{"gene":"MAGI3","run_date":"2026-06-10T02:59:50","timeline":{"discoveries":[{"year":2000,"finding":"MAGI3 localizes to epithelial cell tight junctions and its PDZ domain directly binds the PDZ-binding motif of the tumor suppressor PTEN/MMAC. MAGI3 and PTEN cooperate to modulate AKT/PKB kinase activity, suggesting MAGI3 scaffolds PTEN to phospholipid signaling pathways.","method":"Co-immunoprecipitation, pulldown, subcellular localization (tight junction), functional AKT kinase assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal binding assays combined with functional AKT kinase readout; foundational paper replicated by multiple downstream studies","pmids":["10748157"],"is_preprint":false},{"year":2002,"finding":"High-risk HPV E6 oncoproteins target MAGI-3 for proteasome-mediated degradation via a specific PDZ domain interaction; overexpression of that PDZ domain alone protects full-length MAGI-3 from E6-mediated degradation.","method":"Co-expression degradation assays, dominant-negative PDZ domain competition, proteasome inhibitor experiments","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 / Strong — mechanistic rescue experiment with PDZ domain fragment plus proteasome inhibition, replicated across MAGI-2 and MAGI-3 and confirmed in independent study (PMID:18518978)","pmids":["12140759"],"is_preprint":false},{"year":2003,"finding":"MAGI-3 interacts with the cytoplasmic region of receptor protein tyrosine phosphatase beta (RPTPβ) via PDZ domains. MAGI-3 localizes to tight junctions (with ZO-1 and cingulin) in epithelial cells, to E-cadherin contacts and focal adhesions in astrocytes, and is also found in the nucleus. MAGI-3 associates with tyrosine-phosphorylated substrates of RPTPβ (a 130 kDa protein in glioblastoma cells, 90 kDa in Caco2), and the RPTPβ–MAGI-3 interaction is required for efficient dephosphorylation of p130 by RPTPβ.","method":"Yeast two-hybrid, co-immunoprecipitation, pulldown, immunofluorescence, immunoelectron microscopy, vanadate treatment, phosphatase substrate assay","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (Y2H, Co-IP, pulldown, localization, phosphatase activity) in a single focused study","pmids":["12615970"],"is_preprint":false},{"year":2004,"finding":"MAGI-3 acts as a scaffold protein that specifically binds frizzled-4 and frizzled-7 (but not other frizzleds) via their PDZ-binding motifs, and also binds Ltap (mouse homolog of Drosophila strabismus). These three molecules form a ternary complex that colocalizes at epithelial cell contact sites. MAGI-3 strongly activates JNK in conjunction with frizzled-4 and Ltap, and this activation requires the small GTPase Rac.","method":"Co-immunoprecipitation, pulldown, colocalization (immunofluorescence), JNK activation assay, dominant-negative Rac experiment","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 / Moderate — ternary complex formation confirmed by Co-IP plus functional JNK assay with Rac dependence in a single focused study","pmids":["15195140"],"is_preprint":false},{"year":2004,"finding":"HTLV-1 Tax1 (but not Tax2) physically interacts with MAGI-3 in a PDZ-binding motif-dependent manner. This interaction alters the subcellular localization of both Tax1 and MAGI-3, and correlates with the higher transforming activity of Tax1 relative to Tax2.","method":"Differential display, RT-PCR, co-immunoprecipitation, subcellular localization (immunofluorescence), transformation assay","journal":"Virology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP and localization change demonstrated but mechanistic link to transformation is correlative; single lab","pmids":["15003862"],"is_preprint":false},{"year":2005,"finding":"MAGI-3 binds to the PDZ-recognition motif (TVV) at the C-terminus of pro-TGFα via its PDZ-1 domain (but not MAGI-1's PDZ-1). MAGI-3 forms a stable complex with membrane-fixed TGFα early in the secretory pathway, and overexpression of MAGI-3 increases TGFα levels in the basolateral medium of polarized MDCK cells, indicating a role in basolateral trafficking of TGFα.","method":"Yeast two-hybrid, in vitro PDZ domain binding assay, co-immunoprecipitation, co-localization (immunofluorescence), polarized secretion assay (MDCK cells)","journal":"Experimental cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Y2H, in vitro binding, Co-IP, and functional trafficking assay, single lab","pmids":["15652357"],"is_preprint":false},{"year":2006,"finding":"MAGI-3 specifically interacts with LPA2 receptor (but not LPA1 or LPA3) via its fifth PDZ domain binding the C-terminal four amino acids of LPA2; mutation of these residues abolishes binding. MAGI-3 is required for LPA-induced ERK activation (silencing inhibits ERK activation) and overexpression of MAGI-3 stimulates LPA-induced RhoA activation.","method":"PDZ domain proteomic array screen, co-affinity purification, siRNA knockdown, ERK/RhoA activation assays, mutational analysis of LPA2 C-terminus","journal":"Cellular signalling","confidence":"High","confidence_rationale":"Tier 2 / Moderate — binding confirmed biochemically with mutational validation plus functional signaling readouts (ERK, RhoA) using both OE and KD; single lab","pmids":["16904289"],"is_preprint":false},{"year":2008,"finding":"HPV E6-mediated degradation of MAGI-3 is mechanistically distinct from E6-mediated p53 degradation: proteasome inhibition does not protect MAGI-3 (unlike p53), and MAGI-3 is not ubiquitinated by E6 under conditions where p53 is ubiquitinated by E6/MDM2.","method":"Proteasome inhibitor assays, in vivo ubiquitination assay","journal":"Virology journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — parallel mechanistic comparison with two orthogonal assays (proteasome inhibition, ubiquitination); single lab","pmids":["18518978"],"is_preprint":false},{"year":2010,"finding":"MAGI-3 binds β2-adrenergic receptor (β2AR) constitutively via the fifth PDZ domain interacting with the C-terminal DSLL motif of the receptor; agonist stimulation enhances the interaction. MAGI-3 expression substantially retards β2AR-stimulated ERK1/2 activation.","method":"Co-immunoprecipitation, PDZ domain binding assay, ERK activation assay with MAGI-3 overexpression","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP and functional ERK assay; single lab, single study","pmids":["20353789"],"is_preprint":false},{"year":2010,"finding":"MAGI-3 competes with NHERF-2 for binding to LPA2 receptor and phospholipase C-β3. MAGI-3 increases LPA2–Gα12 coupling while NHERF-2 promotes LPA2–Gαq coupling, and MAGI-3 acts as a negative regulator of LPA2-induced phospholipase C activity, cell migration, invasion, NF-κB activation, and JNK activity.","method":"Overexpression and siRNA knockdown, co-immunoprecipitation, phospholipase C (inositol phosphate) assay, NF-κB reporter