Affinage

MDGA1

MAM domain-containing glycosylphosphatidylinositol anchor protein 1 · UniProt Q8NFP4

Length
955 aa
Mass
105.8 kDa
Annotated
2026-06-10
26 papers in source corpus 17 papers cited in narrative 17 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 7/8 claims corpus-supported (88%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

MDGA1 is a GPI-anchored, lipid-raft-localized cell-surface glycoprotein of the immunoglobulin/MAM-domain family that governs cortical neuron migration and the balance of inhibitory versus excitatory synaptic connectivity in the brain (PMID:15922729, PMID:16641224, PMID:29281813). During corticogenesis it acts cell-autonomously to direct radial migration of superficial-layer neurons (PMID:16641224) and supports basal progenitor proliferation in the subventricular zone in a complex with Connexin43 (PMID:26776515). At the synapse, MDGA1 forms a direct cis complex with neuroligin-2: crystal and structural studies show its Ig1-Ig2 region binds the neuroligin-2 dimer at the same surface used by neurexins, sterically occluding neurexin access and thereby suppressing trans-synaptic bridge formation and GABAergic synaptogenesis (PMID:28641112, PMID:28641111). This negative regulation depends on the global 3D conformation of the entire MDGA1 ectodomain rather than ectodomain binding affinity alone (PMID:36889589). Consistent with this mechanism, MDGA1 loss elevates hippocampal CA1 perisomatic inhibitory synapse density and transmission, impairs LTP, and produces learning and memory deficits (PMID:29281813), and MDGA1 deletion is epistatic to and rescues the synaptic and behavioral phenotypes of Nlgn2-null mice (PMID:39284869). A separate MAM-domain interaction with presynaptic APP mediates dendrite-compartment-specific disinhibition at distal CA1 dendrites (PMID:35074912). MDGA1 is cleaved within its juxtamembrane region by the protease BACE1 in vivo, linking its abundance to BACE1 activity (PMID:31908000). Disease-associated missense mutations disrupt either the synapse-regulatory triangular ectodomain conformation or cortical neuron migration, defining distinct loss-of-function mechanisms relevant to autism spectrum disorder (PMID:41862769).

Mechanistic history

Synthesis pass · year-by-year structured walk · 16 steps
  1. 2005 Medium

    Establishing how MDGA1 is displayed at the cell surface was the first step toward understanding its function; it was shown to be a GPI-anchored, raft-enriched, N-glycosylated plasma membrane protein.

    Evidence PI-PLC cleavage, sucrose density lipid-raft fractionation, and glycosylation assays on human MDGA1

    PMID:15922729

    Open questions at the time
    • Does not address binding partners or signaling role
    • Single lab, non-neuronal biochemical characterization
  2. 2006 High

    Whether MDGA1 has a developmental role was unknown; loss-of-function in vivo showed it is required cell-autonomously for radial migration of superficial cortical neurons.

    Evidence In utero RNAi electroporation with rat-MDGA1 rescue control

    PMID:16641224

    Open questions at the time
    • Molecular partners driving migration not identified
    • Does not connect migration to later synaptic functions
  3. 2006 Medium

    To define candidate binding modalities, domain-deletion binding assays mapped distinct heterophilic partners to the MAM domain (axon-rich regions) and the Ig domains (differentiating muscle).

    Evidence Truncated MDGA1 constructs applied to developing nervous-system tissue sections

    PMID:16782075

    Open questions at the time
    • Molecular identity of the binding partners not determined
    • Functional consequence of binding not tested
  4. 2010 Medium

    The adhesion/motility properties of MDGA1 were probed in epithelial cells, assigning Ig-domain control of motility and ECM (collagen IV) adhesion and MAM-domain control of heterophilic cell-cell adhesion.

    Evidence Stable over- and truncated expression plus siRNA in MDCK cells with migration/adhesion assays

    PMID:21505559

    Open questions at the time
    • Non-neuronal system; relevance to brain function unclear
    • Direct molecular adhesion partners not identified
  5. 2016 Medium

    The neurogenic role of MDGA1 was extended to progenitors; it forms a complex with Connexin43 and is required for basal progenitor proliferation and correct positioning.

