Molecular characterization of the dopamine transporter.
Neurotransmission, which represents chemical signalling between neurons, usually takes place at highly differentiated anatomical structures called synapses. To fulfill both the time and space confinements required for optimal neurotransmission, highly specialized proteins, known as transporters or uptake sites, occur and operate at the presynaptic plasma membrane. Using the energy provided by the Na+ gradient generated by the Na+/K(+)-transporting ATPase, these transporters reuptake the neurotransmitters soon after their release, thereby regulating their effective concentrations at the synaptic cleft and the availability of neurotransmitters for a time-dependent activation of both pre- and postsynaptic receptors. The key role these proteins play in normal neurotransmission is further emphasized when the physiological and social consequences of drugs that interfere with the function of these transporters, such as the psychostimulants (e.g. amphetamine and cocaine) or the widely prescribed antidepressant drugs, are considered. In this review, Bruno Giros and Marc Caron elaborate on the potential consequences of the recent molecular cloning of the dopamine and related transporters and summarize some of the interesting properties that are emerging from this growing family of Na(+)- and Cl(-)-dependent transporters.