Modulation of the dopamine transporter by interaction with Secretory Carrier Membrane Protein 2.

The monoamine transporters for dopamine (DAT), norepinephrine (NET) and serotonin (SERT) facilitate the homeostatic balance of neurotransmitters in the synaptic cleft and thus, play a fundamental role in regulating neuronal activity. Despite the importance of these monoamine transporters in controlling brain function, only relatively little information is available regarding the cellular and molecular regulation of these proteins. The monoamine transporters have been found to associate with a number of different proteins that regulate the function and subcellular localization of the transporters. We recently reported a functional interaction between SERT and the Secretory Carrier Membrane Protein 2 (SCAMP2). Here, we demonstrate that SCAMP2 also plays a role in the functional regulation of DAT. DAT and SCAMP2 interaction is here verified by co-immunoprecipitation and fluorescence resonance energy transfer (FRET) microscopy. Moreover, co-expression of DAT and SCAMP2 results in a decrease in DAT-mediated dopamine uptake caused by reduced levels of DAT molecules on the cell surface. Our finding that SCAMP2 interacts with and regulates the subcellular distribution of both DAT and SERT suggests that interaction with SCAMP2 may constitute an important mechanism for coordinating cell surface expression of monoamine transporters.