    Evidence Conditional knockout plus co-IP/co-localization and histology in the cortical SVZ

    PMID:26776515

    Open questions at the time
    • Mechanism by which the MDGA1-Cx43 complex controls proliferation unresolved
    • Single lab
  6. 2017 High

    The central molecular mechanism — how MDGA1 suppresses inhibitory synapses — was solved structurally: it binds the neuroligin-2 dimer via Ig domains at the neurexin-binding surface, sterically blocking neurexin and inhibiting synaptogenic bridging.

    Evidence Two concurrent crystal structures of MDGA1 Ig domains with NLGN2, structure-guided mutagenesis, binding affinity, cell-based synaptogenesis assays

    PMID:28641111 PMID:28641112

    Open questions at the time
    • In vitro affinity similar for NLGN1 and NLGN2 but in vivo selectivity for NLGN2 not mechanistically explained
    • Does not establish in vivo synaptic phenotype
  7. 2017 High

    Whether the in vitro steric mechanism operates in the brain was tested; germline knockout selectively elevated perisomatic inhibitory synapses and transmission and impaired LTP, learning, and memory.

    Evidence Germline KO mouse with electrophysiology, immunohistochemistry, and behavioral testing

    PMID:29281813

    Open questions at the time
    • Excitatory synapses reported unaffected — later contradicted
    • Subcellular basis of perisomatic selectivity not fully resolved
  8. 2019 High

    How MDGA1 abundance is post-translationally controlled was addressed: it is an in vivo BACE1 substrate cleaved in its juxtamembrane domain, linking MDGA1 levels to BACE1 activity.

    Evidence Quantitative proteomics of BACE1 KO vs WT brain, immunoblot validation, and BACE1 inhibitor treatment in neurons

    PMID:31908000

    Open questions at the time
    • Functional consequence of cleavage on synaptic regulation not directly demonstrated
    • Whether cleavage releases a signaling fragment unknown
  9. 2022 High

    A second trans-synaptic mechanism was uncovered: the MAM domain binds presynaptic APP to mediate compartment-specific disinhibition at distal CA1 dendrites.

    Evidence Reciprocal co-IP with domain mapping, domain-deletion/overexpression, electrophysiology, protein infusion, and behavior

    PMID:35074912

    Open questions at the time
    • How APP and NLGN2 pathways are spatially segregated within a neuron not fully resolved
    • Single lab
  10. 2023 High

    The structural determinant of function was refined: the global 3D ectodomain conformation (compact vs extended), not soluble affinity, is required to conceal NLGN2 and suppress synaptogenesis.

    Evidence Cryo-EM single-particle conformational analysis with designer elbow mutants and cell-based assays

    PMID:36889589

    Open questions at the time
    • How conformation is regulated in vivo unknown
    • Conformational states not visualized at the membrane
  11. 2023 Medium

    Endogenous targeting and the inhibitory-synapse model were challenged: epitope-tagged knock-in revealed enrichment at excitatory synapses and a cell-autonomous requirement for AMPA-receptor transmission without affecting GABAergic transmission.

    Evidence Epitope-tagged knock-in mice, shRNA, CRISPR/Cas9 KO, slice electrophysiology (preprint)

    PMID:37720016

    Open questions at the time
    • Preprint, not peer-reviewed
    • Directly contradicts prior inhibitory-synapse findings — reconciliation unresolved
  12. 2023 Medium

    A pathological context for MDGA1's scaffolding role emerged: after nerve injury its upregulation shifts neuroligin-2 from inhibitory toward excitatory scaffolding to drive pain hypersensitivity.

    Evidence In vivo siRNA, co-IP, synaptosomal fractionation, Western blot, and behavioral pain testing after spinal nerve ligation

    PMID:37955815

    Open questions at the time
    • Molecular mechanism of the inhibitory-to-excitatory scaffold switch not defined
    • Single lab
  13. 2024 Medium

    Genetic epistasis was established in vivo: MDGA1 deletion rescues gephyrin aggregation, inhibitory transmission, and anxiety phenotypes of Nlgn2 KO mice, confirming MDGA1 acts on the NLGN2 pathway at GABAergic synapses.

