proteolysis, RIP); the C-terminal amino acids of its transmembrane domain regulate gamma-secretase susceptibility, as shown by substitution mutant analysis. VIPL, the close homolog, has different gamma-secretase susceptibility despite similar shedding.","method":"Substitution mutagenesis of transmembrane domain C-terminal residues, gamma-secretase processing assay, comparison with VIPL mutants","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mutagenesis identifying specific TMD residues controlling intramembrane proteolysis, single lab","pmids":["38219489"],"is_preprint":false},{"year":2024,"finding":"LMAN2 physically interacts with MAPK9 (JNK2) in breast cancer cells and activates the MAPK signaling pathway, promoting cisplatin resistance; knockdown of LMAN2 reduced MAPK pathway activation and sensitized drug-resistant cells to cisplatin in vivo.","method":"Co-immunoprecipitation, immunofluorescence co-localization, siRNA knockdown, tumor xenograft model","journal":"Cancer medicine","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP identifying interaction with MAPK9, pathway activation inferred from downstream markers, single lab","pmids":["39618331"],"is_preprint":false}],"current_model":"LMAN2 (VIP36) is a type I transmembrane L-type lectin of the early secretory pathway that cycles between the ER and cis/medial-Golgi; its luminal carbohydrate recognition domain (17-stranded beta-sandwich) binds high-mannose N-glycans carrying the intact α1,2-linked D1 mannosyl arm in a Ca²⁺-dependent manner with pH optimum ~6.5, enabling it to capture glycoprotein cargo (e.g., alpha1-antitrypsin, GC-C, alpha-amylase) in the Golgi and recycle them to the ER for post-ER quality control; at the cell surface it undergoes ADAM-mediated ectodomain shedding (regulated by C-terminal transmembrane residues for subsequent gamma-secretase processing) that controls macrophage phagocytosis; LMAN2 also facilitates apical sorting of high-mannose glycoproteins in polarized epithelial cells, restricts exosome cargo (GPRC5B) exit from the Golgi via interference with GGA1-mediated transport, and acts as a regulatory auxiliary protein for Kv1.2 potassium channels by shifting their voltage-dependence toward depolarized potentials through interaction with the S2-S3 intracellular linker, competing with the Slc7a5 transporter for the channel voltage-sensing domain."},"narrative":{"mechanistic_narrative":"LMAN2 (VIP36) is a type I transmembrane L-type lectin of the early secretory pathway that recognizes high-mannose N-glycans and recycles glycoprotein cargo between the Golgi and the ER as part of post-ER quality control [PMID:8157011, PMID:10406849, PMID:20477988]. Its luminal carbohydrate recognition domain is a 17-stranded antiparallel beta-sandwich that coordinates Ca²⁺ through Asp131, Asn166, and His190 and engages the α1,2-linked D1 trimannose arm of Man7-9GlcNAc2 oligosaccharides through extensive hydrogen bonding by eight residues [PMID:17652092]. Binding is D1-arm-specific with a bell-shaped pH optimum near 6.5, a property that favors cargo capture in the acidic cis-Golgi and release at the higher pH of the ER; a single amino acid difference distinguishes this narrow specificity from the broader high-mannose binding of the related lectin ERGIC-53 [PMID:16129679, PMID:18025080, PMID:24498414]. Through this glycan-dependent recognition LMAN2 captures clients including alpha1-antitrypsin, the receptor guanylyl cyclase GC-C, and alpha-amylase, and silencing LMAN2 accelerates alpha1-antitrypsin transport, consistent with a retrograde Golgi-to-ER recycling role rather than an anterograde one [PMID:15070860, PMID:20477988, PMID:23269669]. The lectin also localizes apically in polarized epithelial cells where its carbohydrate activity is required for apical transport and secretion of high-mannose glycoproteins, and it restricts exosome cargo GPRC5B exit from the Golgi by interfering with GGA1-mediated transport [PMID:11872745, PMID:27765817]. Beyond the secretory pathway, LMAN2 reaches the cell surface where it undergoes ADAM-type ectodomain shedding followed by gamma-secretase-mediated intramembrane proteolysis governed by C-terminal transmembrane residues, with surface levels controlling macrophage phagocytosis [PMID:22016386, PMID:38219489]. LMAN2 additionally functions as an auxiliary regulator of Kv1.2 potassium channels, producing a depolarizing shift in activation voltage through the intracellular S2-S3 linker (residues F251/T252) and competing with the Slc7a5 transporter for the channel voltage-sensing domain [PMID:39264045, PMID:39659243].","teleology":[{"year":1994,"claim":"Establishing the existence and trafficking itinerary of VIP36 was the first step, framing it as a membrane protein of the Golgi-to-cell-surface route with lectin homology.","evidence":"Biochemical purification from MDCK raft fractions, cDNA cloning, and imaging of transiently expressed protein","pmids":["8157011"],"confidence":"Medium","gaps":["Overexpression localization may not reflect endogenous steady state","No glycan ligand defined","No functional cargo identified"]},{"year":1996,"claim":"Demonstrating Ca²⁺-dependent, sugar-competable binding confirmed VIP36 is a functional lectin rather than merely a lectin-homologous protein.","evidence":"Recombinant luminal domain Ca²⁺ and membrane-binding assays with GalNAc inhibition and glycopeptide affinity chromatography","pmids":["8834812"],"confidence":"Medium","gaps":["GalNAc-based specificity later revised toward high-mannose glycans","Physiological ligand not yet defined","No structural basis for binding"]},{"year":1999,"claim":"Localizing the endogenous protein to the ERGIC and defining its high-mannose D1-arm specificity established VIP36 as a recycling early-secretory-pathway lectin with a pH-tuned binding profile.","evidence":"Confocal microscopy with brefeldin A and ERGIC-53/coatomer co-localization; SPR and inhibition with defined glycans","pmids":["10444376","10406849"],"confidence":"High","gaps":["Direction of cargo flow (anterograde vs retrograde) not resolved","Endogenous cargo not identified","Ca²⁺ dependence reported inconsistently between binding studies"]},{"year":2002,"claim":"Functional mutagenesis showed lectin activity is required for apical glycoprotein transport, assigning VIP36 a sorting role in polarized cells.","evidence":"Wild-type and lectin-dead VIP36 expression in polarized MDCK cells with apical/basolateral cargo distribution and secretion readouts","pmids":["11872745"],"confidence":"Medium","gaps":["Mechanism of apical sorting not defined","Generality beyond MDCK unclear","Conflicts with later retrograde quality-control