5-hydroxytryptamine transporter (SERT) (SERT)

The 5-hydroxytryptamine transporter (SERT), encoded by the SLC6A4 gene, is a sodium- and chloride-dependent integral membrane protein responsible for the reuptake of serotonin (5-HT) from the extracellular space into presynaptic neurons [UniProt, 2025]. This reuptake mechanism is the primary regulator of the intensity and duration of serotonergic signaling within the central nervous system, as well as in peripheral tissues like the gastrointestinal tract and blood platelets [NCBI, 2025; Basicmedical Key, 2016]. In the periphery, SERT activity determines the amount of serotonin stored in platelets for coagulation and modulates gut motility [UniProt, 2025]. SERT is the principal target for several major classes of psychiatric medications, including selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs), which alleviate symptoms of depression and anxiety by increasing synaptic serotonin concentrations [Cureus, 2026]. Genetic variation in the SERT promoter region, particularly the 5-HTTLPR polymorphism, has been linked to individual differences in stress sensitivity and clinical response to these medications [NCBI, 2025]. Therapeutic use of SERT-targeting drugs requires careful management due to potential side effects like serotonin syndrome, sexual dysfunction, and impaired platelet function leading to increased bleeding risk [PubMed, 2021; Cureus, 2026].

Other names

Serotonin transporterSLC6A45-HTTHTTSolute carrier family 6 member 4Sodium-dependent serotonin transporter

Drugs targeting this transporter typically act as competitive inhibitors of the substrate binding site (e.g., most SSRIs) or as allosteric modulators (e.g., escitalopram), thereby blocking the reuptake of serotonin from the synaptic cleft and increasing its extracellular availability to postsynaptic receptors [NCBI, 2025; PubMed, 2016].