<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">slc6a17</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>SLC6A17</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Solute Carrier Family 6 Member 17 (Putative Neutral Amino Acid Transporter)</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>4q12</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>388939</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>608100</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000145936</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q9H0Y3</td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>614 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~67 kDa</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td>Intellectual Disability, Autism Spectrum Disorder, Epilepsy, Parkinson's Disease</td>
</tr>
<tr>
<td class="label">Substrate</td>
<td>Affinity</td>
</tr>
<tr>
<td class="label">Proline</td>
<td>High</td>
</tr>
<tr>
<td class="label">Glycine</td>
<td>High</td>
</tr>
<tr>
<td class="label">Alanine</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Serine</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Threonine</td>
<td>Low</td>
</tr>
<tr>
<td class="label">Glutamine</td>
<td>Low</td>
</tr>
<tr>
<td class="label">B
<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">slc6a17</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>SLC6A17</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Solute Carrier Family 6 Member 17 (Putative Neutral Amino Acid Transporter)</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>4q12</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>388939</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>608100</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000145936</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q9H0Y3</td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>614 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~67 kDa</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td>Intellectual Disability, Autism Spectrum Disorder, Epilepsy, Parkinson's Disease</td>
</tr>
<tr>
<td class="label">Substrate</td>
<td>Affinity</td>
</tr>
<tr>
<td class="label">Proline</td>
<td>High</td>
</tr>
<tr>
<td class="label">Glycine</td>
<td>High</td>
</tr>
<tr>
<td class="label">Alanine</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Serine</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Threonine</td>
<td>Low</td>
</tr>
<tr>
<td class="label">Glutamine</td>
<td>Low</td>
</tr>
<tr>
<td class="label">Brain Region</td>
<td>Expression Level</td>
</tr>
<tr>
<td class="label">Hippocampus</td>
<td>High</td>
</tr>
<tr>
<td class="label">Cortex</td>
<td>High</td>
</tr>
<tr>
<td class="label">Basal Ganglia</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Cerebellum</td>
<td>Low</td>
</tr>
<tr>
<td class="label">Thalamus</td>
<td>Low</td>
</tr>
<tr>
<td class="label">Brainstem</td>
<td>Low</td>
</tr>
</table>
The SLC6A17 gene (Solute Carrier Family 6 Member 17) encodes a putative neutral amino acid transporter that is predominantly expressed in the brain. This transporter is primarily localized to synaptic vesicles and presynaptic terminals, suggesting a role in synaptic transmission and neurotransmitter loading. The gene has attracted significant attention due to its association with neurodevelopmental disorders including intellectual disability, autism spectrum disorder, and seizures, making it an important target for understanding the molecular basis of neurological diseases [1].
Unlike most members of the SLC6 family, which transport classical neurotransmitters like GABA, dopamine, or serotonin, SLC6A17 transports neutral amino acids including proline, glycine, and alanine. This suggests a unique role in synaptic biology, possibly related to the loading of synaptic vesicles with neurotransmitter candidates or the regulation of amino acid homeostasis at synaptic terminals. The brain-specific expression pattern and presynaptic localization make SLC6A17 a distinctive member of the transporter family [2].
The SLC6A17 protein shares the characteristic 12-transmembrane domain architecture of the SLC6 family but exhibits unique features [3]:
N-terminal extracellular domain: Contains potential glycosylation sites that may affect trafficking and function.
Transmembrane domains: The 12 transmembrane helices form the central pore for substrate translocation. Unique residues in the substrate binding site may confer specificity for neutral amino acids.
Intracellular domains: The intracellular loops contain trafficking signals and potential phosphorylation sites.
C-terminal cytoplasmic domain: Contains motifs for protein interactions and synaptic vesicle targeting.
SLC6A17 transports neutral amino acids [4]:
SLC6A17 shows distinctive subcellular localization:
SLC6A17 exhibits a brain-specific expression pattern [5]:
The highest expression is in hippocampal CA1-CA3 pyramidal cells and cortical pyramidal neurons, regions critical for learning and memory.
SLC6A17 expression changes during development:
SLC6A17 may play several roles in synaptic transmission [6]:
Neurotransmitter loading: May contribute to the loading of synaptic vesicles with glycine or other neutral amino acid neurotransmitters.
Vesicular homeostasis: Helps maintain amino acid composition within synaptic vesicles.
Synaptic plasticity: May regulate synaptic strength through amino acid availability.
At presynaptic terminals, SLC6A17 contributes to [7]:
Terminal amino acid balance: Maintains intracellular amino acid pools.
Metabolic coupling: Links neuronal metabolism to synaptic function.
Signal termination: May help regulate extracellular amino acid levels.
In neurons, SLC6A17 supports:
Amino acid metabolism: Provides precursors for neurotransmitter synthesis.