model"]},{"year":2003,"claim":"Tissue localization to secretory granules of parotid acinar cells, and glycan-dependent co-precipitation with alpha-amylase, identified a physiological client engaged through high-mannose glycans.","evidence":"Immunoelectron microscopy of rat parotid gland and co-IP with endo H sensitivity","pmids":["12871987","15070860"],"confidence":"Medium","gaps":["Functional consequence for amylase secretion not tested","Single tissue system","Direct vs indirect association not fully separated"]},{"year":2005,"claim":"Defining the bell-shaped pH dependence of D1-trimannose binding provided a physical model for cargo capture in the cis-Golgi and release in the ER, framing a quality-control cycle.","evidence":"Frontal affinity chromatography of recombinant CRD against a pyridylaminated oligosaccharide library","pmids":["16129679"],"confidence":"High","gaps":["Direct demonstration of pH-driven cargo release in cells not shown","Cargo set still limited"]},{"year":2007,"claim":"Crystal structures and comparative FAC/mutagenesis defined the atomic basis of Ca²⁺-dependent D1-arm recognition and showed how single residues tune specificity across the VIP36/VIPL/ERGIC-53 lectin family.","evidence":"X-ray structures of apo, Ca²⁺-bound, and ligand-bound luminal domain; FAC with structure-guided point mutagenesis","pmids":["17652092","18025080"],"confidence":"High","gaps":["Structures do not capture cargo glycoprotein engagement","pH-dependent conformational switch not visualized"]},{"year":2007,"claim":"Identifying a stable, carbohydrate-independent interaction with the ER chaperone BiP linked VIP36 to a non-canonical quality-control function beyond its lectin activity.","evidence":"Crosslinking, reciprocal co-IP with LC/MS/MS, immunoelectron microscopy, and SPR with lectin-dead control","pmids":["17586539"],"confidence":"Medium","gaps":["Functional consequence of BiP binding not established","Stoichiometry and cellular context unclear","Single lab"]},{"year":2010,"claim":"Identifying alpha1-antitrypsin as a glycan-dependent client and showing that knockdown accelerates its transport resolved the trafficking direction, establishing VIP36 as a post-ER retrograde quality-control receptor.","evidence":"BiFC screen of human liver cDNA, glycosylation-site mutants, kifunensine treatment, and siRNA transport kinetics","pmids":["20477988"],"confidence":"High","gaps":["Quantitative contribution to ER retention not measured","Reconciliation with apical anterograde role incomplete"]},{"year":2012,"claim":"Discovery of cell-surface ectodomain shedding controlling macrophage phagocytosis revealed a functional role for VIP36 outside the secretory pathway.","evidence":"Proteomic screen of macrophage conditioned media with surface shedding assay and gain/loss-of-function phagocytosis readout","pmids":["22016386"],"confidence":"Medium","gaps":["Sheddase identity not pinned down here","Mechanism linking surface levels to phagocytosis unclear","Single lab"]},{"year":2012,"claim":"Identifying the receptor guanylyl cyclase GC-C as a glycosylation-dependent client extended the client repertoire to a signaling receptor whose folding correlates with VIP36 binding.","evidence":"Co-IP with systematic mutagenesis of ten GC-C glycosylation sites and glycosylation inhibition","pmids":["23269669"],"confidence":"Medium","gaps":["Direct vs glycan-bridged interaction not fully separated","Effect on GC-C trafficking not quantified"]},{"year":2014,"claim":"Structural comparison of the ERGIC-53/MCFD2 complex with VIP36 pinpointed a single Asp-to-Gly substitution as the determinant of their divergent glycan specificities.","evidence":"X-ray crystallography of ERGIC-53 CRD/MCFD2/mannotriose complex with structural comparison","pmids":["24498414"],"confidence":"High","gaps":["No bound MCFD2-equivalent partner for VIP36 identified","Functional consequence of pocket depth in cells not tested"]},{"year":2016,"claim":"Showing that LMAN2 retains GPRC5B in the Golgi and restricts its exosomal exit via GGA1 placed the lectin in a pathway controlling cargo partitioning into the exosomal route.","evidence":"Inducible GPRC5B expression, LMAN2 knockdown, trafficking and co-localization assays with GGA1 analysis","pmids":["27765817"],"confidence":"Medium","gaps":["Direct LMAN2-GPRC5B interaction not defined","Mechanism of GGA1 interference unclear","Single lab"]},{"year":2024,"claim":"Electrophysiology defined a previously unknown role for LMAN2 as a Kv1.2 auxiliary regulator, shifting activation voltage through the S2-S3 linker and competing with Slc7a5 at the voltage-sensing domain.","evidence":"Patch-clamp in CHO and L(tk-) cells, shRNA knockdown, Kv1.2 point mutations (F251/T252) and Kv1.2:1.5 chimeras with Slc7a5 co-expression","pmids":["39264045","39659243"],"confidence":"Medium","gaps":["Whether regulation requires lectin activity unknown","Physiological setting and stoichiometry undefined","Single lab"]},{"year":2024,"claim":"Mapping gamma-secretase-mediated intramembrane proteolysis to specific C-terminal transmembrane residues extended the surface-shedding pathway into regulated intramembrane proteolysis.","evidence":"Substitution mutagenesis of TMD C-terminal residues with gamma-secretase processing assay and VIPL comparison","pmids":["38219489"],"confidence":"Medium","gaps":["Fate and function of released intracellular fragment unknown","Physiological trigger for RIP unclear"]},{"year":2024,"claim":"A reported interaction with MAPK9 (JNK2) tied LMAN2 to MAPK-driven cisplatin resistance in breast cancer, an emerging disease-context role.","evidence":"Co-IP, co-localization, siRNA knockdown and xenograft cisplatin sensitivity","pmids":["39618331"],"confidence":"Low","gaps":["Single Co-IP without reciprocal validation","Pathway activation inferred from downstream markers only","Direct vs indirect interaction unresolved"]},{"year":null,"claim":"It remains unresolved how LMAN2's glycan-recognition activity mechanistically relates to its non-lectin functions at the cell surface (shedding/RIP, phagocytosis) and at ion channels (Kv1.2 regulation).","evidence":"","pmids":[],"confidence":"Low","gaps":["Whether channel regulation and surface functions require the CRD is untested","No integrated model linking secretory and plasma-membrane roles","Native interactomes for non-glycan partners not mapped"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0038024","term_label":"cargo receptor activity","supporting_discovery_ids":[11,13]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[16,17]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[0,2,5,15]},{"term_id":"GO:0005783","term_label":"endoplasmic