Glycine neurotransmitter transporters: an update

Glycine accomplishes several functions as a transmitter in the central nerv ous system (CNS). As an inhibitory neurotransmitter, it participates in the processing of motor and sensory information that permits movement, vision, and audition. This action of glycine is mediated by the strychnine-sensiti ve glycine receptor, whose activation produces inhibitory post-synaptic pot entials. In some areas of the CNS, glycine seems to be co-released with GAB A, the main inhibitory amino acid neurotransmitter. In addition, glycine mo dulates excitatory neurotransmission by potentiating the action of glutamat e at N-methyl-D-aspartate (NMDA) receptors. It is believed that the termina tion of the different synaptic actions of glycine is produced by rapid reup take through two sodium-and-chloride-coupled transporters, GLYT1 and GLYT2, located in the plasma membrane of glial cells or pre-synaptic terminals, r espectively. Glycine transporters may become major targets for therapeutic of pathological alterations in synaptic function. This article reviews rece nt progress on the study of the molecular heterogeneity, localization, func tion, structure, regulation and pharmacology of the glycine transporter pro teins.