assay, migration/invasion assays","journal":"Gastroenterology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal functional assays with both OE and KD plus G-protein coupling analysis; single lab","pmids":["21134377"],"is_preprint":false},{"year":2015,"finding":"MAGI3 overexpression in glioma cells upregulates PTEN protein expression, inhibits Akt phosphorylation, and suppresses proliferation; MAGI3 loss downregulates PTEN, activating the PI3K/Akt pathway.","method":"Stable transfection (overexpression), Western blot, xenograft tumor growth assay, GSEA of GEO dataset","journal":"Biomedical and environmental sciences : BES","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — functional OE with mechanistic western blot readout and in vivo xenograft; single lab, single method per endpoint","pmids":["26248734"],"is_preprint":false},{"year":2015,"finding":"MAGI3 directly binds β-catenin through its PDZ domains interacting with the PDZ-binding motif of β-catenin. MAGI3 overexpression inhibits β-catenin transcriptional activity and suppresses expression of β-catenin target genes (Cyclin D1, Axin2); MAGI3 knockdown enhances their expression. This inhibits glioma cell proliferation, migration, and cell cycle progression.","method":"GST pulldown, co-immunoprecipitation, β-catenin luciferase reporter assay, Western blot, overexpression and knockdown, xenograft tumor assay","journal":"Oncotarget","confidence":"High","confidence_rationale":"Tier 2 / Moderate — direct binding confirmed by GST pulldown and Co-IP, functional transcriptional reporter, and in vivo xenograft; single lab, multiple orthogonal methods","pmids":["26452219"],"is_preprint":false},{"year":2016,"finding":"Premature cleavage and polyadenylation of MAGI3 produces a truncated protein isoform (MAGI3-pPA) that acts in a dominant-negative manner to prevent full-length MAGI3 from interacting with the YAP oncoprotein, thereby relieving YAP inhibition and promoting malignant transformation of human mammary epithelial cells.","method":"RNA isoform identification, dominant-negative overexpression, co-immunoprecipitation (full-length MAGI3–YAP interaction), transformation assay in mammary epithelial cells","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Moderate — Co-IP showing disruption of MAGI3–YAP interaction combined with functional transformation assay; single lab, two orthogonal approaches","pmids":["27205883"],"is_preprint":false},{"year":2020,"finding":"MAGI3 physically interacts with β-catenin to regulate its transcriptional activity and c-Myc expression, which controls glycolytic gene expression (HK2, PFKL, LDHA) and the Warburg effect in hepatocellular carcinoma cells.","method":"Co-immunoprecipitation, β-catenin transcriptional activity assay, glycolysis functional assays (ECAR, lactate production, glucose consumption), Western blot","journal":"FASEB journal","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP plus functional glycolysis readouts; single lab, confirmation of existing β-catenin interaction mechanism","pmids":["32080912"],"is_preprint":false},{"year":2021,"finding":"HPV18 E6 reduces MAGI3 protein levels, activating Wnt/β-catenin signaling and promoting cervical cancer cell migration and invasion via increased β-catenin levels; MAGI3 itself inhibits β-catenin levels and suppresses migration/invasion.","method":"Knockdown and overexpression of MAGI3, E6 expression, Western blot for β-catenin, migration/invasion assays","journal":"FEBS open bio","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — functional KD/OE with mechanistic signaling readout; single lab, single study","pmids":["34510826"],"is_preprint":false},{"year":2022,"finding":"MAGI3 functions as a novel substrate-recognition subunit of a SKP1-Cullin E3 ubiquitin ligase complex that binds c-Myc and promotes its ubiquitination and proteasomal degradation, thereby inhibiting CRC cell growth and promoting chemosensitivity.","method":"Co-immunoprecipitation, GST pulldown, ubiquitination assay, Western blot, cell proliferation/apoptosis assays, xenograft assay","journal":"Molecular cancer","confidence":"High","confidence_rationale":"Tier 1-2 / Moderate — direct ubiquitination assay, GST pulldown, Co-IP plus in vitro and in vivo functional validation; single lab, multiple orthogonal methods","pmids":["35864508"],"is_preprint":false},{"year":2026,"finding":"MAGI3 binds the C-terminus of β-catenin via its PDZ domains and disrupts intramolecular N-terminus–ARM domain interactions within β-catenin, thereby exposing phosphorylation sites and enabling GSK-3β-mediated phosphorylation and ubiquitin-dependent degradation of β-catenin. Loss of MAGI3 hyperactivates β-catenin and drives mTOR inhibitor resistance in ccRCC.","method":"Multi-omics analysis, co-immunoprecipitation, PDZ domain binding assays, phosphorylation and ubiquitination assays, invasion/migration assays, in vivo metastasis assay, drug resistance assay","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — Co-IP and functional assays with mechanistic model of conformational change; single lab, novel conformational mechanism not yet independently replicated","pmids":["41876458"],"is_preprint":false}],"current_model":"MAGI3 is a multi-PDZ/WW domain scaffold protein that localizes to tight junctions and cell–cell contacts, where it suppresses oncogenic signaling through several mechanisms: it directly binds PTEN via a PDZ interaction to modulate AKT activity; it binds β-catenin via PDZ domains to promote GSK-3β-mediated phosphorylation and ubiquitin-dependent degradation of β-catenin, suppressing Wnt target gene expression; it acts as a substrate-recognition subunit of a SKP1-Cullin E3 ligase to ubiquitinate and degrade c-Myc; it scaffolds RPTPβ with its substrates at the plasma membrane; it organizes frizzled-4/Ltap complexes to activate JNK via Rac; it negatively regulates LPA2-, β2AR-, and frizzled-mediated signaling by competing with pro-oncogenic PDZ proteins; and it is itself targeted for degradation by HPV E6 oncoproteins (via a non-ubiquitin-dependent proteasomal route) and by premature polyadenylation that generates a dominant-negative truncated isoform which prevents full-length MAGI3 from restraining YAP activity."