Affinage

GRID2

Glutamate receptor ionotropic, delta-2 · UniProt O43424

Length
1007 aa
Mass
113.4 kDa
Annotated
2026-06-10
29 papers in source corpus 8 papers cited in narrative 8 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 5/5 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

GRID2 encodes the GluD2 ionotropic glutamate receptor delta subunit that organizes excitatory synapse formation in the cerebellum, where it localizes to Purkinje cell dendritic spines in both mouse and human (PMID:7736576, PMID:24078737). Loss of GRID2 impairs the formation of both parallel fiber- and climbing fiber-Purkinje cell synapses, abolishes long-term depression of parallel fiber synaptic transmission, and produces motor incoordination (PMID:7736576), and its deletion additionally perturbs NMDA and AMPA receptor signaling in cerebellar granule cells (PMID:25513882). The Lurcher mutation (A654T) in the M3 transmembrane domain converts the receptor into a constitutively open channel that drives persistent membrane depolarization and Purkinje cell death (PMID:10414327); this death proceeds at least in part through a depolarization-independent autophagy route engaging the GRID2-nPIST-Beclin1 signaling pathway (PMID:12628171). Human gain-of-function missense mutations at Ala654 and adjacent M3 residues (Leu656, T649A) recapitulate this constitutive activity and cause semidominant cerebellar ataxia, and the constitutive current of the GluD2-T649A variant is potently blocked by pentamidine (PMID:25841024, PMID:37944084). GRID2 is also expressed in human and murine retina and retinal pigment epithelium, indicating function beyond Purkinje cells (PMID:25122145).

Mechanistic history

Synthesis pass · year-by-year structured walk · 7 steps
  1. 1995 High

    Established that GRID2 is required for cerebellar synapse formation and synaptic plasticity, defining its core role before any channel or signaling mechanism was known.

    Evidence Knockout mouse with electrophysiology and histology

    PMID:7736576

    Open questions at the time
    • Did not resolve whether GRID2 acts as a functional ion channel or a structural synaptic organizer
    • Molecular partners mediating synapse formation not identified
  2. 1999 High

    Showed the Lurcher A654T mutation converts GRID2 into a constitutively open channel, linking a single M3 residue to membrane depolarization and Purkinje cell death.

    Evidence Electrophysiology in Xenopus oocytes and patch-clamp of Purkinje cells with gain-of-function mutant

    PMID:10414327

    Open questions at the time
    • Did not establish whether depolarization alone is sufficient to cause cell death
    • Endogenous ligand or gating mechanism of wild-type receptor not defined
  3. 2003 High

    Dissociated Lurcher-induced cell death from depolarization by identifying a GRID2-nPIST-Beclin1 autophagy pathway, revealing a non-channel signaling route to neurodegeneration.

    Evidence Genetic epistasis with Lurcher/hotfoot heteroallelic mutants and autophagy marker immunofluorescence

    PMID:12628171

    Open questions at the time
    • Biochemical mechanism by which GRID2 engages nPIST and Beclin1 not detailed
    • Relative contribution of autophagy versus depolarization-driven death not quantified
  4. 2013 Medium

    Confirmed conserved dendritic spine localization of GRID2 in human as well as mouse Purkinje cells, supporting translational relevance of the mouse synaptic model.

    Evidence Immunohistochemistry on mouse and human cerebellar specimens

    PMID:24078737

    Open questions at the time
    • No functional manipulation in this study
    • Did not address sub-spine distribution or partner colocalization
  5. 2014 Medium

    Extended GRID2 function beyond the cerebellum by demonstrating expression in retina and retinal pigment epithelium, and showed Grid2 deletion alters granule-cell NMDA and AMPA receptor currents.

    Evidence Immunohistochemistry and RT-qPCR on retinal tissue; patch-clamp on KO granule cells with optokinetic assay

    PMID:25122145 PMID:25513882

    Open questions at the time
    • Functional role of GRID2 in retina not tested
    • Magnitude and mechanism of the granule-cell receptor effect modest and from single studies
  6. 2014 Medium

    Translated the Lurcher mechanism to human disease by identifying gain-of-function M3 mutations at Ala654 and Leu656 causing semidominant cerebellar ataxia.