Protein synthesis: Supplies amino acids for local protein synthesis.
Ion homeostasis: May influence neuronal excitability.
SLC6A17 is strongly associated with intellectual disability [8]:
Genetic variants: Loss-of-function mutations cause autosomal recessive intellectual disability.
Clinical features: Moderate to severe ID, speech delay, no dysmorphic features.
Mechanism: Altered presynaptic function affects neuronal circuit development.
SLC6A17 may contribute to ASD [9]:
Genetic association: Rare variants identified in ASD patients.
Network dysfunction: Altered synaptic function may affect neural connectivity.
Comorbidity: High rates of seizures with ASD.
SLC6A17 is relevant to epilepsy [10]:
Seizure susceptibility: Some variants predispose to seizures.
Mechanism: Altered synaptic function affects network excitability.
Therapeutic implications: Targeting SLC6A17 may have anti-seizure effects.
SLC6A17 may be relevant to PD [@nakamura2019]:
Expression changes: Altered expression in PD postmortem tissue.
Synaptic dysfunction: PD involves synaptic vulnerability.
Therapeutic targeting: Modulating SLC6A17 may offer neuroprotection.
Basal ganglia involvement: SLC6A17 is expressed in the basal ganglia, particularly in medium spiny neurons. Changes in GABAergic and glycinergic signaling contribute to motor dysfunction in PD.
Alpha-synuclein pathology: Preclinical studies suggest SLC6A17 expression may be affected by alpha-synuclein aggregation, potentially disrupting synaptic amino acid homeostasis.
Levodopa-induced dyskinesias: Altered glycine and proline transport may contribute to the development of dyskinesias in PD patients undergoing levodopa therapy.
SLC6A17 may contribute to schizophrenia [@pare2018]:
Genetic associations: Some genetic variants identified.
Synaptic dysfunction: Schizophrenia involves synaptic alterations.
Neurotransmitter changes: Amino acid neurotransmitter changes.
NMDA receptor modulation: SLC6A17 may influence glycine levels that modulate NMDA receptor function, relevant to the glutamatergic hypothesis of schizophrenia.
Cognitive deficits: Synaptic dysfunction involving SLC6A17 may contribute to cognitive impairments in schizophrenia.
Emerging evidence links SLC6A17 to AD:
Synaptic vulnerability: Early synaptic changes in AD affect amino acid transport proteins.
Memory consolidation: Hippocampal SLC6A17 may play roles in memory-related synaptic plasticity.
Network dysfunction: Altered transporter expression contributes to hippocampal network oscillations.
SLC6A17 has emerging relevance to ALS:
Motor neuron excitability: Altered amino acid transport affects motor neuron function.
Presynaptic dysfunction: Vesicular amino acid transporter changes in ALS.
Therapeutic implications: Targeting SLC6A17 may provide neuroprotection.
SLC6A17 expression is regulated by [13]:
Transcriptional regulation: Activity-dependent transcription factors.
Post-translational regulation: Phosphorylation, glycosylation.
Activity-dependent changes: Neuronal activity modulates expression.
SLC6A17 interacts with:
SLC6A17 trafficking:
No SLC6A17-targeted drugs are currently approved. Research strategies include:
Gene therapy: Viral vector delivery of functional SLC6A17.
Small molecule modulators: Developing transporter modulators.
Protein replacement: Enzyme replacement therapy approaches.
SLC6A17 knockout mice show:
Transgenic models are used to study disease mechanisms:
SLC6A17 interacts with:
SLC6A17 function is regulated by:
Activity-dependent phosphorylation: CaMKII-mediated phosphorylation affects trafficking.
Protein kinase C: PKC activation modulates transporter activity.
Calcium signaling: Calcium-dependent mechanisms influence function.
SLC6A17 trafficking:
SLC6A17 shows distinct evolutionary patterns:
Mammalian conservation: Highly conserved in mammals Brain-specific expression: Evolutionarily linked to complex nervous systems Synaptic specialization: Correlates with synaptic complexity
SLC6A17 mutations can be identified through:
The study of SLC6A17 has provided unique insights into brain-specific amino acid transport and synaptic function. Unlike other SLC6 family members that transport classical neurotransmitters, SLC6A17 transports neutral amino acids and localizes to synaptic vesicles, suggesting specialized functions.
Early research characterized the substrate specificity and tissue distribution of SLC6A17, establishing its brain-specific expression pattern and presynaptic localization. The identification of disease-causing mutations established its clinical importance.
Subsequent work established the roles of SLC6A17 in intellectual disability and other neurodevelopmental disorders. The presynaptic localization suggests functions in synaptic transmission that are critical for proper neuronal circuit formation and function.
More recent investigations have explored SLC6A17 as a therapeutic target. The development of gene therapy approaches for SLC6A17-related disorders offers hope for treatment.