D2 autoreceptor when activated; i.e., it internalizes dopamine transporters and induces efflux through reversed transporter function via PKA and PKC signaling. Surprisingly, DAT was not identified within any synaptic active zones. These results suggest that striatal dopamine reuptake may occur outside of synaptic specializations once dopamine diffuses from the synaptic cleft. In the substantia nigra, DAT is localized to axonal and dendritic (i.e., pre- and post-synaptic) plasma membranes. Within the perikarya of pars compacta neurons, DAT was localized primarily to rough and smooth endoplasmic reticulum, Golgi complex, and multivesicular bodies, identifying probable sites of synthesis, modification, transport, and degradation. Genetics and regulation The gene for DAT, known as DAT1, is located on chromosome 5p15. The protein encoding region of the gene is over 64 kb long and comprises 15 coding segments or exons. This gene has a variable number tandem repeat (VNTR) at the 3’ end (rs28363170) and another in the intron 8 region. Differences in the VNTR have been shown to affect the basal level of expression of the transporter; consequently, researchers have looked for associations with dopamine-related disorders. Nurr1, a nuclear receptor that regulates many dopamine-related genes, can bind the promoter region of this gene and induce expression. This promoter may also be the target of the transcription factor Sp-1. While transcription factors control which cells express DAT, functional regulation of this protein is largely accomplished by kinases. MAPK, CAMKII, PKA, and PKC can modulate the rate at which the transporter moves dopamine or cause the internalization of DAT. Co-localized TAAR1 is an important regulator of the dopamine transporter that, when activated, phosphorylates DAT through protein kinase A (PKA) and protein kinase C (PKC) signaling. Phosphorylation by either protein kinase can result in DAT internalization ( reuptake inhibition), but phosphorylation alone induces reverse transporter function (dopamine efflux). Dopamine autoreceptors also regulate DAT by directly opposing the effect of TAAR1 activation. The human dopamine transporter (hDAT) contains a high affinity extracellular zinc binding site which, upon zinc binding, inhibits dopamine reuptake and amplifies amphetamine-induced dopamine efflux in vitro. In contrast, the human serotonin transporter (hSERT) and human norepinephrine transporter (hNET) do not contain zinc binding sites. Zinc supplementation may reduce the minimum effective dose of amphetamine when it is used for the treatment of attention deficit hyperactivity disorder. Biological role and disorders The rate at which DAT removes dopamine from the synapse can have a profound effect on the