reticulum","supporting_discovery_ids":[2,10,11]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,12,18]}],"pathway":[{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[4,11,15]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[11,15]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[11,13]}],"complexes":[],"partners":["HSPA5","SERPINA1","GUCY2C","AMY1","GPRC5B","KCNA2","SLC7A5","MAPK9"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q12907","full_name":"Vesicular integral-membrane protein VIP36","aliases":["Glycoprotein GP36b","Lectin mannose-binding 2","Vesicular integral-membrane protein 36","VIP36"],"length_aa":356,"mass_kda":40.2,"function":"Plays a role as an intracellular lectin in the early secretory pathway. Interacts with N-acetyl-D-galactosamine and high-mannose type glycans and may also bind to O-linked glycans. Involved in the transport and sorting of glycoproteins carrying high mannose-type glycans (By similarity)","subcellular_location":"Endoplasmic reticulum-Golgi intermediate compartment membrane; Golgi apparatus membrane; Endoplasmic reticulum membrane","url":"https://www.uniprot.org/uniprotkb/Q12907/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/LMAN2","classification":"Not Classified","n_dependent_lines":11,"n_total_lines":1208,"dependency_fraction":0.009105960264900662},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"ARF4","stoichiometry":10.0},{"gene":"YIPF5","stoichiometry":10.0},{"gene":"RER1","stoichiometry":4.0},{"gene":"SEC61B","stoichiometry":4.0},{"gene":"TMED2","stoichiometry":4.0},{"gene":"CALD1","stoichiometry":0.2},{"gene":"CANX","stoichiometry":0.2},{"gene":"GORASP2","stoichiometry":0.2},{"gene":"RAB1A","stoichiometry":0.2},{"gene":"SCYL1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/LMAN2","total_profiled":1310},"omim":[{"mim_id":"616887","title":"INTELLECTUAL DEVELOPMENTAL DISORDER, AUTOSOMAL RECESSIVE 52; MRT52","url":"https://www.omim.org/entry/616887"},{"mim_id":"609552","title":"LECTIN, MANNOSE-BINDING 2-LIKE; LMAN2L","url":"https://www.omim.org/entry/609552"},{"mim_id":"609551","title":"LECTIN, MANNOSE-BINDING 2; LMAN2","url":"https://www.omim.org/entry/609551"},{"mim_id":"601567","title":"LECTIN, MANNOSE-BINDING 1; LMAN1","url":"https://www.omim.org/entry/601567"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Golgi apparatus","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/LMAN2"},"hgnc":{"alias_symbol":["GP36B","VIP36"],"prev_symbol":["C5orf8"]},"alphafold":{"accession":"Q12907","domains":[{"cath_id":"2.60.120.200","chopping":"54-290","consensus_level":"high","plddt":95.2561,"start":54,"end":290}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q12907","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q12907-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q12907-F1-predicted_aligned_error_v6.png","plddt_mean":84.06},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=LMAN2","jax_strain_url":"https://www.jax.org/strain/search?query=LMAN2"},"sequence":{"accession":"Q12907","fasta_url":"https://rest.uniprot.org/uniprotkb/Q12907.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q12907/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q12907"}},"corpus_meta":[{"pmid":"8157011","id":"PMC_8157011","title":"VIP36, a novel component of glycolipid rafts and exocytic carrier vesicles in epithelial cells.","date":"1994","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/8157011","citation_count":200,"is_preprint":false},{"pmid":"18025080","id":"PMC_18025080","title":"Molecular basis of sugar recognition by the human L-type lectins ERGIC-53, VIPL, and VIP36.","date":"2007","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/18025080","citation_count":121,"is_preprint":false},{"pmid":"10444376","id":"PMC_10444376","title":"VIP36 localisation to the early secretory pathway.","date":"1999","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/10444376","citation_count":91,"is_preprint":false},{"pmid":"11872745","id":"PMC_11872745","title":"Involvement of VIP36 in intracellular transport and secretion of glycoproteins in polarized Madin-Darby canine kidney (MDCK) cells.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/11872745","citation_count":80,"is_preprint":false},{"pmid":"8834812","id":"PMC_8834812","title":"Characterization of VIP36, an animal lectin homologous to leguminous lectins.","date":"1996","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/8834812","citation_count":75,"is_preprint":false},{"pmid":"16129679","id":"PMC_16129679","title":"Sugar-binding properties of VIP36, an intracellular animal lectin operating as a cargo receptor.","date":"2005","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16129679","citation_count":71,"is_preprint":false},{"pmid":"10406849","id":"PMC_10406849","title":"Vesicular-integral membrane protein, VIP36, recognizes high-mannose type glycans containing alpha1-->2 mannosyl residues in MDCK cells.","date":"1999","source":"Glycobiology","url":"https://pubmed.ncbi.nlm.nih.gov/10406849","citation_count":61,"is_preprint":false},{"pmid":"12609988","id":"PMC_12609988","title":"Profile-based data base scanning for animal L-type lectins and characterization of VIPL, a novel VIP36-like endoplasmic reticulum protein.","date":"2003","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12609988","citation_count":59,"is_preprint":false},{"pmid":"12878160","id":"PMC_12878160","title":"VIPL, a VIP36-like membrane protein with a putative function in the export of glycoproteins from the endoplasmic reticulum.","date":"2003","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/12878160","citation_count":50,"is_preprint":false},{"pmid":"27765817","id":"PMC_27765817","title":"Adaptor Protein CD2AP and L-type Lectin LMAN2 Regulate Exosome Cargo Protein Trafficking through the Golgi Complex.","date":"2016","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/27765817","citation_count":46,"is_preprint":false},{"pmid":"17652092","id":"PMC_17652092","title":"Structural basis for recognition of high mannose type glycoproteins by mammalian transport lectin VIP36.","date":"2007","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/17652092","citation_count":42,"is_preprint":false},{"pmid":"31535203","id":"PMC_31535203","title":"White matter DNA methylation profiling reveals deregulation of HIP1, LMAN2, MOBP, and other loci in multiple system atrophy.","date":"2019","source":"Acta neuropathologica","url":"https://pubmed.ncbi.nlm.nih.gov/31535203","citation_count":39,"is_preprint":false},{"pmid":"22016386","id":"PMC_22016386","title":"VIP36 protein is a target of ectodomain shedding and regulates phagocytosis in macrophage Raw 264.7 cells.","date":"2011","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/22016386","citation_count":37,"is_preprint":false},{"pmid":"20477988","id":"PMC_20477988","title":"Role of the lectin VIP36 in post-ER quality control of human alpha1-antitrypsin.","date":"2010","source":"Traffic (Copenhagen, Denmark)","url":"https://pubmed.ncbi.nlm.nih.gov/20477988","citation_count":34,"is_preprint":false},{"pmid":"17169971","id":"PMC_17169971","title":"Detection of weak sugar binding activity of VIP36 using VIP36-streptavidin complex and membrane-based sugar chains.","date":"2006","source":"Journal of biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/17169971","citation_count":26,"is_preprint":false},{"pmid":"24498414","id":"PMC_24498414","title":"Structural basis for disparate sugar-binding specificities in the homologous cargo receptors ERGIC-53 and VIP36.