    Evidence Nlgn2 KO x Mdga1 KO double knockout with electrophysiology, gephyrin immunostaining, behavior

    PMID:39284869

    Open questions at the time
    • Layer-specific effects of combined deletion not mechanistically explained
    • Single lab
  14. 2025 Medium

    The MDGA1-NLGN2 axis was shown to operate in a circuit relevant to mood, with stress-regulated interaction in the lateral habenula and MDGA1 loss conferring resistance to stress-induced depressive behavior.

    Evidence Co-IP, viral conditional KO, Nlgn2 binding-deficient knock-in, electrophysiology, immunostaining, behavior

    PMID:39897557

    Open questions at the time
    • Upstream signal driving stress-induced interaction increase unknown
    • Single lab
  15. 2025 Medium

    Disease relevance was tied directly to mechanism: distinct ASD-associated missense pairs cause loss of function either by disrupting the triangular ectodomain conformation (loss of GABAergic synapse regulation) or by altering cortical migration.

    Evidence In utero overexpression, knock-in mice, structural analysis, electrophysiology, behavioral testing

    PMID:41862769

    Open questions at the time
    • Patient-level genetic causality not established by these models
    • Single lab
  16. 2026 Medium

    The strength of MDGA1's hippocampal synaptic regulation was re-examined; endogenous protein was dendritic without clear synaptic enrichment and acute deletion did not alter transmission, indicating its synaptic role may be transient in young mice.

    Evidence Epitope-tagged knock-in mice, acute conditional deletion, slice electrophysiology, immunofluorescence

    PMID:41530055

    Open questions at the time
    • Discrepancy with germline-KO phenotypes (developmental vs acute) unresolved
    • Age- and circuit-dependence of function not mapped

Open questions

Synthesis pass · forward-looking unresolved questions
  • It remains unresolved whether MDGA1 predominantly restrains inhibitory synapses (via NLGN2 steric blockade) or shapes excitatory transmission, and how developmental versus acute requirements and tagging/deletion strategies account for the conflicting endogenous-localization and phenotype data.
  • Excitatory vs inhibitory primacy unreconciled across labs
  • Developmental versus acute requirement undefined
  • In vivo regulation of ectodomain conformation and BACE1 cleavage on synaptic output unknown

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098772 molecular function regulator activity 3 GO:0098631 cell adhesion mediator activity 2 GO:0140313 molecular sequestering activity 2
Localization
GO:0005886 plasma membrane 2
Pathway
R-HSA-112316 Neuronal System 4 R-HSA-1500931 Cell-Cell communication 3 R-HSA-1266738 Developmental Biology 2
Partners
APPBACE1GJA1NLGN2NRXN1

