Cloning and expression of a glycine transporter reveal colocalization with NMDA receptors

A complementary DNA clone encoding a transporter for glycine has been isolated from rat brain, and its functional properties have been examined in mammalian cells. The transporter displays high affinity for glycine (KM approximately 100 microM) and is dependent on external Na+ and Cl-. Northern blot analysis indicates that the distribution of the mRNA encoding the glycine transporter is restricted to the nervous system. In situ hybridization data are consistent with roles for the transporter in both glycine neurotransmission and glycine modulation of N-methyl-D-aspartate (NMDA) receptors in the hippocampus. The identification of this transporter therefore opens the study of the molecular mechanisms underlying both inhibitory glycinergic transmission and NMDA-mediated excitatory transmission.