},"narrative":{"mechanistic_narrative":"MAGI3 is a multi-PDZ/WW domain scaffold protein at epithelial tight junctions and cell–cell contacts that restrains multiple oncogenic signaling pathways by physically organizing receptors, phosphatases, and signaling effectors at the membrane [PMID:10748157, PMID:12615970]. Through its PDZ domains it directly binds the tumor suppressor PTEN to modulate AKT/PKB activity, and MAGI3 levels positively control PTEN protein and suppress PI3K/Akt signaling and proliferation [PMID:10748157, PMID:26248734]. A central tumor-suppressive function is the negative regulation of β-catenin: MAGI3 binds the C-terminal PDZ-binding motif of β-catenin, disrupting its intramolecular N-terminus–ARM interaction to expose phosphorylation sites, enabling GSK-3β-mediated phosphorylation and ubiquitin-dependent degradation, thereby suppressing β-catenin transcriptional output (Cyclin D1, Axin2, c-Myc) and downstream programs including the Warburg effect [PMID:26452219, PMID:32080912, PMID:41876458]. MAGI3 also acts as the substrate-recognition subunit of a SKP1-Cullin E3 ubiquitin ligase that ubiquitinates c-Myc for proteasomal degradation [PMID:35864508]. As a PDZ scaffold it engages numerous transmembrane partners—RPTPβ and its tyrosine-phosphorylated substrates [PMID:12615970], frizzled-4/-7 and Ltap to activate JNK through Rac [PMID:15195140], LPA2 and β2-adrenergic receptors where it competes with pro-oncogenic PDZ proteins such as NHERF-2 to bias G-protein coupling and dampen ERK/RhoA/PLC signaling [PMID:16904289, PMID:20353789, PMID:21134377], and pro-TGFα for basolateral trafficking [PMID:15652357]. MAGI3's growth-restraining activity is antagonized by viral oncoproteins (HPV E6 drives its proteasomal degradation by a ubiquitin-independent route; HTLV-1 Tax1 mislocalizes it) and by premature cleavage/polyadenylation that yields a dominant-negative truncated isoform releasing YAP from inhibition [PMID:12140759, PMID:18518978, PMID:15003862, PMID:27205883, PMID:34510826].","teleology":[{"year":2000,"claim":"Established MAGI3 as a tight-junction scaffold that physically tethers the tumor suppressor PTEN to modulate AKT signaling, defining its first growth-regulatory function.","evidence":"Co-IP, pulldown, tight-junction localization, and AKT kinase assay in epithelial cells","pmids":["10748157"],"confidence":"High","gaps":["Did not establish stoichiometry or whether PTEN catalytic regulation is direct","No in vivo phenotype for the MAGI3–PTEN axis"]},{"year":2002,"claim":"Showed MAGI3 is a target of high-risk HPV E6 oncoproteins, framing its degradation as part of viral transformation and implying a tumor-suppressive role.","evidence":"Co-expression degradation assays with dominant-negative PDZ competition and proteasome inhibition","pmids":["12140759"],"confidence":"High","gaps":["Mechanism of degradation not resolved here","Endogenous consequence of MAGI3 loss not measured"]},{"year":2003,"claim":"Defined MAGI3 as a PDZ scaffold for receptor tyrosine phosphatase RPTPβ required for efficient substrate dephosphorylation, broadening its role to organizing phosphatase–substrate complexes.","evidence":"Y2H, Co-IP, pulldown, immuno-EM localization, and phosphatase substrate assay in glioblastoma and Caco2 cells","pmids":["12615970"],"confidence":"High","gaps":["Identity of the 130/90 kDa substrates not determined","Functional consequence of altered substrate phosphorylation unclear"]},{"year":2004,"claim":"Demonstrated MAGI3 nucleates a frizzled-4/-7–Ltap ternary complex that activates JNK via Rac, and that HTLV-1 Tax1 binds and relocalizes MAGI3, linking the scaffold to planar/non-canonical Wnt signaling and viral transformation.","evidence":"Co-IP, colocalization, JNK activation with dominant-negative Rac; differential display and transformation assay for Tax1","pmids":["15195140","15003862"],"confidence":"Medium","gaps":["Tax1–transformation link is correlative","Physiological context for frizzled-driven JNK activation not defined"]},{"year":2006,"claim":"Identified MAGI3 as a selective LPA2-receptor partner required for LPA-induced ERK and RhoA signaling, showing the scaffold can both promote and restrain receptor outputs depending on context.","evidence":"PDZ proteomic array, co-affinity purification, LPA2 C-terminal mutagenesis, siRNA, ERK/RhoA assays","pmids":["16904289"],"confidence":"High","gaps":["Did not reconcile positive ERK/RhoA role with later negative regulatory findings","Downstream cellular phenotype not assessed"]},{"year":2008,"claim":"Resolved the mechanism of HPV E6-mediated MAGI3 loss as ubiquitin-independent and proteasome-resistant, mechanistically distinguishing it from E6/MDM2-driven p53 degradation.","evidence":"Proteasome inhibitor and in vivo ubiquitination assays comparing MAGI3 and p53","pmids":["18518978"],"confidence":"Medium","gaps":["The actual proteolytic route remains undefined","Single lab"]},{"year":2010,"claim":"Established MAGI3 as a negative regulator of GPCR signaling that biases G-protein coupling by competing with NHERF-2 at LPA2 and binds β2AR, dampening ERK, PLC, NF-κB, migration and invasion.","evidence":"Co-IP, PDZ binding assays, inositol phosphate/NF-κB reporter, migration/invasion assays with OE and KD","pmids":["21134377","20353789"],"confidence":"High","gaps":["How MAGI3 selects Gα12 vs Gαq coupling structurally is unknown","Relationship to its earlier positive ERK role at LPA2 unresolved"]},{"year":2015,"claim":"Defined MAGI3 as a direct β-catenin binder that suppresses Wnt transcriptional output and tumor growth, and confirmed its PTEN/Akt-suppressive role in glioma, consolidating its tumor-suppressor identity.","evidence":"GST pulldown, Co-IP, β-catenin luciferase reporter, OE/KD, and xenograft assays in glioma","pmids":["26452219","26248734"],"confidence":"High","gaps":["Did not specify how MAGI3 binding promotes β-catenin degradation","Endogenous-level requirement in normal tissue untested"]},{"year":2016,"claim":"Revealed a regulatory mechanism by which premature cleavage/polyadenylation generates a dominant-negative MAGI3 isoform that blocks the full-length protein from inhibiting YAP, promoting transformation.","evidence":"RNA isoform identification, dominant-negative OE, MAGI3–YAP Co-IP, and transformation assay in mammary epithelial cells","pmids":["27205883"],"confidence":"High","gaps":["The MAGI3–YAP binding interface not mapped","Prevalence of the truncated isoform in primary tumors not quantified"]},{"year":2022,"claim":"Showed MAGI3 itself functions as a substrate-recognition subunit of a SKP1-Cullin E3 ligase that ubiquitinates c-Myc for degradation, adding an enzymatic adaptor role beyond passive scaffolding.","evidence":"Co-IP, GST pulldown, ubiquitination assay, proliferation/apoptosis and xenograft assays in colorectal cancer","pmids":["35864508"],"confidence":"High","gaps":["The specific Cullin/F-box partners were not fully defined","How this E3 role integrates with β-catenin-mediated c-Myc control is unclear"]},{"year":2026,"claim":"Provided a structural mechanism for β-catenin regulation: MAGI3 binding disrupts β-catenin's intramolecular N-terminus–ARM interaction to expose GSK-3β phosphorylation sites and license its degradation, with loss driving mTOR-inhibitor resistance.","evidence":"Multi-omics, Co-IP, PDZ binding, phosphorylation/ubiquitination assays, metastasis and drug-resistance