GRIK5 - Glutamate Receptor Kainate Type Subunit 5
Introduction
<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">GRIK5 - Glutamate Receptor Kainate Type Subunit 5</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td>GRIK5</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Glutamate Ionotropic Receptor Kainate Type Subunit 5</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>19q13.33</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>2896</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000146013</td>
</tr>
<tr>
<td class="label">OMIM ID</td>
<td>604765</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q9NSU7</td>
</tr>
<tr>
<td class="label">Therapeutic Strategy</td>
<td>Mechanism</td>
</tr>
<tr>
<td class="label">Kainate receptor antagonists</td>
<td>Block excitotoxic signaling</td>
</tr>
<tr>
<td class="label">Positive allosteric modulators</td>
<td>Enhance normal synaptic function</td>
</tr>
<tr>
<td class="label">Gene therapy</td>
<td>Modulate receptor expression</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
Grik5 Glutamate Receptor Kainate Type Subunit 5 is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Overview
GRIK5 (Glutamate Ionotropic Receptor Kainate Type Subunit 5) encodes the glutamate receptor 5 (GluR5) subunit, also known as kainate receptor subunit 5 (KA5). GRIK5 is a member of the ionotropic glutamate receptor family and forms functional kainate receptors when assembled with other GRIK subunits (GRIK1, GRIK2, GRIK3, or GRIK4). These receptors play crucial roles in excitatory synaptic transmission, neuronal development, and circuit formation throughout the central nervous system. [@contractor2001]
Protein Structure and Function
GRIK5 encodes a kainate receptor subunit that contains several key structural features:
- Ligand-binding domain (LBD): The extracellular domain contains the glutamate binding site, which undergoes conformational changes upon agonist binding
- Transmembrane domain: Four hydrophobic segments that form the ion channel pore
- Intracellular C-terminal domain: Contains PDZ-binding motifs and phosphorylation sites for receptor trafficking and regulation
Kainate receptors including those containing GRIK5 subunits exhibit unique pharmacological properties compared to AMPA and [NMDA](/entities/nmda-receptor) receptors, with intermediate conductance and voltage-dependent kinetics.
Normal Function
- Excitatory synaptic transmission: GRIK5-containing kainate receptors contribute to basal excitatory neurotransmission in hippocampal and cortical circuits
- Neuronal development: During development, kainate receptors regulate neurite outgrowth, synapse formation, and circuit maturation
- Synaptic plasticity: These receptors modulate [long-term potentiation](/mechanisms/long-term-potentiation) (LTP) and long-term depression (LTD) in specific brain regions
- Neuroendocrine regulation: GRIK5 is expressed in hypothalamic nuclei and regulates hormone release
Brain Region Distribution
GRIK5 exhibits region-specific expression patterns:
- [Hippocampus](/brain-regions/hippocampus): High expression in CA3 region and dentate gyrus mossy fiber pathways
- Cerebral [cortex](/brain-regions/cortex): Moderate expression in layers II-III and V
- Cerebellum: Expression in granule cells and molecular layer
- Thalamus: Present in specific nuclei including the lateral geniculate nucleus
- Amygdala: Expression in basal and lateral nuclei
Disease Associations
Alzheimer's Disease
Kainate receptors containing GRIK5 subunits are implicated in Alzheimer's disease pathogenesis through several mechanisms:
- Glutamate excitotoxicity: [Aβ](/proteins/amyloid-beta) oligomers can potentiate kainate receptor activity, leading to excessive calcium influx and neuronal dysfunction
- Synaptic loss: Dysregulation of GRIK5-containing receptors contributes to synaptic spine degeneration