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/24498414","citation_count":25,"is_preprint":false},{"pmid":"15070860","id":"PMC_15070860","title":"The binding of VIP36 and alpha-amylase in the secretory vesicles via high-mannose type glycans.","date":"2004","source":"Glycobiology","url":"https://pubmed.ncbi.nlm.nih.gov/15070860","citation_count":21,"is_preprint":false},{"pmid":"17586539","id":"PMC_17586539","title":"Stable interaction of the cargo receptor VIP36 with molecular chaperone BiP.","date":"2007","source":"Glycobiology","url":"https://pubmed.ncbi.nlm.nih.gov/17586539","citation_count":20,"is_preprint":false},{"pmid":"12871987","id":"PMC_12871987","title":"Localization of VIP36 in the post-Golgi secretory pathway also of rat parotid acinar cells.","date":"2003","source":"The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society","url":"https://pubmed.ncbi.nlm.nih.gov/12871987","citation_count":17,"is_preprint":false},{"pmid":"23269669","id":"PMC_23269669","title":"Site-specific N-linked glycosylation of receptor guanylyl cyclase C regulates ligand binding, ligand-mediated activation and interaction with vesicular integral membrane protein 36, VIP36.","date":"2012","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/23269669","citation_count":15,"is_preprint":false},{"pmid":"34798270","id":"PMC_34798270","title":"Emp47 and Vip36 are required for polarized growth and protein trafficking between ER and Golgi apparatus in opportunistic fungal pathogen Aspergillus fumigatus.","date":"2021","source":"Fungal genetics and biology : FG & B","url":"https://pubmed.ncbi.nlm.nih.gov/34798270","citation_count":8,"is_preprint":false},{"pmid":"28840376","id":"PMC_28840376","title":"Molecular characterization of transport lectin vesicular integral membrane protein 36 kDa (VIP36) in the life cycle of Schistosoma mansoni.","date":"2017","source":"Parasitology research","url":"https://pubmed.ncbi.nlm.nih.gov/28840376","citation_count":5,"is_preprint":false},{"pmid":"39264045","id":"PMC_39264045","title":"Regulation of Kv1.2 Redox-Sensitive Gating by the Transmembrane Lectin LMAN2.","date":"2024","source":"Function (Oxford, England)","url":"https://pubmed.ncbi.nlm.nih.gov/39264045","citation_count":3,"is_preprint":false},{"pmid":"39618331","id":"PMC_39618331","title":"LMAN2 Promotes Breast Cancer Tumorigenesis and Drug Resistance by Interacting With MAPK9 via Activation of the MAPK Pathway.","date":"2024","source":"Cancer medicine","url":"https://pubmed.ncbi.nlm.nih.gov/39618331","citation_count":2,"is_preprint":false},{"pmid":"38219489","id":"PMC_38219489","title":"C-terminal amino acids in the type I transmembrane domain of L-type lectin VIP36 affect γ-secretase susceptibility.","date":"2024","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/38219489","citation_count":2,"is_preprint":false},{"pmid":"39772898","id":"PMC_39772898","title":"LMAN2 interacts with HEATR3 to expedite HER2-positive breast cancer advancement and inflammation and Akt/ERK/NF-κB signaling.","date":"2025","source":"Biochemistry and cell biology = Biochimie et biologie cellulaire","url":"https://pubmed.ncbi.nlm.nih.gov/39772898","citation_count":1,"is_preprint":false},{"pmid":"39659243","id":"PMC_39659243","title":"Competitive modulation of KV1.2 gating by LMAN2 and Slc7a5.","date":"2024","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/39659243","citation_count":1,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.07.25.605230","title":"Competitive modulation of Kv1.2 gating by LMAN2 and Slc7a5","date":"2024-07-26","source":"bioRxiv","url":"https://doi.org/10.1101/2024.07.25.605230","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":15730,"output_tokens":5182,"usd":0.06246,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":13480,"output_tokens":5072,"usd":0.0971,"stage2_stop_reason":"end_turn"},"total_usd":0.15956,"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\": 1994,\n      \"finding\": \"VIP36 (LMAN2) was purified from CHAPS-insoluble (glycolipid raft) fractions of MDCK cells and its cDNA was isolated; the N-terminal 31 kDa luminal domain shows homology to leguminous plant lectins. Transiently expressed VIP36 localizes to the Golgi apparatus, endosomal/vesicular structures, and the plasma membrane, consistent with a role in Golgi-to-cell-surface transport.\",\n      \"method\": \"Biochemical purification, cDNA cloning, immunofluorescence/subcellular localization of transiently expressed protein\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — original isolation and localization by multiple methods (purification, cDNA, imaging) in a single foundational study\",\n      \"pmids\": [\"8157011\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"The recombinant luminal/exoplasmic domain of VIP36 binds Ca2+ and can decorate internal membrane structures of MDCK cells in vitro; this binding requires Ca2+ and is specifically inhibited by N-acetyl-D-galactosamine. Glycopeptides from galactose-labeled cells bind to VIP36 and can be eluted with N-acetyl-D-galactosamine, demonstrating lectin activity.\",\n      \"method\": \"Recombinant protein production, Ca2+ binding assay, in vitro membrane-binding assay, affinity chromatography with competitive inhibition\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro binding assay with specific inhibition, single lab, multiple orthogonal approaches\",\n      \"pmids\": [\"8834812\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Endogenous VIP36 localizes to the Golgi apparatus and the early secretory pathway (ER-Golgi intermediate compartment) of MDCK and Vero cells; it co-localizes with coatomer and ERGIC-53 and cycles in the early secretory pathway as shown by brefeldin A treatment and co-localization with anterograde cargo.