assays in ccRCC","pmids":["41876458"],"confidence":"Medium","gaps":["Conformational model not yet independently replicated","No direct structural data for the proposed β-catenin conformational change"]},{"year":null,"claim":"How MAGI3's distinct activities—PDZ scaffolding, E3 ligase adaptor function, and conformational regulation of β-catenin—are coordinated and selected in different tissues remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of full-length MAGI3 multivalent assembly","Tissue-specific partner selection rules undefined","No germline loss-of-function disease association established in the corpus"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,2,3,6,9]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[9,11,16]},{"term_id":"GO:0016874","term_label":"ligase activity","supporting_discovery_ids":[15]},{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[15]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,2,6,8]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[2]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,3,6,9,11]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[15,16]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[1,12,14]}],"complexes":["SKP1-Cullin E3 ubiquitin ligase","frizzled-4/Ltap ternary complex"],"partners":["PTEN","CTNNB1","MYC","PTPRB","FZD4","LPAR2","ADRB2","YAP1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q5TCQ9","full_name":"Membrane-associated guanylate kinase, WW and PDZ domain-containing protein 3","aliases":["Membrane-associated guanylate kinase inverted 3","MAGI-3"],"length_aa":1481,"mass_kda":162.9,"function":"Acts as a scaffolding protein at cell-cell junctions, thereby regulating various cellular and signaling processes. Cooperates with PTEN to modulate the kinase activity of AKT1. Its interaction with PTPRB and tyrosine phosphorylated proteins suggests that it may link receptor tyrosine phosphatase with its substrates at the plasma membrane. In polarized epithelial cells, involved in efficient trafficking of TGFA to the cell surface. Regulates the ability of LPAR2 to activate ERK and RhoA pathways. Regulates the JNK signaling cascade via its interaction with FZD4 and VANGL2","subcellular_location":"Cell membrane; Cell junction, tight junction; Nucleus","url":"https://www.uniprot.org/uniprotkb/Q5TCQ9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MAGI3","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/MAGI3","total_profiled":1310},"omim":[{"mim_id":"615943","title":"MEMBRANE-ASSOCIATED GUANYLATE KINASE, WW AND PDZ DOMAINS-CONTAINING, 3; MAGI3","url":"https://www.omim.org/entry/615943"},{"mim_id":"612258","title":"MICROTUBULE-ASSOCIATED SERINE/THREONINE KINASE 3; MAST3","url":"https://www.omim.org/entry/612258"},{"mim_id":"612257","title":"MICROTUBULE-ASSOCIATED SERINE/THREONINE KINASE 2; MAST2","url":"https://www.omim.org/entry/612257"},{"mim_id":"612256","title":"MICROTUBULE-ASSOCIATED SERINE/THREONINE KINASE 1; MAST1","url":"https://www.omim.org/entry/612256"},{"mim_id":"611223","title":"AKT SERINE/THREONINE KINASE 3; AKT3","url":"https://www.omim.org/entry/611223"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cell Junctions","reliability":"Supported"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"retina","ntpm":32.2}],"url":"https://www.proteinatlas.org/search/MAGI3"},"hgnc":{"alias_symbol":["MAGI-3"],"prev_symbol":[]},"alphafold":{"accession":"Q5TCQ9","domains":[{"cath_id":"2.30.42.10","chopping":"12-143_193-220","consensus_level":"high","plddt":76.879,"start":12,"end":220},{"cath_id":"2.20.70.10","chopping":"294-379","consensus_level":"medium","plddt":80.2741,"start":294,"end":379},{"cath_id":"2.30.42.10","chopping":"408-493","consensus_level":"high","plddt":91.6647,"start":408,"end":493},{"cath_id":"2.30.42.10","chopping":"576-655","consensus_level":"high","plddt":88.9034,"start":576,"end":655},{"cath_id":"2.30.42.10","chopping":"720-810","consensus_level":"high","plddt":86.7968,"start":720,"end":810},{"cath_id":"2.30.42.10","chopping":"851-936","consensus_level":"high","plddt":85.2843,"start":851,"end":936},{"cath_id":"2.30.42.10","chopping":"1021-1101","consensus_level":"high","plddt":91.0327,"start":1021,"end":1101}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q5TCQ9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q5TCQ9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q5TCQ9-F1-predicted_aligned_error_v6.png","plddt_mean":59.22},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MAGI3","jax_strain_url":"https://www.jax.org/strain/search?query=MAGI3"},"sequence":{"accession":"Q5TCQ9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q5TCQ9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q5TCQ9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q5TCQ9"}},"corpus_meta":[{"pmid":"10748157","id":"PMC_10748157","title":"Interaction of the tumor suppressor PTEN/MMAC with a PDZ domain of MAGI3, a novel membrane-associated guanylate kinase.","date":"2000","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/10748157","citation_count":232,"is_preprint":false},{"pmid":"12140759","id":"PMC_12140759","title":"Oncogenic human papillomavirus E6 proteins target the MAGI-2 and MAGI-3 proteins for degradation.","date":"2002","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/12140759","citation_count":166,"is_preprint":false},{"pmid":"12615970","id":"PMC_12615970","title":"Junctional protein MAGI-3 interacts with receptor tyrosine phosphatase beta (RPTP beta) and tyrosine-phosphorylated proteins.","date":"2003","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/12615970","citation_count":61,"is_preprint":false},{"pmid":"15195140","id":"PMC_15195140","title":"MAGI-3 is involved in the regulation of the JNK signaling pathway as a scaffold protein for frizzled and Ltap.","date":"2004","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/15195140","citation_count":58,"is_preprint":false},{"pmid":"21134377","id":"PMC_21134377","title":"MAGI-3 competes with NHERF-2 to negatively regulate LPA2 receptor signaling in colon cancer cells.","date":"2010","source":"Gastroenterology","url":"https://pubmed.ncbi.nlm.nih.gov/21134377","citation_count":53,"is_preprint":false},{"pmid":"16904289","id":"PMC_16904289","title":"MAGI-3 regulates LPA-induced activation of Erk and RhoA.","date":"2006","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/16904289","citation_count":45,"is_preprint":false},{"pmid":"15003862","id":"PMC_15003862","title":"Human T-cell leukemia virus type 1 Tax oncoprotein induces and interacts with a multi-PDZ domain protein, MAGI-3.","date":"2004","source":"Virology","url":"https://pubmed.ncbi.nlm.nih.gov/15003862","citation_count":40,"is_preprint":false},{"pmid":"35864508","id":"PMC_35864508","title":"E3 ubiquitin ligase MAGI3 degrades c-Myc and acts