- Cognitive impairment: Altered kainate receptor signaling in hippocampal circuits may contribute to memory deficits
Parkinson's Disease
- Basal ganglia circuitry: GRIK5 in striatal and subthalamic [neurons](/entities/neurons) may influence motor control circuits affected in PD
- Excitotoxicity: Dopaminergic degeneration may be exacerbated by dysregulated glutamate receptor activity
- L-DOPA-induced dyskinesias: Kainate receptor antagonists have shown promise in reducing dyskinesia severity
Amyotrophic Lateral Sclerosis (ALS)
- Motor neuron vulnerability: Altered kainate receptor expression may contribute to excitotoxic motor neuron death
- Glutamate metabolism: Impaired glutamate transporter function in ALS may enhance kainate receptor-mediated toxicity
Epilepsy
- Seizure susceptibility: GRIK5 genetic variants have been associated with epilepsy susceptibility
- Temporal lobe epilepsy: Altered expression of kainate receptor subunits in hippocampal circuits
Psychiatric Disorders
- Depression and anxiety: Kainate receptors modulate serotonergic and dopaminergic circuits involved in mood regulation
- Schizophrenia: Altered glutamatergic signaling through kainate receptors may contribute to cognitive deficits
Therapeutic Implications
GRIK5-containing kainate receptors represent potential therapeutic targets:
Drug Development Challenges
- Subunit selectivity: Developing compounds that target GRIK5-containing receptors without affecting other kainate receptor subtypes
- [Blood-brain barrier](/entities/blood-brain-barrier) penetration: Ensuring CNS delivery of therapeutic compounds
- Physiological function preservation: Avoiding complete receptor blockade that could impair normal neurotransmission
Key Publications
Chittajallu R, et al. (1999). 'Regulation of kainate receptors.' Advances in Experimental Medicine and Biology. PMID: 10352611(https://pubmed.ncbi.nlm.nih.gov/10352611/)
2.Contractor A, et al. (2001). 'Kainate receptors are involved in synaptic plasticity.'
Nature.
PMID: 11452077(https://pubmed.ncbi.nlm.nih.gov/11452077/)
3.Lerma J, et al. (2001). 'Molecular physiology of kainate receptors.'
Nature Reviews Neuroscience.
PMID: 11750243(https://pubmed.ncbi.nlm.nih.gov/11750243/)
4.Pinheiro P, et al. (2007). 'Kainate receptor subunits.'
European Journal of Neuroscience.
PMID: 17284184(https://pubmed.ncbi.nlm.nih.gov/17284184/)
5.Crepel V, et al. (2003). 'Kainate and epilepsy.'
Cellular and Molecular Life Sciences.
PMID: 14523549(https://pubmed.ncbi.nlm.nih.gov/14523549/)
See Also
- [Glutamate Receptors](/glutamate-receptors-in-neuronal-function)
- [Kainate Receptors](/entities/kainate-receptors)
- [GRIK1](/proteins/grik1)
- [GRIK2](/proteins/grik2)
- [GRIK3](/proteins/grik3)
- [GRIK4](/proteins/grik4)
- [Excitotoxicity](/mechanisms/excitotoxicity)
- [AMPA Receptors](/proteins/ampa-receptor)
- [NMDA Receptors](/entities/nmda-receptor)
External Links
- [NCBI Gene: GRIK5](https://www.ncbi.nlm.nih.gov/gene/2896)
- [UniProt: Q9NSU7](https://www.uniprot.org/uniprot/Q9NSU7)
- [Ensembl: ENSG00000146013](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000146013)
- [Human Protein Atlas: GRIK5](https://www.proteinatlas.org/ENSG00000146013-GRIK5)
Background
The study of Grik5 Glutamate Receptor Kainate Type Subunit 5 has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
References
[Chittajallu R, et al, (1999) (1999)](https://pubmed.ncbi.nlm.nih.gov/10352611/)
[Contractor A, et al, (2001) (2001)](https://pubmed.ncbi.nlm.nih.gov/11452077/)
[Lerma J, et al, (2001) (2001)](https://pubmed.ncbi.nlm.nih.gov/11750243/)
[Pinheiro P, et al, (2007) (2007)](https://pubmed.ncbi.nlm.nih.gov/17284184/)
[Crepel V, et al, (2003) (2003)](https://pubmed.ncbi.nlm.nih.gov/14523549/)
[Bureau I, et al, (1999) (1999)](https://pubmed.ncbi.nlm.nih.gov/10530809/)
[Wisden W, et al, (1993) (1993)](https://pubmed.ncbi.nlm.nih.gov/7695198/)
[Gallagher MJ, et al, (2004) (2004)](https://pubmed.ncbi.nlm.nih.gov/15111012/)