\",\n      \"method\": \"High-resolution confocal microscopy, brefeldin A treatment, co-localization with marker proteins (endogenous protein)\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization of endogenous protein using multiple approaches in a single focused study\",\n      \"pmids\": [\"10444376\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"VIP36 specifically recognizes high-mannose type glycans containing alpha1→2 mannosyl residues (Man7-9GlcNAc2) in a pH-optimum of 6.0; the interaction is Ca2+-independent and has an association constant of ~2.1×10^8 M^-1 with thyroglobulin glycans as measured by surface plasmon resonance.\",\n      \"method\": \"GST-fusion protein binding assay, inhibition studies with specific glycans, surface plasmon resonance biosensor\",\n      \"journal\": \"Glycobiology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — quantitative in vitro binding assay with defined ligands and SPR measurement, replicated in subsequent studies\",\n      \"pmids\": [\"10406849\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"VIP36 is localized to the apical membrane of polarized MDCK cells (apical/basolateral ratio ~2); overexpression of wild-type VIP36 increased apical transport and secretion of VIP36-recognized (high-mannose) glycoproteins (including clusterin), while a lectin-inactive mutant had no effect on glycoprotein distribution and inhibited secretion, demonstrating that VIP36 lectin activity is required for apical glycoprotein transport.\",\n      \"method\": \"VIP36 overexpression and lectin-dead mutant expression in polarized MDCK cells, measurement of apical/basolateral distribution and secretion rates\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional mutagenesis in polarized cells with defined cargo readout, single lab\",\n      \"pmids\": [\"11872745\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Endogenous VIP36 localizes to the trans-Golgi network, immature secretory granules, and mature secretory granules in rat parotid acinar cells, co-localizing with alpha-amylase in apical regions, indicating a post-Golgi secretory pathway role.\",\n      \"method\": \"Immunoelectron microscopy and double-staining immunofluorescence of rat parotid gland tissue (endogenous protein)\",\n      \"journal\": \"The journal of histochemistry and cytochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization of endogenous protein by immunoelectron microscopy in relevant tissue\",\n      \"pmids\": [\"12871987\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"VIP36 physically associates with alpha-amylase in parotid secretory vesicles via high-mannose type glycans; co-precipitation of alpha-amylase with VIP36 was abolished by endo H treatment (removing high-mannose glycans), and alpha-amylase in secretory vesicles carries high-mannose glycans.\",\n      \"method\": \"Subcellular fractionation (Percoll gradient), immunoelectron microscopy, co-immunoprecipitation with endo H treatment\",\n      \"journal\": \"Glycobiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP with enzymatic validation (endo H), co-localization, single lab\",\n      \"pmids\": [\"15070860\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The carbohydrate recognition domain (CRD) of VIP36 selectively binds the deglucosylated trimannose of the D1 branch of high-mannose oligosaccharides with bell-shaped pH dependence (optimum ~6.5), consistent with binding in the cis-Golgi and releasing cargo in the ER (higher pH), suggesting a role in glycoprotein quality control.\",\n      \"method\": \"Frontal affinity chromatography (FAC) with pyridylaminated sugar library (21 oligosaccharides), recombinant CRD\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — quantitative FAC with defined panel of isomeric oligosaccharides, replicated in subsequent studies\",\n      \"pmids\": [\"16129679\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Crystal structures of VIP36 luminal domain (CRD + stalk) in apo, Ca2+-bound, and mannosyl ligand-bound forms reveal a 17-stranded antiparallel beta-sandwich CRD; Ca2+ coordinates Asp131, Asn166, and His190 to enable carbohydrate binding; Man-α1,2-Man-α1,2-Man (D1 arm) is recognized by eight residues via extensive hydrogen bonds, explaining Ca2+-dependent and D1-arm-specific high-mannose glycoprotein recognition.\",\n      \"method\": \"X-ray crystallography of apo, Ca2+, and ligand-bound forms; structure-guided interpretation of substrate specificity\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structures of multiple states with defined active-site residues, provides mechanistic basis replicated by other structural studies\",\n      \"pmids\": [\"17652092\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Frontal affinity chromatography comparing ERGIC-53, VIPL, and VIP36 CRDs showed that VIPL and VIP36 selectively bind deglucosylated trimannose of the D1 branch but with different pH dependence, while ERGIC-53 binds high-mannose oligosaccharides broadly. Structure-based mutagenesis showed that sugar-binding properties of these lectins can be switched by single amino acid substitutions.\",\n      \"method\": \"Frontal affinity chromatography with pyridylaminated sugar library; structure-based site-directed mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — quantitative FAC combined with mutagenesis confirming structural determinants of sugar specificity\",\n      \"pmids\": [\"18025080\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"VIP36 stably interacts with the ER chaperone BiP in an ATP-independent and carbohydrate-independent manner dependent on divalent cations; the interaction occurs in the ER (confirmed by immunoelectron microscopy) and is distinct from canonical chaperone-substrate interactions, suggesting a novel role for VIP36 in quality control of secretory proteins.\",\n      \"method\": \"Chemical crosslinking, co-immunoprecipitation, LC/MS/MS identification, immunoelectron microscopy, surface plasmon resonance with recombinant proteins; lectin-dead mutant used as control\",\n      \"journal\": \"Glycobiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus SPR with recombinant proteins, two orthogonal methods, single lab\",\n      \"pmids\": [\"17586539\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"VIP36 interacts with alpha1-antitrypsin (alpha1-AT) specifically via its high-mannose glycans in Golgi and ER compartments (not the complex glycoform); silencing VIP36 accelerated alpha1-AT transport, arguing against an anterograde role and consistent with a post-ER quality control function where VIP36 recycles alpha1-AT from Golgi back to ER.