Cloning and expression of a high affinity taurine transporter from rat brain.

A cDNA clone (designated rB16a) encoding a taurine transporter has been isolated from rat brain, and its functional properties have been examined in mammalian cells. The nucleotide sequence of the clone predicts a 621-amino acid protein with significant homology to other neurotransmitter transporters. Hydropathy analysis reveals stretches of hydrophobic amino acids indicative of 12 transmembrane domains, similar to those proposed for other cloned neurotransmitter transporters. The transporter displays high affinity for taurine (Km approximately 40 microM) and is dependent on external sodium and chloride for transport activity. Specific transport is sensitive to inhibition by beta-alanine and gamma-aminobutyric acid, similar to taurine transporters in vivo. Localization studies demonstrate that the transporter mRNA is located in both the brain and peripheral tissues. The structural similarity of the taurine transporter to neurotransmitter transporters is consistent with a neuromodulatory role for taurine in the nervous system.