SLC6A4

The serotonin transporter (SERT or 5-HTT) also known as the sodium-dependent serotonin transporter and solute carrier family 6 member 4 is a protein that in humans is encoded by the SLC6A4 gene. SERT is a type of monoamine transporter protein that transports serotonin from the synaptic cleft to the presynaptic neuron.

This transport of serotonin by the SERT protein terminates the action of serotonin and recycles it in a sodium-dependent manner. This protein is the target of many antidepressant medications of the SSRI and Tricyclic antidepressant classes. It is a member of the sodium:neurotransmitter symporter family. A repeat length polymorphism in the promoter of this gene has been shown to affect the rate of serotonin uptake and may play a role in sudden infant death syndrome, aggressive behavior in Alzheimer disease patients, post-traumatic stress disorder and depression-susceptibility in people experiencing emotional trauma.

Serotonin-Reuptake transporters are dependent on both the concentration of potassium ion in the cytoplasm and the concentrations of sodium and chloride ions in the extracellular fluid. In order to function properly the Serotonin Transporter requires the membrane potential created by the sodium-potassium adenosine triphosphatase.

The Serotonin Transporter first binds a sodium ion, followed by the Serotonin, and then a chloride ion, thus it is allowed, thanks to the membrane potential, to flip inside the cell freeing all the elements previously bound. Right after the release of the Serotonin in the cytoplasm a potassium ion binds to the transporter which is now able to flip back out returning to its active state.

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