\",\n      \"method\": \"YFP fragment complementation (bimolecular fluorescence complementation) screen of human liver cDNA library, mutagenesis of glycosylation sites, kifunensine treatment, VIP36 siRNA knockdown with transport kinetics\",\n      \"journal\": \"Traffic (Copenhagen, Denmark)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — unbiased screen followed by multiple orthogonal validations (BiFC, glycosylation mutants, pharmacological intervention, siRNA) in a single rigorous study\",\n      \"pmids\": [\"20477988\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"VIP36 is a target of ectodomain shedding on the cell surface (not in the Golgi/ER) in macrophages; the amount of VIP36 at the cell surface precisely regulates phagocytosis, and shedding of VIP36 is required for this regulation of phagocytic activity.\",\n      \"method\": \"Unbiased proteomic screening (LPS-stimulated macrophage conditioned media), cell surface shedding assay, VIP36 manipulation (overexpression/knockdown) with phagocytosis readout\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — proteomic identification with functional gain/loss-of-function experiment, single lab\",\n      \"pmids\": [\"22016386\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"VIP36 interacts with the receptor guanylyl cyclase GC-C; this interaction depends on glycosylation at specific sites that also allow GC-C to fold properly and bind ligand, identifying GC-C as the first receptor client of VIP36.\",\n      \"method\": \"Co-immunoprecipitation, mutagenesis of 10 glycosylation sites in GC-C, pharmacological inhibition of glycosylation\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP with systematic mutagenesis linking VIP36 binding to specific glycosylation sites, single lab\",\n      \"pmids\": [\"23269669\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Crystal structure of ERGIC-53 CRD in complex with MCFD2 and α1,2-mannotriose revealed a shallower sugar-binding pocket in ERGIC-53 compared to VIP36 due to a single Asp-to-Gly substitution; this structural difference explains the broader sugar specificity of ERGIC-53 versus the D1-arm-specific binding of VIP36.\",\n      \"method\": \"X-ray crystallography of ERGIC-53 CRD/MCFD2/mannotriose complex; structural comparison with VIP36\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — crystal structure with direct structural comparison identifying single amino acid determinant of specificity differences\",\n      \"pmids\": [\"24498414\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"LMAN2 (VIP36) is specifically required for the accumulation of the exosome cargo protein GPRC5B in the Golgi complex and restricts its transport along the exosomal pathway; LMAN2 may interfere with GGA1-mediated trans-Golgi network-to-endosome transport of GPRC5B.\",\n      \"method\": \"Inducible expression system for GPRC5B, LMAN2 knockdown, trafficking assay, co-localization, analysis of GGA1-mediated transport\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — defined cargo with loss-of-function and pathway placement (GGA1), single lab\",\n      \"pmids\": [\"27765817\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LMAN2 co-expression with Kv1.2 causes a large depolarizing shift in channel activation voltage and deceleration of activation kinetics; shRNA knockdown of endogenous LMAN2 reduces Kv1.2 redox sensitivity and gating variability. Kv1.2 sensitivity to LMAN2 requires residues F251 and T252 in the intracellular S2-S3 linker, which also mediate redox-dependent gating, suggesting LMAN2 acts through the same pathway as extracellular redox modulation.\",\n      \"method\": \"Patch-clamp electrophysiology in CHO and L(tk-) cell lines, shRNA knockdown of endogenous LMAN2, Kv1.2 point mutations (F251, T252), functional screening of 52 candidate genes\",\n      \"journal\": \"Function (Oxford, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional gain and loss-of-function with mutagenesis identifying specific channel residues, single lab, multiple cell lines\",\n      \"pmids\": [\"39264045\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LMAN2 and the amino acid transporter Slc7a5 competitively modulate Kv1.2 gating in opposite directions; co-expression of both produces bimodal voltage-dependence suggesting two non-overlapping channel populations. Using Kv1.2:1.5 chimeras, distinct regions in S1-S3 of the voltage-sensing domain are required for LMAN2 versus Slc7a5 sensitivity, confirming that the two regulators compete for interaction with the Kv1.2 voltage sensor.\",\n      \"method\": \"Patch-clamp electrophysiology, Kv1.2:Kv1.5 chimeric channel approach, co-expression of LMAN2 and Slc7a5\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — chimeric channel approach identifies specific VSD segments, functional competition assay, single lab\",\n      \"pmids\": [\"39659243\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"VIP36 (LMAN2) is susceptible to ectodomain shedding followed by gamma-secretase-mediated intramembrane proteolysis (regulated intramembrane proteolysis, RIP); the C-terminal amino acids of its transmembrane domain regulate gamma-secretase susceptibility, as shown by substitution mutant analysis. VIPL, the close homolog, has different gamma-secretase susceptibility despite similar shedding.\",\n      \"method\": \"Substitution mutagenesis of transmembrane domain C-terminal residues, gamma-secretase processing assay, comparison with VIPL mutants\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutagenesis identifying specific TMD residues controlling intramembrane proteolysis, single lab\",\n      \"pmids\": [\"38219489\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"LMAN2 physically interacts with MAPK9 (JNK2) in breast cancer cells and activates the MAPK signaling pathway, promoting cisplatin resistance; knockdown of LMAN2 reduced MAPK pathway activation and sensitized drug-resistant cells to cisplatin in vivo.