as a predictor for chemotherapy response in colorectal cancer.","date":"2022","source":"Molecular cancer","url":"https://pubmed.ncbi.nlm.nih.gov/35864508","citation_count":39,"is_preprint":false},{"pmid":"26452219","id":"PMC_26452219","title":"MAGI3 negatively regulates Wnt/β-catenin signaling and suppresses malignant phenotypes of glioma cells.","date":"2015","source":"Oncotarget","url":"https://pubmed.ncbi.nlm.nih.gov/26452219","citation_count":34,"is_preprint":false},{"pmid":"15652357","id":"PMC_15652357","title":"Identification of MAGI-3 as a transforming growth factor-alpha tail binding protein.","date":"2005","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/15652357","citation_count":28,"is_preprint":false},{"pmid":"27205883","id":"PMC_27205883","title":"Premature polyadenylation of MAGI3 produces a dominantly-acting oncogene in human breast cancer.","date":"2016","source":"eLife","url":"https://pubmed.ncbi.nlm.nih.gov/27205883","citation_count":27,"is_preprint":false},{"pmid":"20353789","id":"PMC_20353789","title":"Beta-2 adrenergic receptor mediated ERK activation is regulated by interaction with MAGI-3.","date":"2010","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/20353789","citation_count":24,"is_preprint":false},{"pmid":"29362392","id":"PMC_29362392","title":"Premature polyadenylation of MAGI3 is associated with diminished N6-methyladenosine in its large internal exon.","date":"2018","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/29362392","citation_count":20,"is_preprint":false},{"pmid":"32080912","id":"PMC_32080912","title":"Integrated analyses identify miR-34c-3p/MAGI3 axis for the Warburg metabolism in hepatocellular carcinoma.","date":"2020","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/32080912","citation_count":19,"is_preprint":false},{"pmid":"26248734","id":"PMC_26248734","title":"MAGI3 Suppresses Glioma Cell Proliferation via Upregulation of PTEN Expression.","date":"2015","source":"Biomedical and environmental sciences : BES","url":"https://pubmed.ncbi.nlm.nih.gov/26248734","citation_count":18,"is_preprint":false},{"pmid":"18518978","id":"PMC_18518978","title":"Comparison of p53 and the PDZ domain containing protein MAGI-3 regulation by the E6 protein from high-risk human papillomaviruses.","date":"2008","source":"Virology journal","url":"https://pubmed.ncbi.nlm.nih.gov/18518978","citation_count":14,"is_preprint":false},{"pmid":"34510826","id":"PMC_34510826","title":"Reduced MAGI3 level by HPV18E6 contributes to Wnt/β-catenin signaling activation and cervical cancer progression.","date":"2021","source":"FEBS open bio","url":"https://pubmed.ncbi.nlm.nih.gov/34510826","citation_count":10,"is_preprint":false},{"pmid":"34017581","id":"PMC_34017581","title":"Knockdown of lncRNA RMST protect against myocardial infarction through regulating miR-5692 and MAGI3 axis.","date":"2021","source":"American journal of translational research","url":"https://pubmed.ncbi.nlm.nih.gov/34017581","citation_count":8,"is_preprint":false},{"pmid":"34985721","id":"PMC_34985721","title":"MiR-20b-5p contributes to the dysfunction of vascular smooth muscle cells by targeting MAGI3 in hypertension.","date":"2022","source":"Journal of molecular histology","url":"https://pubmed.ncbi.nlm.nih.gov/34985721","citation_count":7,"is_preprint":false},{"pmid":"41428939","id":"PMC_41428939","title":"YTHDC1-Mediated m6A Modification of MAGI3 mRNA Regulates Proliferation and Differentiation of Myoblasts.","date":"2025","source":"Journal of agricultural and food chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/41428939","citation_count":0,"is_preprint":false},{"pmid":"41876458","id":"PMC_41876458","title":"MAGI3 deficiency unleashes β-catenin conformational change to drive metastatic progression and mTOR inhibitor resistance in ccRCC.","date":"2026","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/41876458","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":12334,"output_tokens":4494,"usd":0.052206,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12553,"output_tokens":4193,"usd":0.083795,"stage2_stop_reason":"end_turn"},"total_usd":0.136001,"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\": 2000,\n      \"finding\": \"MAGI3 localizes to epithelial cell tight junctions and its PDZ domain directly binds the PDZ-binding motif of the tumor suppressor PTEN/MMAC. MAGI3 and PTEN cooperate to modulate AKT/PKB kinase activity, suggesting MAGI3 scaffolds PTEN to phospholipid signaling pathways.\",\n      \"method\": \"Co-immunoprecipitation, pulldown, subcellular localization (tight junction), functional AKT kinase assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal binding assays combined with functional AKT kinase readout; foundational paper replicated by multiple downstream studies\",\n      \"pmids\": [\"10748157\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"High-risk HPV E6 oncoproteins target MAGI-3 for proteasome-mediated degradation via a specific PDZ domain interaction; overexpression of that PDZ domain alone protects full-length MAGI-3 from E6-mediated degradation.\",\n      \"method\": \"Co-expression degradation assays, dominant-negative PDZ domain competition, proteasome inhibitor experiments\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — mechanistic rescue experiment with PDZ domain fragment plus proteasome inhibition, replicated across MAGI-2 and MAGI-3 and confirmed in independent study (PMID:18518978)\",\n      \"pmids\": [\"12140759\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"MAGI-3 interacts with the cytoplasmic region of receptor protein tyrosine phosphatase beta (RPTPβ) via PDZ domains. MAGI-3 localizes to tight junctions (with ZO-1 and cingulin) in epithelial cells, to E-cadherin contacts and focal adhesions in astrocytes, and is also found in the nucleus. MAGI-3 associates with tyrosine-phosphorylated substrates of RPTPβ (a 130 kDa protein in glioblastoma cells, 90 kDa in Caco2), and the RPTPβ–MAGI-3 interaction is required for efficient dephosphorylation of p130 by RPTPβ.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation, pulldown, immunofluorescence, immunoelectron microscopy, vanadate treatment, phosphatase substrate assay\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (Y2H, Co-IP, pulldown, localization, phosphatase activity) in a single focused study\",\n      \"pmids\": [\"12615970\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"MAGI-3 acts as a scaffold protein that specifically binds frizzled-4 and frizzled-7 (but not other frizzleds) via their PDZ-binding motifs, and also binds Ltap (mouse homolog of Drosophila strabismus). These three molecules form a ternary complex that colocalizes at epithelial cell contact sites. MAGI-3 strongly activates JNK in conjunction with frizzled-4 and Ltap, and this activation requires the small GTPase Rac.