Evidence

Reading pass · 17 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2017 Crystal structure of MDGA1 Ig1-Ig2 in complex with NLGN2 reveals that two MDGA1 molecules each span the entire NLGN2 dimer; MDGA1 Ig1 binds the same region on NLGN2 as neurexins do, establishing that MDGA1 sterically blocks neurexin access to neuroligin-2, thereby inhibiting trans-synaptic bridge formation. Crystal structure determination + site-directed mutagenesis + binding affinity measurements Neuron High 28641112
2017 Crystal structure of human NL2/MDGA1 Ig1-3 complex reveals a stable 2:2 arrangement with three interaction interfaces; cell-based assays with structure-guided mutants show all three contact patches are required for MDGA1's negative regulation of NL2-mediated synaptogenic activity. MDGA1 Ig1 competes with neurexins for NL2. Despite similar binding affinities to NL1 and NL2 in vitro, MDGA1 selectively associates with NL2 but not NL1 in vivo. Crystal structure determination + cell-based synaptogenesis assays + site-directed mutagenesis + binding affinity measurements + co-immunoprecipitation Neuron High 28641111
2023 MDGA1 ectodomain can adopt both compact and extended 3D conformations that both bind NLGN2; designer mutants at strategic molecular elbows alter the distribution of 3D conformations without changing soluble ectodomain binding affinity to NLGN2, yet in a cellular context these mutants impair NLGN2 binding, reduce capacity to conceal NLGN2 from NRXN1β, and suppress NLGN2-mediated inhibitory presynaptic differentiation — demonstrating that global 3D conformation of the entire MDGA1 ectodomain is required for its function. Cryo-EM/single-particle analysis of conformational states + designer mutagenesis + cell-based functional assays The Journal of biological chemistry High 36889589
2006 RNAi-mediated knockdown of MDGA1 in vivo blocks proper radial migration of superficial layer (2/3) cortical neurons, with transfected cells accumulating deep in the cortical plate; this defect is rescued by co-transfection of rat MDGA1, establishing that MDGA1 acts cell-autonomously to control migration of superficial layer cortical neurons. In utero RNAi electroporation + rescue experiment with rat MDGA1 construct The Journal of neuroscience High 16641224
2016 MDGA1 co-localizes and forms a complex with gap junction protein Connexin43 in basal progenitor cell membranes of the cortical SVZ; conditional deletion of MDGA1 from basal progenitors reduces their proliferation, decreases SVZ size, causes ectopic positioning of basal progenitors in the cortical plate, and reduces production of cortical layer neurons. Conditional knockout (floxed allele) + co-immunoprecipitation/co-localization + histological analysis Cell reports Medium 26776515
2017 Genetic deletion of MDGA1 in vivo elevates hippocampal CA1 inhibitory (but not excitatory) synapse density and transmission, selectively at perisomatic (but not distal dendritic) inhibitory synapses; MDGA1 is selectively expressed by pyramidal neurons. Mdga1-/- mice show muted responses to neural excitation, resistance to induced seizures, impaired hippocampal LTP, and deficits in spatial and context-dependent learning and memory. Germline knockout mouse + electrophysiology + immunohistochemistry + behavioral testing Cell reports High 29281813
2022 The MDGA1 MAM domain directly interacts with the extension domain of amyloid precursor protein (APP); MDGA1-mediated synaptic disinhibition requires the MAM domain and is prominent at distal dendrites of hippocampal CA1 pyramidal neurons. Presynaptic APP in GABAergic interneurons is required for this trans-synaptic mechanism. Overexpression of MDGA1 WT or MAM domain alone (but not MAM-deleted MDGA1) impairs novel object-recognition memory. Co-immunoprecipitation + domain deletion/overexpression + electrophysiology + behavioral testing + protein infusion experiments Proceedings of the National Academy of Sciences of the United States of America High 35074912
2019 MDGA1 is an in vivo substrate of the Alzheimer protease BACE1; BACE1 cleaves MDGA1 within its juxtamembrane domain. Inhibition or deletion of BACE1 in primary neurons and mouse brains results in increased full-length MDGA1 protein levels. Isotope-label quantitative proteomics of BACE1 KO vs. WT mouse brains + immunoblot validation in primary neurons + BACE1 inhibitor treatment FASEB journal High 31908000