    Evidence Whole-exome sequencing and genetic analysis with mechanism inferred from prior Lurcher work

    PMID:25841024

    Open questions at the time
    • No new in vitro functional assay of the human variants in this study
    • Loss-of-function human alleles not characterized here
  7. 2024 High

    Demonstrated that multiple M3 variants produce constitutive activity and that pentamidine pharmacologically blocks the constitutive current, providing a candidate therapeutic strategy and structure-function map of M3 intolerance.

    Evidence Patch-clamp electrophysiology, site-directed mutagenesis, complex-formation biochemistry, and pharmacological inhibition

    PMID:37944084

    Open questions at the time
    • In vivo efficacy of pentamidine not tested
    • Endogenous gating ligand of GRID2 remains undefined

Open questions

Synthesis pass · forward-looking unresolved questions
  • The physiological gating ligand and the molecular basis by which GRID2 organizes presynaptic-postsynaptic contacts remain unresolved.
  • No endogenous agonist defined for wild-type GRID2
  • Structural mechanism of trans-synaptic synapse organization not established in the corpus

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Localization
GO:0005886 plasma membrane 1
Pathway
R-HSA-112316 Neuronal System 1 R-HSA-9612973 Autophagy 1
Partners
BECLIN1NPIST

Evidence

Reading pass · 8 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1995 GluR delta 2 (GRID2) is required for formation of parallel fiber-Purkinje cell synapses and climbing fiber-Purkinje cell synapses in the cerebellum, and for long-term depression of parallel fiber-Purkinje cell synaptic transmission; loss-of-function knockout mice show impaired motor coordination. Gene targeting (knockout mouse), electrophysiology, histology Cell High 7736576
1999 The Lurcher mutation (A654T) in transmembrane domain III of GRID2 converts the receptor into a constitutively active ion channel, causing persistent membrane depolarization and subsequent apoptotic Purkinje cell death; confirmed by expression in Xenopus oocytes showing large constitutive inward current. Electrophysiology in Xenopus oocytes, patch-clamp of Purkinje cells, gain-of-function mutation analysis Annals of the New York Academy of Sciences High 10414327
2003 Lurcher GRID2-induced Purkinje cell death can be dissociated from constitutive depolarization: in Lurcher/hotfoot heteroallelic mutants (one Lurcher allele, no wild-type GRID2), early massive Purkinje cell death occurs via autophagy activation through the GRID2–nPIST–Beclin1 signaling pathway, independently of depolarization. Genetic epistasis using Lurcher/hotfoot heteroallelic mutants, histology, immunofluorescence for autophagy markers Neuron High 12628171
2013 GRID2 localizes to Purkinje cell dendritic spines in both developing mouse and human cerebella, consistent with a conserved role in parallel fiber-Purkinje cell synapse organization. Immunohistochemistry on mouse and human brain specimens Neurology Medium 24078737
2014 GRID2 missense mutations at Ala654 (equivalent to the Lurcher site) and nearby residue Leu656 in the M3 transmembrane domain create constitutively active receptors, producing gain-of-function cerebellar ataxia with semidominant transmission in humans, mirroring the Lurcher mouse mechanism. Whole-exome sequencing, genetic analysis, clinical electrophysiology inference; functional characterization referenced from prior Lurcher studies Neurology Medium 25841024
2014 GRID2 is expressed in human adult retina and retinal pigment epithelium, as well as in murine retina at multiple developmental stages, indicating a functional role for GRID2 beyond cerebellar Purkinje cells. Immunohistochemistry, RT-qPCR on human and murine retinal tissue Genetics in medicine Medium 25122145
2014 Grid2 deletion in mice alters NMDA receptor-dependent currents in cerebellar granule cells (patch-clamp showed relatively small but detectable change), and also affects AMPA receptor function, suggesting GRID2 is important for correct NMDA and AMPA receptor signaling in granule cells. Patch-clamp electrophysiology on cultured granule cells from Grid2-deleted mice, optokinetic response behavioral assay Genes Medium 25513882
2024 Multiple rare GRID2 variants in the M3 transmembrane domain create constitutively active receptors; pentamidine potently inhibits constitutive currents of the GluD2-T649A variant (IC50 ~50 nM). A GRID1 variant at the predicted Cbln2/Cbln4 interaction site disrupts complex formation between GluD1 and Cbln2; GRID2 M3 domain shows different intolerance to variation compared to GRID1 M3. Electrophysiology (patch-clamp), biochemical assays (complex formation), site-directed mutagenesis, pharmacological inhibition Human molecular genetics High 37944084