\",\n      \"method\": \"Co-immunoprecipitation, pulldown, colocalization (immunofluorescence), JNK activation assay, dominant-negative Rac experiment\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ternary complex formation confirmed by Co-IP plus functional JNK assay with Rac dependence in a single focused study\",\n      \"pmids\": [\"15195140\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"HTLV-1 Tax1 (but not Tax2) physically interacts with MAGI-3 in a PDZ-binding motif-dependent manner. This interaction alters the subcellular localization of both Tax1 and MAGI-3, and correlates with the higher transforming activity of Tax1 relative to Tax2.\",\n      \"method\": \"Differential display, RT-PCR, co-immunoprecipitation, subcellular localization (immunofluorescence), transformation assay\",\n      \"journal\": \"Virology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP and localization change demonstrated but mechanistic link to transformation is correlative; single lab\",\n      \"pmids\": [\"15003862\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"MAGI-3 binds to the PDZ-recognition motif (TVV) at the C-terminus of pro-TGFα via its PDZ-1 domain (but not MAGI-1's PDZ-1). MAGI-3 forms a stable complex with membrane-fixed TGFα early in the secretory pathway, and overexpression of MAGI-3 increases TGFα levels in the basolateral medium of polarized MDCK cells, indicating a role in basolateral trafficking of TGFα.\",\n      \"method\": \"Yeast two-hybrid, in vitro PDZ domain binding assay, co-immunoprecipitation, co-localization (immunofluorescence), polarized secretion assay (MDCK cells)\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Y2H, in vitro binding, Co-IP, and functional trafficking assay, single lab\",\n      \"pmids\": [\"15652357\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"MAGI-3 specifically interacts with LPA2 receptor (but not LPA1 or LPA3) via its fifth PDZ domain binding the C-terminal four amino acids of LPA2; mutation of these residues abolishes binding. MAGI-3 is required for LPA-induced ERK activation (silencing inhibits ERK activation) and overexpression of MAGI-3 stimulates LPA-induced RhoA activation.\",\n      \"method\": \"PDZ domain proteomic array screen, co-affinity purification, siRNA knockdown, ERK/RhoA activation assays, mutational analysis of LPA2 C-terminus\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — binding confirmed biochemically with mutational validation plus functional signaling readouts (ERK, RhoA) using both OE and KD; single lab\",\n      \"pmids\": [\"16904289\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"HPV E6-mediated degradation of MAGI-3 is mechanistically distinct from E6-mediated p53 degradation: proteasome inhibition does not protect MAGI-3 (unlike p53), and MAGI-3 is not ubiquitinated by E6 under conditions where p53 is ubiquitinated by E6/MDM2.\",\n      \"method\": \"Proteasome inhibitor assays, in vivo ubiquitination assay\",\n      \"journal\": \"Virology journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — parallel mechanistic comparison with two orthogonal assays (proteasome inhibition, ubiquitination); single lab\",\n      \"pmids\": [\"18518978\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"MAGI-3 binds β2-adrenergic receptor (β2AR) constitutively via the fifth PDZ domain interacting with the C-terminal DSLL motif of the receptor; agonist stimulation enhances the interaction. MAGI-3 expression substantially retards β2AR-stimulated ERK1/2 activation.\",\n      \"method\": \"Co-immunoprecipitation, PDZ domain binding assay, ERK activation assay with MAGI-3 overexpression\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP and functional ERK assay; single lab, single study\",\n      \"pmids\": [\"20353789\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"MAGI-3 competes with NHERF-2 for binding to LPA2 receptor and phospholipase C-β3. MAGI-3 increases LPA2–Gα12 coupling while NHERF-2 promotes LPA2–Gαq coupling, and MAGI-3 acts as a negative regulator of LPA2-induced phospholipase C activity, cell migration, invasion, NF-κB activation, and JNK activity.\",\n      \"method\": \"Overexpression and siRNA knockdown, co-immunoprecipitation, phospholipase C (inositol phosphate) assay, NF-κB reporter assay, migration/invasion assays\",\n      \"journal\": \"Gastroenterology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal functional assays with both OE and KD plus G-protein coupling analysis; single lab\",\n      \"pmids\": [\"21134377\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"MAGI3 overexpression in glioma cells upregulates PTEN protein expression, inhibits Akt phosphorylation, and suppresses proliferation; MAGI3 loss downregulates PTEN, activating the PI3K/Akt pathway.\",\n      \"method\": \"Stable transfection (overexpression), Western blot, xenograft tumor growth assay, GSEA of GEO dataset\",\n      \"journal\": \"Biomedical and environmental sciences : BES\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — functional OE with mechanistic western blot readout and in vivo xenograft; single lab, single method per endpoint\",\n      \"pmids\": [\"26248734\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"MAGI3 directly binds β-catenin through its PDZ domains interacting with the PDZ-binding motif of β-catenin. MAGI3 overexpression inhibits β-catenin transcriptional activity and suppresses expression of β-catenin target genes (Cyclin D1, Axin2); MAGI3 knockdown enhances their expression. This inhibits glioma cell proliferation, migration, and cell cycle progression.\",\n      \"method\": \"GST pulldown, co-immunoprecipitation, β-catenin luciferase reporter assay, Western blot, overexpression and knockdown, xenograft tumor assay\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding confirmed by GST pulldown and Co-IP, functional transcriptional reporter, and in vivo xenograft; single lab, multiple orthogonal methods\",\n      \"pmids\": [\"26452219\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Premature cleavage and polyadenylation of MAGI3 produces a truncated protein isoform (MAGI3-pPA) that acts in a dominant-negative manner to prevent full-length MAGI3 from interacting with the YAP oncoprotein, thereby relieving YAP inhibition and promoting malignant transformation of human mammary epithelial cells.\",\n      \"method\": \"RNA isoform identification, dominant-negative overexpression, co-immunoprecipitation (full-length MAGI3–YAP interaction), transformation assay in mammary epithelial cells\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP showing disruption of MAGI3–YAP interaction combined with functional transformation assay; single lab, two orthogonal approaches\",\n      \"pmids\": [\"27205883\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MAGI3 physically interacts with β-catenin to regulate its transcriptional activity and c-Myc expression, which controls glycolytic gene expression (HK2, PFKL, LDHA) and the Warburg effect in hepatocellular carcinoma cells.