SLC6A4: Serotonin Transporter Gene - Function, Variants, and Clinical Significance
Comprehensive biomedical overview of SLC6A4 (5-HTT), including genomic context, expression, disease associations, and functional classification.
Gene Information Card
| Symbol | SLC6A4 |
|---|---|
| Full Name | Solute carrier family 6 member 4 |
| Gene Type | protein-coding |
| Chromosomal Location | 17q11.2 |
| NCBI Gene ID | 6532 ncbi.nlm.nih.gov/gene/6532 |
| Ensembl ID | ENSG00000108576 |
| UniProt ID | P31645 |
| OMIM ID | 182138 |
| HGNC ID | 11050 |
| Aliases | 5-HTT, SERT, HTT, OCD1, SERT1, 5HTT |
Description
The SLC6A4 gene encodes the serotonin transporter (SERT), a transmembrane protein responsible for the reuptake of serotonin (5-hydroxytryptamine, 5-HT) from the synaptic cleft back into presynaptic neurons. This transporter is a key regulator of serotonergic signaling and is the primary target of selective serotonin reuptake inhibitors (SSRIs) used in the treatment of depression and anxiety disorders. SLC6A4 is expressed predominantly in the brain, platelets, and gastrointestinal tract. Genetic variations, particularly the 5-HTTLPR polymorphism in the promoter region, influence transcriptional activity and have been associated with susceptibility to psychiatric disorders and antidepressant response.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Major Depressive Disorder | Reduced serotonin transporter expression due to the short (S) allele of 5-HTTLPR leads to altered serotonin reuptake and impaired stress response, increasing vulnerability to depression. | Multiple meta-analyses (e.g., Karg et al., 2011) show association between S allele and depression under stress; ClinVar lists SLC6A4 variants with risk for depression. |
| Obsessive-Compulsive Disorder (OCD) | Gain-of-function variants (e.g., 5-HTTLPR L allele) may increase serotonin reuptake, reducing synaptic serotonin and contributing to OCD symptoms. | Genetic association studies (e.g., Bengel et al., 1999) and ClinVar entries link SLC6A4 variants to OCD. |
| Autism Spectrum Disorder (ASD) | Altered serotonin transporter expression affects neurodevelopment and serotonin signaling, implicated in ASD pathophysiology. | Rare variants and 5-HTTLPR associations reported in ASD cohorts (e.g., Sutcliffe et al., 2005); ClinVar lists SLC6A4 as a candidate gene. |
| Alcohol Dependence | The S allele of 5-HTTLPR is associated with reduced transporter function, leading to altered serotonin turnover and increased impulsivity, contributing to alcohol dependence risk. | Meta-analyses (e.g., Feinn et al., 2005) support association; OMIM notes SLC6A4 involvement in addiction. |
| Irritable Bowel Syndrome (IBS) | SLC6A4 expression in gut regulates serotonin availability; altered transporter function affects gastrointestinal motility and sensitivity. | Expression studies and genetic associations (e.g., Yeo et al., 2004) link SLC6A4 variants to IBS. |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Brain (cerebral cortex) | ~10 | Medium |
| Brain (basal ganglia) | ~8 | Medium |
| Platelets | High (protein level) | High |
| Gastrointestinal tract (small intestine) | ~5 | Low |
| Lung | ~3 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| SH-SY5Y (neuroblastoma) | ~15 | Neuronal-like expression |
| Caco-2 (colorectal adenocarcinoma) | ~8 | Intestinal expression |
| HEK293 (embryonic kidney) | ~2 | Low endogenous expression |
| HepG2 (hepatocellular carcinoma) | ~1 | Very low |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| 5-HTTLPR (S/L) | Promoter polymorphism | S allele frequency ~40-50% in Caucasians | S allele reduces transcriptional efficiency, leading to lower SERT expression and altered serotonin reuptake. |
| rs25531 (A/G) | SNP within 5-HTTLPR | G allele frequency ~10% | Modifies L allele function; Lg allele behaves like S allele, reducing expression. |
| Ile425Val (rs28914832) | Missense variant | Rare (<0.1%) | Gain-of-function, increased serotonin uptake, associated with OCD and autism. |
| Pro339Leu (rs28914833) | Missense variant | Rare (<0.1%) | Loss-of-function, reduced transporter activity, linked to depression. |
Mutation functional classification
Loss of Function (LOF)
Variants such as Pro339Leu reduce serotonin reuptake, leading to increased synaptic serotonin; associated with depression and anxiety.
Gain of Function (GOF)
Variants such as Ile425Val increase transporter activity, reducing synaptic serotonin; linked to OCD and autism.
Dominant Negative (DN)
No well-characterized dominant-negative variants reported for SLC6A4.
View complete mutation data：
Gene Ontology (GO)
| • serotonin:proton symporter activity | • serotonin transmembrane transporter activity |
| • neurotransmitter:sodium symporter activity | • plasma membrane |
| • integral component of plasma membrane | • serotonin transport |
| • response to drug | • behavioral fear response |
Pathways
• Serotonergic synapse (KEGG: hsa04726)
• Neuroactive ligand-receptor interaction (KEGG: hsa04080)
• Serotonin transporter activity in depression (Reactome: R-HSA-442660)
Protein Summary
The SLC6A4 protein (UniProt P31645) is a 630-amino acid integral membrane protein with 12 transmembrane domains. It mediates the sodium- and chloride-dependent reuptake of serotonin, terminating serotonergic neurotransmission. The protein is glycosylated and forms homooligomers. It is expressed on neuronal presynaptic terminals, platelets, and enterocytes. Its activity is modulated by phosphorylation and interactions with accessory proteins. The transporter is the target of SSRIs and cocaine. Structural studies reveal a conserved neurotransmitter:sodium symporter fold.
Related Services
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| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SLC6A4 Knockout HEK293 Cell Line | EDJ-KQ2583 | Human | 6532 | Details Get a Quote |
| SLC6A4 Knockout HeLa Cell Line | EDJ-KQ54493 | Human | 6532 | Details Get a Quote |
| SLC6A4 Knockout A-549 Cell Line | EDJ-KQ62979 | Human | 6532 | Details Get a Quote |
| SLC6A4 Knockout HCT 116 Cell Line | EDJ-KQ71450 | Human | 6532 | Details Get a Quote |
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