## GRIN2A Protein is a protein. This page describes its structure, normal nervous system function, role in neurodegenerative disease, and potential as a therapeutic target.
GRIN2A encodes the NMDAR2A (NR2A) subunit, a regulatory subunit of NMDA receptors. NR2A subunits determine pharmacological and biophysical properties of the receptor complex.
Key structural features:
- Extracellular agonist-binding domain (ABD): Binds glutamate with high affinity
- Transmembrane domain (M1-M4): Forms the ion channel pore
- C-terminal domain (CTD): Long intracellular tail (~400 aa) for protein interactions
- PDZ-binding motif: Interacts with PSD-95 and other scaffolding proteins
NR2A-containing NMDARs have distinct properties:
- Synaptic exclusivity: Primarily localized at synaptic sites
- LTP induction: Required for efficient long-term potentiation
- Memory consolidation: Critical for memory formation and stabilization
- Developmental switch: NR2A expression increases during development
- Activity-dependent: Synaptic activity upregulates NR2A
- Trafficking: Forward trafficking to synapses requires interaction with PSD-95
- Ca2+ signaling: Triggers Ca2-dependent signaling cascades
- Gene regulation: Activates transcription factors (CREB, NF-κB)
- Synaptic plasticity: Regulates both LTP and LTD
GRIN2A alterations contribute to neurodegenerative processes:
- Synaptic loss: Reduced NR2A/NR2B ratio in AD hippocampus
- Excitotoxicity: Altered subunit composition increases vulnerability
- Cognitive decline: NR2A dysfunction correlates with memory deficits
- Tau pathology: Tau affects NMDAR trafficking and function
- Striatal dysfunction: Altered NR2A expression in striatum
- LTP deficits: Impaired corticostriatal plasticity
- Dyskinesias: NMDAR subunit changes contribute to L-DOPA-induced dyskinesias
- Epileptic encephalopathy: GRIN2A mutations cause epilepsy-aphasia spectrum
- Channelopathy: Gain-of-function and loss-of-function mutations
- Therapeutic implications: Antagonists vs. agonists depend on mutation type
- Ischemic vulnerability: NR2A-containing receptors are more vulnerable
- Excitotoxic death: Contributes to post-ischemic neuronal damage
GRIN2A is a target for modulation:
- Ifenprodil: NR2B-selective (not NR2A)
- Investigational NR2A modulators: In development
- Positive allosteric modulators: Enhance NR2A function for cognitive enhancement
- Subunit-selective antagonists: May provide neuroprotection with fewer side effects
- Gene therapy: Future potential for specific subunit targeting
GRIN2A encodes the GluN2A subunit of NMDA receptors:
- High calcium permeability
- Mg²⁺ voltage-dependent block
- Na⁺ and K⁺ permeability
- Slow deactivation kinetics
NMDA receptors containing GRIN2A mediate:
GRIN2A alterations in AD:
- Reduced channel function
- Synaptic plasticity deficits
- Excitotoxicity vulnerability
- Interactions with amyloid-β
- Altered NMDA plasticity in PD
- Levodopa-induced dyskinesias
- Dopamine-NMDA interactions
- Motor cortex hyperexcitability
- Motor neuron excitability
- Glutamate excitotoxicity
- Altered channel function
- Treatment implications
- Ischemic damage mechanisms
- Excitotoxic cell death
- Therapeutic targets
- GRIN2A mutations cause epilepsy
- Channel hyperactivity
- Treatment resistance
¶ Structure and Function
¶ Protein Domains
| Domain |
Function |
| Extracellular NTD |
Agonist binding |
| Ligand-binding domain |
Glutamate, glycine |
| Transmembrane domains |
Ion pore |
| C-terminal domain |
Synaptic localization |
- Phosphorylation (multiple sites)
- Glycosylation
- Palmitoylation
- Nitrosylation
| Compound |
Mechanism |
Status |
| Memantine |
Channel blocker |
Approved for AD |
| Esketamine |
NMDA antagonist |
Approved for depression |
| Dapecant |
NR2A-selective |
Preclinical |
- AAV-GRIN2A delivery
- siRNA approaches
- CRISPR editing
Grin2a-/- mice:
- Reduced LTP
- Learning deficits
- Increased mortality
- Human GRIN2A knock-in
- Mutant GRIN2A expression
- Disease-associated variants
| Mutation |
Phenotype |
Mechanism |
| Missense |
Epilepsy |
Gain-of-function |
| Truncating |
DD/ID |
Loss-of-function |
| Deletions |
Various |
haploinsufficiency |
- Common variants in psychiatric disorders
- Population frequencies
- Functional effects