\",\n      \"method\": \"Co-immunoprecipitation, β-catenin transcriptional activity assay, glycolysis functional assays (ECAR, lactate production, glucose consumption), Western blot\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP plus functional glycolysis readouts; single lab, confirmation of existing β-catenin interaction mechanism\",\n      \"pmids\": [\"32080912\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"HPV18 E6 reduces MAGI3 protein levels, activating Wnt/β-catenin signaling and promoting cervical cancer cell migration and invasion via increased β-catenin levels; MAGI3 itself inhibits β-catenin levels and suppresses migration/invasion.\",\n      \"method\": \"Knockdown and overexpression of MAGI3, E6 expression, Western blot for β-catenin, migration/invasion assays\",\n      \"journal\": \"FEBS open bio\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — functional KD/OE with mechanistic signaling readout; single lab, single study\",\n      \"pmids\": [\"34510826\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"MAGI3 functions as a novel substrate-recognition subunit of a SKP1-Cullin E3 ubiquitin ligase complex that binds c-Myc and promotes its ubiquitination and proteasomal degradation, thereby inhibiting CRC cell growth and promoting chemosensitivity.\",\n      \"method\": \"Co-immunoprecipitation, GST pulldown, ubiquitination assay, Western blot, cell proliferation/apoptosis assays, xenograft assay\",\n      \"journal\": \"Molecular cancer\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — direct ubiquitination assay, GST pulldown, Co-IP plus in vitro and in vivo functional validation; single lab, multiple orthogonal methods\",\n      \"pmids\": [\"35864508\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"MAGI3 binds the C-terminus of β-catenin via its PDZ domains and disrupts intramolecular N-terminus–ARM domain interactions within β-catenin, thereby exposing phosphorylation sites and enabling GSK-3β-mediated phosphorylation and ubiquitin-dependent degradation of β-catenin. Loss of MAGI3 hyperactivates β-catenin and drives mTOR inhibitor resistance in ccRCC.\",\n      \"method\": \"Multi-omics analysis, co-immunoprecipitation, PDZ domain binding assays, phosphorylation and ubiquitination assays, invasion/migration assays, in vivo metastasis assay, drug resistance assay\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — Co-IP and functional assays with mechanistic model of conformational change; single lab, novel conformational mechanism not yet independently replicated\",\n      \"pmids\": [\"41876458\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MAGI3 is a multi-PDZ/WW domain scaffold protein that localizes to tight junctions and cell–cell contacts, where it suppresses oncogenic signaling through several mechanisms: it directly binds PTEN via a PDZ interaction to modulate AKT activity; it binds β-catenin via PDZ domains to promote GSK-3β-mediated phosphorylation and ubiquitin-dependent degradation of β-catenin, suppressing Wnt target gene expression; it acts as a substrate-recognition subunit of a SKP1-Cullin E3 ligase to ubiquitinate and degrade c-Myc; it scaffolds RPTPβ with its substrates at the plasma membrane; it organizes frizzled-4/Ltap complexes to activate JNK via Rac; it negatively regulates LPA2-, β2AR-, and frizzled-mediated signaling by competing with pro-oncogenic PDZ proteins; and it is itself targeted for degradation by HPV E6 oncoproteins (via a non-ubiquitin-dependent proteasomal route) and by premature polyadenylation that generates a dominant-negative truncated isoform which prevents full-length MAGI3 from restraining YAP activity.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"MAGI3 is a multi-PDZ/WW domain scaffold protein at epithelial tight junctions and cell\\u2013cell contacts that restrains multiple oncogenic signaling pathways by physically organizing receptors, phosphatases, and signaling effectors at the membrane [#0, #2]. Through its PDZ domains it directly binds the tumor suppressor PTEN to modulate AKT/PKB activity, and MAGI3 levels positively control PTEN protein and suppress PI3K/Akt signaling and proliferation [#0, #10]. A central tumor-suppressive function is the negative regulation of \\u03b2-catenin: MAGI3 binds the C-terminal PDZ-binding motif of \\u03b2-catenin, disrupting its intramolecular N-terminus\\u2013ARM interaction to expose phosphorylation sites, enabling GSK-3\\u03b2-mediated phosphorylation and ubiquitin-dependent degradation, thereby suppressing \\u03b2-catenin transcriptional output (Cyclin D1, Axin2, c-Myc) and downstream programs including the Warburg effect [#11, #13, #16]. MAGI3 also acts as the substrate-recognition subunit of a SKP1-Cullin E3 ubiquitin ligase that ubiquitinates c-Myc for proteasomal degradation [#15]. As a PDZ scaffold it engages numerous transmembrane partners\\u2014RPTP\\u03b2 and its tyrosine-phosphorylated substrates [#2], frizzled-4/-7 and Ltap to activate JNK through Rac [#3], LPA2 and \\u03b22-adrenergic receptors where it competes with pro-oncogenic PDZ proteins such as NHERF-2 to bias G-protein coupling and dampen ERK/RhoA/PLC signaling [#6, #8, #9], and pro-TGF\\u03b1 for basolateral trafficking [#5]. MAGI3's growth-restraining activity is antagonized by viral oncoproteins (HPV E6 drives its proteasomal degradation by a ubiquitin-independent route; HTLV-1 Tax1 mislocalizes it) and by premature cleavage/polyadenylation that yields a dominant-negative truncated isoform releasing YAP from inhibition [#1, #7, #4, #12, #14].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Established MAGI3 as a tight-junction scaffold that physically tethers the tumor suppressor PTEN to modulate AKT signaling, defining its first growth-regulatory function.\",\n      \"evidence\": \"Co-IP, pulldown, tight-junction localization, and AKT kinase assay in epithelial cells\",\n      \"pmids\": [\"10748157\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not establish stoichiometry or whether PTEN catalytic regulation is direct\", \"No in vivo phenotype for the MAGI3\\u2013PTEN axis\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Showed MAGI3 is a target of high-risk HPV E6 oncoproteins, framing its degradation as part of viral transformation and implying a tumor-suppressive role.