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SLC18A3
solute carrier family 18 member A3
SLC18A3 is located on the long (q) arm of chromosome 10, at band 10q11.23. Arm ratio per GRCh38 - banding schematic.
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Overview
SLC18A3 (solute carrier family 18 member A3) encodes the vesicular acetylcholine transporter, commonly known as VAChT. This transporter protein is essential for the proper functioning of cholinergic neurons, which use acetylcholine as their primary neurotransmitter. VAChT is responsible for loading acetylcholine molecules into synaptic vesicles within nerve terminals, a crucial step that enables controlled release of this neurotransmitter during nerve signalling.
Cholinergic neurotransmission mediated by acetylcholine influences numerous physiological processes, including muscle contraction, autonomic nervous system function, and various cognitive processes in the brain. The SLC18A3 gene is located on chromosome 10 and belongs to a broader family of vesicular transporters that manage the storage and release of different neurotransmitters across the nervous system.
What the gene does
The protein encoded by SLC18A3 operates as a membrane-bound transporter embedded in the walls of synaptic vesicles within cholinergic nerve terminals. Its primary function is to concentrate acetylcholine inside these vesicles, creating a reservoir of neurotransmitter ready for rapid release when the neuron fires. This transport process is driven by an electrochemical gradient established by a proton pump, with VAChT exchanging protons for acetylcholine molecules.
The efficiency of this transport mechanism directly determines how much acetylcholine can be packaged and subsequently released during synaptic transmission. When a nerve impulse arrives at the terminal, the acetylcholine-filled vesicles fuse with the cell membrane, releasing their contents into the synaptic cleft. The released acetylcholine then binds to receptors on target cells, propagating the nerve signal. This process is fundamental to neuromuscular junctions, where motor neurons signal muscle fibres to contract, and to parasympathetic nervous system functions including heart rate regulation and digestive processes.
Without functional VAChT, cholinergic neurons cannot effectively store acetylcholine, severely compromising their ability to transmit signals. The transporter's activity is therefore essential for maintaining normal cholinergic neurotransmission throughout both the central and peripheral nervous systems.
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Chromosome location
The SLC18A3 gene is located on the long arm of chromosome 10 at position 11.23, designated as 10q11.23. This chromosomal region contains a cluster of genes involved in various transport and signalling functions. The genomic organisation of SLC18A3 places it within a broader regulatory context that influences its expression patterns across different neuronal populations.
Protein structure
Domain architecture has not been experimentally characterised in detail for this protein. However, as a member of the solute carrier family, the VAChT protein is predicted to contain multiple transmembrane segments that span the vesicle membrane, creating a channel-like structure through which acetylcholine molecules pass. These membrane-spanning regions are thought to form the core transport machinery, whilst loops between the segments may contribute to substrate recognition and binding specificity.
Key variants
Genetic variants in SLC18A3 can affect the transporter's expression levels or functional efficiency, potentially influencing cholinergic neurotransmission capacity. Both coding variants that alter the protein sequence and regulatory variants affecting gene expression have been identified. The clinical significance of many SLC18A3 variants remains under investigation, with research examining how specific changes might contribute to neurological or neuromuscular phenotypes.
No pathogenic or likely-pathogenic ClinVar variants recorded yet for this gene.
Associated conditions
Research into SLC18A3 variants has explored potential associations with conditions affecting cholinergic neurotransmission, though definitive disease links continue to be characterised. Given the protein's fundamental role in acetylcholine handling, variants could theoretically influence susceptibility to disorders involving cholinergic dysfunction. However, establishing clear genotype-phenotype correlations requires additional investigation across larger patient cohorts.
No disease links recorded for this gene in our reference set.
UK clinical status
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
What does the SLC18A3 gene do?
SLC18A3 encodes the vesicular acetylcholine transporter (VAChT), which loads acetylcholine into synaptic vesicles within cholinergic nerve terminals. This process is essential for enabling controlled release of acetylcholine during nerve signalling.
Where is the SLC18A3 gene located?
The SLC18A3 gene is located on chromosome 10 at position 10q11.23, on the long arm of the chromosome.
How does VAChT support nerve function?
VAChT concentrates acetylcholine inside synaptic vesicles by transporting it across the vesicle membrane. When a nerve impulse arrives, these acetylcholine-filled vesicles release their contents to transmit signals to the next cell, supporting functions including muscle contraction and autonomic nervous system activity.