Neurotransmitter sodium symporters (NSS) are targets for anti-depressants, psychostimulants and other drugs.
[4] The generalized transport reaction for the members of this family is:[2] The family has a common structure of 12 presumed transmembrane helices and includes carriers for gamma-aminobutyric acid (GABA), noradrenaline/adrenaline, dopamine, serotonin, proline, glycine, choline, betaine, taurine and other small molecules.
[8] Tavoulari et al. (2011) described conversion of the Cl− -independent prokaryotic tryptophan transporter TnaT (2.A.22.4.1) to a fully functional Cl− -dependent form by a single point mutation, D268S.
Mutations in TnaT-D268S, in wild type TnaT and in a serotonin transporter (SERT; 2.A.22.1.1) provided direct evidence for the involvement of each of the proposed residues in Cl− coordination.
In both SERT and TnaT-D268S, Cl− and Na+ mutually increase each other's potency, consistent with electrostatic interaction through adjacent binding sites.