PSD93 (Postsynaptic Density Protein of 93 kDa), encoded by the DLG3 gene, is a member of the membrane-associated guanylate kinase (MAGUK) family of scaffolding proteins. It plays a critical role in the organization of postsynaptic density complexes at excitatory synapses and has been implicated in synaptic plasticity, learning, and memory.
| Property |
Value |
| Gene Symbol |
DLG3 |
| Official Name |
Discs Large Homolog 3 |
| Chromosomal Location |
Xq13.1 |
| NCBI Gene ID |
1749 |
| Ensembl ID |
ENSG00000165646 |
| UniProt ID |
Q92796 |
¶ Protein Structure and Function
¶ Domain Architecture
PSD93 contains multiple protein-protein interaction domains:
- N-terminal region: Palmitoylation site for membrane targeting
- PDZ domains (3x): PDZ1-3 mediate interactions with NMDA receptor subunits (NR2A/B), AMPA receptor subunits, and other synaptic proteins
- SH3 domain: Binds to proline-rich motifs
- Guanylate kinase (GK) domain: Catalytic domain with binding sites for GKAP/SAP90
PSD93 is a core component of the postsynaptic density (PSD) scaffold, forming a complex network with:
- NMDA receptors (via PDZ domains)
- AMPA receptors (via PDZ interactions with GRIP/ABP)
- Kainate receptors
- Shank proteins (connecting to actin cytoskeleton)
- CRASH/Cortactin (actin remodeling)
In AD, PSD93 alterations contribute to synaptic dysfunction through multiple mechanisms:
- NMDA receptor dysregulation: Altered PSD93 expression affects NMDAR localization and signaling
- AMPA receptor trafficking: Impaired AMPAR endocytosis and recycling
- Synaptic plasticity deficits: Disrupted LTP and LTD mechanisms
- Tau pathology: PSD93 interacts with tau and may influence tau-mediated synaptic damage
PSD93 has been implicated in PD through:
- Dopaminergic synapse function: Role in maintaining dopaminergic synaptic architecture
- Excitotoxicity: Interaction with NMDA receptors may contribute to excitotoxic cell death
- Mitochondrial dysfunction: Possible connections to mitochondrial quality control pathways
In ALS, PSD93 may play a role in:
- Motor neuron synaptic stability: Disruption of neuromuscular junction integrity
- Excitotoxicity: Altered glutamate receptor dynamics
- Axonal transport: Connections to cytoskeletal regulatory proteins
- Cerebral cortex: High expression in layers II-III and V
- Hippocampus: Strong expression in CA1 and dentate gyrus
- Striatum: Moderate expression in medium spiny neurons
- Cerebellum: Purkinje cell expression
- Brainstem: Moderate expression
- Neurons: Primary expression in excitatory (glutamatergic) neurons
- Astrocytes: Low expression
- Microglia: Minimal expression
- Oligodendrocytes: Not expressed
- PSD93-NMDAR interaction inhibitors: Potential neuroprotective agents
- PSD93 stability modulators: Enhance synaptic resilience
- PDZ domain modulators: Target protein-protein interactions
- CSF PSD93 levels: Possible biomarker for synaptic loss
- Postmortem brain tissue: Diagnostic aid for synaptic pathology
- X-linked mental retardation: DLG3 mutations associated with non-syndromic intellectual disability
- Epilepsy: Altered PSD93 expression in epileptic tissue
- Schizophrenia: Reduced PSD93 in prefrontal cortex
- Neurodevelopmental disorders: Synaptic scaffolding abnormalities
- PSD95 (DLG4) — Closely related MAGUK family member
- PSD93 (DLG2) — Another PSD93 homolog
- Shank3 — Postsynaptic scaffold interactor
- GRIP1 — AMPA receptor interacting protein
- NR2A — NMDA receptor subunit
- NR2B — NMDA receptor subunit