Serotonin transporter whose primary function in the central nervous system involves the regulation of serotonergic signaling via transport of serotonin molecules from the synaptic cleft back into the pre-synaptic terminal for re-utilization. Plays a key role in mediating regulation of the availability of serotonin to other receptors of serotonergic systems. Terminates the action of serotonin and recycles it in a sodium-dependent manner. Monomer or homooligomer (PubMed:10716733). Interacts with TGFB1I1. Interacts with SEC23A, SEC24C and PATJ. Interacts with NOS1; the interaction may diminish the cell surface localization of SERT in the brain and, correspondingly, reduce serotonin reuptake (By similarity). Interacts (via C-terminus) with SCAMP2; the interaction is direct and retains transporter molecules intracellularly (PubMed:16870614). Interacts with filamentous actin and STX1A (PubMed:11709063). Interacts with ITGAV:ITGB3 (By similarity). Could be part of recycling endosomes (PubMed:16870614). Density of transporter molecules on the plasma membrane is itself regulated by STX1A (PubMed:11709063). Density of transporter molecules on the plasma membrane is also regulated by serotonin (By similarity). Density of transporter molecules seems to be modulated by ITGAV:ITGB3 (By similarity). Phosphorylation at Thr-276 increases 5-HT uptake and is required for cGMP-mediated SERT regulation. This protein is the target of psychomotor stimulants such as amphetamines or cocaine. Belongs to the sodium:neurotransmitter symporter (SNF) (TC 2.A.22) family. SLC6A4 subfamily. Reported to be glycosylated with sialylated N-glycans and in its sialylated form to interact with MYH9 (PubMed:12944413). However, this publication was retracted due to image duplication in the figures.