\",\n      \"evidence\": \"Co-expression degradation assays with dominant-negative PDZ competition and proteasome inhibition\",\n      \"pmids\": [\"12140759\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of degradation not resolved here\", \"Endogenous consequence of MAGI3 loss not measured\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Defined MAGI3 as a PDZ scaffold for receptor tyrosine phosphatase RPTP\\u03b2 required for efficient substrate dephosphorylation, broadening its role to organizing phosphatase\\u2013substrate complexes.\",\n      \"evidence\": \"Y2H, Co-IP, pulldown, immuno-EM localization, and phosphatase substrate assay in glioblastoma and Caco2 cells\",\n      \"pmids\": [\"12615970\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the 130/90 kDa substrates not determined\", \"Functional consequence of altered substrate phosphorylation unclear\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Demonstrated MAGI3 nucleates a frizzled-4/-7\\u2013Ltap ternary complex that activates JNK via Rac, and that HTLV-1 Tax1 binds and relocalizes MAGI3, linking the scaffold to planar/non-canonical Wnt signaling and viral transformation.\",\n      \"evidence\": \"Co-IP, colocalization, JNK activation with dominant-negative Rac; differential display and transformation assay for Tax1\",\n      \"pmids\": [\"15195140\", \"15003862\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Tax1\\u2013transformation link is correlative\", \"Physiological context for frizzled-driven JNK activation not defined\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identified MAGI3 as a selective LPA2-receptor partner required for LPA-induced ERK and RhoA signaling, showing the scaffold can both promote and restrain receptor outputs depending on context.\",\n      \"evidence\": \"PDZ proteomic array, co-affinity purification, LPA2 C-terminal mutagenesis, siRNA, ERK/RhoA assays\",\n      \"pmids\": [\"16904289\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not reconcile positive ERK/RhoA role with later negative regulatory findings\", \"Downstream cellular phenotype not assessed\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Resolved the mechanism of HPV E6-mediated MAGI3 loss as ubiquitin-independent and proteasome-resistant, mechanistically distinguishing it from E6/MDM2-driven p53 degradation.\",\n      \"evidence\": \"Proteasome inhibitor and in vivo ubiquitination assays comparing MAGI3 and p53\",\n      \"pmids\": [\"18518978\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The actual proteolytic route remains undefined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Established MAGI3 as a negative regulator of GPCR signaling that biases G-protein coupling by competing with NHERF-2 at LPA2 and binds \\u03b22AR, dampening ERK, PLC, NF-\\u03baB, migration and invasion.\",\n      \"evidence\": \"Co-IP, PDZ binding assays, inositol phosphate/NF-\\u03baB reporter, migration/invasion assays with OE and KD\",\n      \"pmids\": [\"21134377\", \"20353789\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How MAGI3 selects G\\u03b112 vs G\\u03b1q coupling structurally is unknown\", \"Relationship to its earlier positive ERK role at LPA2 unresolved\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Defined MAGI3 as a direct \\u03b2-catenin binder that suppresses Wnt transcriptional output and tumor growth, and confirmed its PTEN/Akt-suppressive role in glioma, consolidating its tumor-suppressor identity.\",\n      \"evidence\": \"GST pulldown, Co-IP, \\u03b2-catenin luciferase reporter, OE/KD, and xenograft assays in glioma\",\n      \"pmids\": [\"26452219\", \"26248734\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not specify how MAGI3 binding promotes \\u03b2-catenin degradation\", \"Endogenous-level requirement in normal tissue untested\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Revealed a regulatory mechanism by which premature cleavage/polyadenylation generates a dominant-negative MAGI3 isoform that blocks the full-length protein from inhibiting YAP, promoting transformation.\",\n      \"evidence\": \"RNA isoform identification, dominant-negative OE, MAGI3\\u2013YAP Co-IP, and transformation assay in mammary epithelial cells\",\n      \"pmids\": [\"27205883\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The MAGI3\\u2013YAP binding interface not mapped\", \"Prevalence of the truncated isoform in primary tumors not quantified\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Showed MAGI3 itself functions as a substrate-recognition subunit of a SKP1-Cullin E3 ligase that ubiquitinates c-Myc for degradation, adding an enzymatic adaptor role beyond passive scaffolding.\",\n      \"evidence\": \"Co-IP, GST pulldown, ubiquitination assay, proliferation/apoptosis and xenograft assays in colorectal cancer\",\n      \"pmids\": [\"35864508\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The specific Cullin/F-box partners were not fully defined\", \"How this E3 role integrates with \\u03b2-catenin-mediated c-Myc control is unclear\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Provided a structural mechanism for \\u03b2-catenin regulation: MAGI3 binding disrupts \\u03b2-catenin's intramolecular N-terminus\\u2013ARM interaction to expose GSK-3\\u03b2 phosphorylation sites and license its degradation, with loss driving mTOR-inhibitor resistance.\",\n      \"evidence\": \"Multi-omics, Co-IP, PDZ binding, phosphorylation/ubiquitination assays, metastasis and drug-resistance assays in ccRCC\",\n      \"pmids\": [\"41876458\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Conformational model not yet independently replicated\", \"No direct structural data for the proposed \\u03b2-catenin conformational change\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How MAGI3's distinct activities\\u2014PDZ scaffolding, E3 ligase adaptor function, and conformational regulation of \\u03b2-catenin\\u2014are coordinated and selected in different tissues remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of full-length MAGI3 multivalent assembly\", \"Tissue-specific partner selection rules undefined\", \"No germline loss-of-function disease association established in the corpus\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 2, 3, 6, 9]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [9, 11, 16]},\n      {\"term_id\": \"GO:0016874\", \"supporting_discovery_ids\": [15]},\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [15]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 2, 6, 8]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 3, 6, 9, 11]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [15, 16]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [1, 12, 14]}\n    ],\n    \"complexes\": [\"SKP1-Cullin E3 ubiquitin ligase\", \"frizzled-4/Ltap ternary complex\"],\n    \"partners\": [\"PTEN\", \"CTNNB1\", \"MYC\", \"PTPRB\", \"FZD4\", \"LPAR2\", \"ADRB2\", \"YAP1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}