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence co-localization, siRNA knockdown, tumor xenograft model\",\n      \"journal\": \"Cancer medicine\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP identifying interaction with MAPK9, pathway activation inferred from downstream markers, single lab\",\n      \"pmids\": [\"39618331\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"LMAN2 (VIP36) is a type I transmembrane L-type lectin of the early secretory pathway that cycles between the ER and cis/medial-Golgi; its luminal carbohydrate recognition domain (17-stranded beta-sandwich) binds high-mannose N-glycans carrying the intact α1,2-linked D1 mannosyl arm in a Ca²⁺-dependent manner with pH optimum ~6.5, enabling it to capture glycoprotein cargo (e.g., alpha1-antitrypsin, GC-C, alpha-amylase) in the Golgi and recycle them to the ER for post-ER quality control; at the cell surface it undergoes ADAM-mediated ectodomain shedding (regulated by C-terminal transmembrane residues for subsequent gamma-secretase processing) that controls macrophage phagocytosis; LMAN2 also facilitates apical sorting of high-mannose glycoproteins in polarized epithelial cells, restricts exosome cargo (GPRC5B) exit from the Golgi via interference with GGA1-mediated transport, and acts as a regulatory auxiliary protein for Kv1.2 potassium channels by shifting their voltage-dependence toward depolarized potentials through interaction with the S2-S3 intracellular linker, competing with the Slc7a5 transporter for the channel voltage-sensing domain.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"LMAN2 (VIP36) is a type I transmembrane L-type lectin of the early secretory pathway that recognizes high-mannose N-glycans and recycles glycoprotein cargo between the Golgi and the ER as part of post-ER quality control [#0, #3, #11]. Its luminal carbohydrate recognition domain is a 17-stranded antiparallel beta-sandwich that coordinates Ca²⁺ through Asp131, Asn166, and His190 and engages the α1,2-linked D1 trimannose arm of Man7-9GlcNAc2 oligosaccharides through extensive hydrogen bonding by eight residues [#8]. Binding is D1-arm-specific with a bell-shaped pH optimum near 6.5, a property that favors cargo capture in the acidic cis-Golgi and release at the higher pH of the ER; a single amino acid difference distinguishes this narrow specificity from the broader high-mannose binding of the related lectin ERGIC-53 [#7, #9, #14]. Through this glycan-dependent recognition LMAN2 captures clients including alpha1-antitrypsin, the receptor guanylyl cyclase GC-C, and alpha-amylase, and silencing LMAN2 accelerates alpha1-antitrypsin transport, consistent with a retrograde Golgi-to-ER recycling role rather than an anterograde one [#6, #11, #13]. The lectin also localizes apically in polarized epithelial cells where its carbohydrate activity is required for apical transport and secretion of high-mannose glycoproteins, and it restricts exosome cargo GPRC5B exit from the Golgi by interfering with GGA1-mediated transport [#4, #15]. Beyond the secretory pathway, LMAN2 reaches the cell surface where it undergoes ADAM-type ectodomain shedding followed by gamma-secretase-mediated intramembrane proteolysis governed by C-terminal transmembrane residues, with surface levels controlling macrophage phagocytosis [#12, #18]. LMAN2 additionally functions as an auxiliary regulator of Kv1.2 potassium channels, producing a depolarizing shift in activation voltage through the intracellular S2-S3 linker (residues F251/T252) and competing with the Slc7a5 transporter for the channel voltage-sensing domain [#16, #17].\",\n  \"teleology\": [\n    {\n      \"year\": 1994,\n      \"claim\": \"Establishing the existence and trafficking itinerary of VIP36 was the first step, framing it as a membrane protein of the Golgi-to-cell-surface route with lectin homology.\",\n      \"evidence\": \"Biochemical purification from MDCK raft fractions, cDNA cloning, and imaging of transiently expressed protein\",\n      \"pmids\": [\"8157011\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Overexpression localization may not reflect endogenous steady state\", \"No glycan ligand defined\", \"No functional cargo identified\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Demonstrating Ca²⁺-dependent, sugar-competable binding confirmed VIP36 is a functional lectin rather than merely a lectin-homologous protein.\",\n      \"evidence\": \"Recombinant luminal domain Ca²⁺ and membrane-binding assays with GalNAc inhibition and glycopeptide affinity chromatography\",\n      \"pmids\": [\"8834812\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"GalNAc-based specificity later revised toward high-mannose glycans\", \"Physiological ligand not yet defined\", \"No structural basis for binding\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Localizing the endogenous protein to the ERGIC and defining its high-mannose D1-arm specificity established VIP36 as a recycling early-secretory-pathway lectin with a pH-tuned binding profile.\",\n      \"evidence\": \"Confocal microscopy with brefeldin A and ERGIC-53/coatomer co-localization; SPR and inhibition with defined glycans\",\n      \"pmids\": [\"10444376\", \"10406849\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direction of cargo flow (anterograde vs retrograde) not resolved\", \"Endogenous cargo not identified\", \"Ca²⁺ dependence reported inconsistently between binding studies\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Functional mutagenesis showed lectin activity is required for apical glycoprotein transport, assigning VIP36 a sorting role in polarized cells.\",\n      \"evidence\": \"Wild-type and lectin-dead VIP36 expression in polarized MDCK cells with apical/basolateral cargo distribution and secretion readouts\",\n      \"pmids\": [\"11872745\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of apical sorting not defined\", \"Generality beyond MDCK unclear\", \"Conflicts with later retrograde quality-control model\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Tissue localization to secretory granules of parotid acinar cells, and glycan-dependent co-precipitation with alpha-amylase, identified a physiological client engaged through high-mannose glycans.\",\n      \"evidence\": \"Immunoelectron microscopy of rat parotid gland and co-IP with endo H sensitivity\",\n      \"pmids\": [\"12871987\", \"15070860\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence for amylase secretion not tested\", \"Single tissue system\", \"Direct vs indirect association not fully separated\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Defining the bell-shaped pH dependence of D1-trimannose binding provided a physical model for cargo capture in the cis-Golgi and release in the ER, framing a quality-control cycle.\",\n      \"evidence\": \"Frontal affinity chromatography of recombinant CRD against a pyridylaminated oligosaccharide library\",\n      \"pmids\": [\"16129679\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct demonstration of pH-driven cargo release in cells not shown\", \"Cargo set still limited\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Crystal structures and comparative FAC/mutagenesis defined the atomic basis of Ca²⁺-dependent D1-arm recognition and showed how single residues tune specificity across the VIP36/VIPL/ERGIC-53 lectin family.