2005 Human MDGA1 is a GPI-anchored glycoprotein that localizes to the plasma membrane via the secretory pathway; it is enriched in lipid raft membrane microdomains and undergoes N-glycosylation. GPI anchorage is confirmed by phospholipase C (PI-PLC) cleavage. PI-PLC treatment + sucrose density gradient fractionation for lipid rafts + glycosylation assays Experimental cell research Medium 15922729
2006 MDGA1 interacts heterophilically with axon-rich regions primarily through its MAM domain, and interacts with differentiating muscle through its N-terminal Ig domain region, establishing domain-specific binding partners in the developing nervous system. Domain-deletion binding assays using truncated MDGA1 constructs applied to tissue sections Brain research Medium 16782075
2010 MDGA1 expression increases cell motility and cell-cell adhesion, and decreases adhesion to extracellular matrix proteins (particularly collagen IV) in MDCK cells. Truncation experiments show that Ig domains contribute to motility and collagen IV adhesion reduction, while the MAM domain mediates heterophilic cell-cell adhesion. siRNA silencing of MDGA1 significantly increases adhesion to collagen IV. Stable overexpression of full-length and truncated MDGA1 + siRNA knockdown + cell migration and adhesion assays Cancer microenvironment Medium 21505559
2023 Using epitope-tagged MDGA1 knock-in mice, endogenous MDGA1 was found enriched at excitatory (not inhibitory) synapses. shRNA knockdown and CRISPR/Cas9 knockout of MDGA1 caused cell-autonomous impairment of AMPA receptor-mediated (excitatory) synaptic transmission without affecting GABAergic transmission — contradicting previous reports that MDGA1 primarily suppresses inhibitory synapses. Epitope-tagged knock-in mice + shRNA knockdown + CRISPR/Cas9 KO + slice electrophysiology bioRxivpreprint Medium 37720016
2024 Loss of MDGA1 expression (but not heterozygous MDGA2 deletion) rescues the abnormal cytosolic gephyrin aggregation, reduction in inhibitory synaptic transmission, and exacerbated anxiety behavior in Nlgn2 knockout mice; combined Nlgn2 and MDGA1 deletion causes exacerbated layer-specific loss of gephyrin puncta, demonstrating epistatic interaction between MDGA1 and Nlgn2 at GABAergic synapses in hippocampal CA1. Double knockout (Nlgn2 KO × Mdga1 KO) + electrophysiology + immunostaining for gephyrin + behavioral analysis Communications biology Medium 39284869
2025 MDGA1 and Nlgn2 selectively interact in the lateral habenula (LHb); this interaction is elevated following chronic restrained stress. Germline MDGA1 KO increases inhibitory transmission and GABAergic synapse density in the LHb; introducing an Nlgn2 variant incapable of binding MDGA1 similarly enhances inhibitory transmission and synapse density. MDGA1 deficiency in adult LHb confers resistance to chronic stress-induced depressive behaviors. Co-immunoprecipitation + conditional KO (viral Cre) + Nlgn2 knock-in variant + electrophysiology + immunostaining + behavioral testing Theranostics Medium 39897557
2023 After spinal nerve ligation, MDGA1 is upregulated in the dorsal horn; MDGA1 knockdown with siRNA normalizes increased GluR1 surface delivery in the synaptosomal membrane fraction, reduces pain hypersensitivity, inhibits the increased neuroligin-2/PSD-95 (excitatory) interaction, and prevents decreased neuroligin-2/Gephyrin (inhibitory) interaction — establishing that upregulated MDGA1 shifts neuroligin-2 from inhibitory toward excitatory scaffolding. siRNA knockdown in vivo + co-immunoprecipitation + synaptosomal fractionation + Western blot + behavioral pain testing Neurochemical research Medium 37955815
2025 ASD-associated MDGA1 Tyr635Cys/Glu756Gln double mutation disrupts the triangular extracellular structure of MDGA1 and renders it unable to impact GABAergic synapses in hippocampal CA1 neurons, while MDGA1 Val116Met/Ala688Val overexpression alters cortical neuron migration and impairs ultrasonic vocalizations — demonstrating that different missense pairs cause distinct loss-of-function mechanisms. In utero overexpression + knock-in mouse + electrophysiology + structural analysis + behavioral testing EMBO molecular medicine Medium 41862769
2026 Using epitope-tagged MDGA1 knock-in mice, endogenous MDGA1 in hippocampal CA1 localizes to dendrites but shows no clear enrichment at excitatory or inhibitory synapses; acute pre- or postsynaptic deletion of MDGA1 does not affect inhibitory or excitatory synaptic transmission in slice electrophysiology, suggesting MDGA1 may transiently inhabit but does not strongly regulate hippocampal synapses in young mice. Epitope-tagged knock-in mice + conditional acute deletion + slice electrophysiology + immunofluorescence The Journal of neuroscience Medium 41530055