Source papers

Stage 0 corpus · 29 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1995 Impairment of motor coordination, Purkinje cell synapse formation, and cerebellar long-term depression in GluR delta 2 mutant mice. Cell 483 7736576
2013 Deletions in GRID2 lead to a recessive syndrome of cerebellar ataxia and tonic upgaze in humans. Neurology 81 24078737
2003 Lurcher GRID2-induced death and depolarization can be dissociated in cerebellar Purkinje cells. Neuron 66 12628171
2015 GRID2 mutations span from congenital to mild adult-onset cerebellar ataxia. Neurology 64 25841024
2013 A homozygous deletion in GRID2 causes a human phenotype with cerebellar ataxia and atrophy. Journal of child neurology 62 23611888
2014 Early-onset autosomal recessive cerebellar ataxia associated with retinal dystrophy: new human hotfoot phenotype caused by homozygous GRID2 deletion. Genetics in medicine : official journal of the American College of Medical Genetics 35 25122145
2013 De novo partial deletion in GRID2 presenting with complicated spastic paraplegia. Muscle & nerve 30 24122788
2017 Homozygous GRID2 missense mutation predicts a shift in the D-serine binding domain of GluD2 in a case with generalized brain atrophy and unusual clinical features. BMC medical genetics 24 29207948
2008 Discrimination learning in Rora(sg) and Grid2(ho) mutant mice. Neurobiology of learning and memory 20 18583162
1998 The human glutamate receptor delta 2 gene (GRID2) maps to chromosome 4q22. Genomics 20 9465309
2003 Motor coordination in mice with hotfoot, Lurcher, and double mutations of the Grid2 gene encoding the delta-2 excitatory amino acid receptor. Physiology & behavior 19 14637233
2014 The effect of genetic background on behavioral manifestation of Grid2(Lc) mutation. Behavioural brain research 16 24937052
2016 Potential of GRID2 receptor gene for preventing TNF-induced neurodegeneration in autism. Neuroscience letters 14 27019035
2024 Clinical features, functional consequences, and rescue pharmacology of missense GRID1 and GRID2 human variants. Human molecular genetics 13 37944084
1999 GluR delta 2 and the development and death of cerebellar Purkinje neurons in lurcher mice. Annals of the New York Academy of Sciences 13 10414327
2020 Autosomal recessive spinocerebellar ataxia 18 caused by homozygous exon 14 duplication in GRID2 and review of the literature. Acta neurologica Belgica 12 32170608
2017 A Rare Syndrome of GRID2 Deletion in 2 Siblings. Child neurology open 12 28856174
2019 Further delineation of the phenotype caused by a novel large homozygous deletion of GRID2 gene in an adult patient. Clinical case reports 11 31183084
2014 GRID2 a novel gene possibly associated with mevalonate kinase deficiency. Rheumatology international 11 25146332
2005 Two reciprocal translocations provide new clues to the high mutability of the Grid2 locus. Mammalian genome : official journal of the International Mammalian Genome Society 10 15674731
2014 Altered Actions of Memantine and NMDA-Induced Currents in a New Grid2-Deleted Mouse Line. Genes 9 25513882
2018 Evidence for generative homology of cerebellum and cerebellum-like structures in an elasmobranch fish based on Pax6, Cbln1 and Grid2 expression. The Journal of comparative neurology 7 29888788
2022 A heterozygous GRID2 mutation in autosomal dominant cerebellar ataxia. Human genome variation 5 35882834
2022 GRID2 aberration leads to disturbance in neuroactive ligand-receptor interactions via changes to the species richness and composition of gut microbes. Biochemical and biophysical research communications 5 36162328
2020 A case of severe autosomal recessive spinocerebellar ataxia type 18 with a novel nonsense variant in GRID2. European journal of medical genetics 5 32622959
2020 GRID2 Mutation-Related Spinocerebellar Ataxia Type 18: A New Report and Literature Review. Journal of pediatric genetics 4 35769960
2024 De Novo GRID2 Variant as a Cause of Ataxia with Oculomotor Apraxia and Alpha-Fetoprotein Elevation. Cerebellum (London, England) 3 39312122
2025 Integrated ATAC-seq and RNA-seq analysis identifies Grid2 and Reln as potential regulatory genes in migraine pathophysiology. The journal of headache and pain 0 41327020
2025 Peripheral GRID2 DNA methylation as a diagnostic biomarker for adolescent depression: Linking self-compassion to glutamatergic epigenetic changes. Journal of affective disorders 0 41371357

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