\",\n      \"evidence\": \"X-ray structures of apo, Ca²⁺-bound, and ligand-bound luminal domain; FAC with structure-guided point mutagenesis\",\n      \"pmids\": [\"17652092\", \"18025080\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structures do not capture cargo glycoprotein engagement\", \"pH-dependent conformational switch not visualized\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Identifying a stable, carbohydrate-independent interaction with the ER chaperone BiP linked VIP36 to a non-canonical quality-control function beyond its lectin activity.\",\n      \"evidence\": \"Crosslinking, reciprocal co-IP with LC/MS/MS, immunoelectron microscopy, and SPR with lectin-dead control\",\n      \"pmids\": [\"17586539\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of BiP binding not established\", \"Stoichiometry and cellular context unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identifying alpha1-antitrypsin as a glycan-dependent client and showing that knockdown accelerates its transport resolved the trafficking direction, establishing VIP36 as a post-ER retrograde quality-control receptor.\",\n      \"evidence\": \"BiFC screen of human liver cDNA, glycosylation-site mutants, kifunensine treatment, and siRNA transport kinetics\",\n      \"pmids\": [\"20477988\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative contribution to ER retention not measured\", \"Reconciliation with apical anterograde role incomplete\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Discovery of cell-surface ectodomain shedding controlling macrophage phagocytosis revealed a functional role for VIP36 outside the secretory pathway.\",\n      \"evidence\": \"Proteomic screen of macrophage conditioned media with surface shedding assay and gain/loss-of-function phagocytosis readout\",\n      \"pmids\": [\"22016386\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Sheddase identity not pinned down here\", \"Mechanism linking surface levels to phagocytosis unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Identifying the receptor guanylyl cyclase GC-C as a glycosylation-dependent client extended the client repertoire to a signaling receptor whose folding correlates with VIP36 binding.\",\n      \"evidence\": \"Co-IP with systematic mutagenesis of ten GC-C glycosylation sites and glycosylation inhibition\",\n      \"pmids\": [\"23269669\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct vs glycan-bridged interaction not fully separated\", \"Effect on GC-C trafficking not quantified\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Structural comparison of the ERGIC-53/MCFD2 complex with VIP36 pinpointed a single Asp-to-Gly substitution as the determinant of their divergent glycan specificities.\",\n      \"evidence\": \"X-ray crystallography of ERGIC-53 CRD/MCFD2/mannotriose complex with structural comparison\",\n      \"pmids\": [\"24498414\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No bound MCFD2-equivalent partner for VIP36 identified\", \"Functional consequence of pocket depth in cells not tested\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Showing that LMAN2 retains GPRC5B in the Golgi and restricts its exosomal exit via GGA1 placed the lectin in a pathway controlling cargo partitioning into the exosomal route.\",\n      \"evidence\": \"Inducible GPRC5B expression, LMAN2 knockdown, trafficking and co-localization assays with GGA1 analysis\",\n      \"pmids\": [\"27765817\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct LMAN2-GPRC5B interaction not defined\", \"Mechanism of GGA1 interference unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Electrophysiology defined a previously unknown role for LMAN2 as a Kv1.2 auxiliary regulator, shifting activation voltage through the S2-S3 linker and competing with Slc7a5 at the voltage-sensing domain.\",\n      \"evidence\": \"Patch-clamp in CHO and L(tk-) cells, shRNA knockdown, Kv1.2 point mutations (F251/T252) and Kv1.2:1.5 chimeras with Slc7a5 co-expression\",\n      \"pmids\": [\"39264045\", \"39659243\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether regulation requires lectin activity unknown\", \"Physiological setting and stoichiometry undefined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Mapping gamma-secretase-mediated intramembrane proteolysis to specific C-terminal transmembrane residues extended the surface-shedding pathway into regulated intramembrane proteolysis.\",\n      \"evidence\": \"Substitution mutagenesis of TMD C-terminal residues with gamma-secretase processing assay and VIPL comparison\",\n      \"pmids\": [\"38219489\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Fate and function of released intracellular fragment unknown\", \"Physiological trigger for RIP unclear\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"A reported interaction with MAPK9 (JNK2) tied LMAN2 to MAPK-driven cisplatin resistance in breast cancer, an emerging disease-context role.\",\n      \"evidence\": \"Co-IP, co-localization, siRNA knockdown and xenograft cisplatin sensitivity\",\n      \"pmids\": [\"39618331\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single Co-IP without reciprocal validation\", \"Pathway activation inferred from downstream markers only\", \"Direct vs indirect interaction unresolved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how LMAN2's glycan-recognition activity mechanistically relates to its non-lectin functions at the cell surface (shedding/RIP, phagocytosis) and at ion channels (Kv1.2 regulation).\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Whether channel regulation and surface functions require the CRD is untested\", \"No integrated model linking secretory and plasma-membrane roles\", \"Native interactomes for non-glycan partners not mapped\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0030246\", \"supporting_discovery_ids\": [1, 3, 7, 8]},\n      {\"term_id\": \"GO:0038024\", \"supporting_discovery_ids\": [11, 13]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [16, 17]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [0, 2, 5, 15]},\n      {\"term_id\": \"GO:0005783\", \"supporting_discovery_ids\": [2, 10, 11]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 12, 18]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [4, 11, 15]},\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [11, 15]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [11, 13]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"HSPA5\", \"SERPINA1\", \"GUCY2C\", \"AMY1\", \"GPRC5B\", \"KCNA2\", \"SLC7A5\", \"MAPK9\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}