Source papers

Stage 0 corpus · 26 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2008 Association analysis of schizophrenia on 18 genes involved in neuronal migration: MDGA1 as a new susceptibility gene. American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics 103 18384059
2017 Molecular Mechanism of MDGA1: Regulation of Neuroligin 2:Neurexin Trans-synaptic Bridges. Neuron 62 28641112
2017 Structural Insights into Modulation of Neurexin-Neuroligin Trans-synaptic Adhesion by MDGA1/Neuroligin-2 Complex. Neuron 59 28641111
2006 Radial migration of superficial layer cortical neurons controlled by novel Ig cell adhesion molecule MDGA1. The Journal of neuroscience : the official journal of the Society for Neuroscience 53 16641224
2017 Loss of Synapse Repressor MDGA1 Enhances Perisomatic Inhibition, Confers Resistance to Network Excitation, and Impairs Cognitive Function. Cell reports 49 29281813
2010 The MDGA1 gene confers risk to schizophrenia and bipolar disorder. Schizophrenia research 36 21146959
2006 Novel IgCAM, MDGA1, expressed in unique cortical area- and layer-specific patterns and transiently by distinct forebrain populations of Cajal-Retzius neurons. Cerebral cortex (New York, N.Y. : 1991) 34 16959869
2022 MDGA1 negatively regulates amyloid precursor protein-mediated synapse inhibition in the hippocampus. Proceedings of the National Academy of Sciences of the United States of America 29 35074912
2006 MDGA1, an IgSF molecule containing a MAM domain, heterophilically associates with axon- and muscle-associated binding partners through distinct structural domains. Brain research 28 16782075
2019 Mouse brain proteomics establishes MDGA1 and CACHD1 as in vivo substrates of the Alzheimer protease BACE1. FASEB journal : official publication of the Federation of American Societies for Experimental Biology 21 31908000
2005 Characterization of MDGA1, a novel human glycosylphosphatidylinositol-anchored protein localized in lipid rafts. Experimental cell research 18 15922729
2016 Formation of the Cortical Subventricular Zone Requires MDGA1-Mediated Aggregation of Basal Progenitors. Cell reports 17 26776515
2022 Differential expression of MDGA1 in major depressive disorder. Brain, behavior, & immunity - health 12 36247836
2009 Characterization of teleost Mdga1 using a gene-trap approach in medaka (Oryzias latipes). Genesis (New York, N.Y. : 2000) 12 19422017
2023 Designer molecules of the synaptic organizer MDGA1 reveal 3D conformational control of biological function. The Journal of biological chemistry 11 36889589
2010 Expression of Human MDGA1 Increases Cell Motility and Cell-Cell Adhesion and Reduces Adhesion to Extracellular Matrix Proteins in MDCK Cells. Cancer microenvironment : official journal of the International Cancer Microenvironment Society 10 21505559
2025 Chronic stress induces depression through MDGA1-Neuroligin2 mediated suppression of inhibitory synapses in the lateral habenula. Theranostics 9 39897557
2024 Functional Neuroligin-2-MDGA1 interactions differentially regulate synaptic GABAARs and cytosolic gephyrin aggregation. Communications biology 9 39284869
2023 Contrastsing synaptic roles of MDGA1 and MDGA2. bioRxiv : the preprint server for biology 7 37720016
2023 Upregulation of Spinal MDGA1 in Rats After Nerve Injury Alters Interactions Between Neuroligin-2 and Postsynaptic Scaffolding Proteins and Increases GluR1 Subunit Surface Delivery in the Spinal Cord Dorsal Horn. Neurochemical research 4 37955815
2024 Impaired Hippocampal Long-Term Potentiation and Memory Deficits upon Haploinsufficiency of MDGA1 Can Be Rescued by Acute Administration of D-Cycloserine. International journal of molecular sciences 3 39273620
2025 Preliminary findings of DNA hypermethylation of MDGA1 in idiopathic restless legs syndrome. Sleep medicine 1 40058148
2026 Localization and Functional Characterization of MDGA1 in Mouse Hippocampus. The Journal of neuroscience : the official journal of the Society for Neuroscience 0 41530055
2026 Bazedoxifene reverses sexually dimorphic autistic-like abnormalities in biallelic MDGA1-mutant mice. EMBO molecular medicine 0 41862769
2025 MDGA1 Gene Variants and Risk for Restless Legs Syndrome. International journal of molecular sciences 0 40724952
2009 WITHDRAWN: Common polymorphisms in the MDGA1 gene are associated with bipolar disorder and schizophrenia in the Chinese Han population. Progress in neuro-psychopharmacology & biological psychiatry 0 20036297

Missed literature

Know a paper Affinage missed for MDGA1? Flag it for the maintainers and the community.

No submissions yet.