MOLECULAR-BIOLOGY OF GLYCINERGIC NEUROTRANSMISSION

Glycine is a major inhibitory neurotransmitter in the spinal cord and brainstem of vertebrates. Glycine is accumulated into synaptic vesicle s by a proton-coupled transport system and released to the synaptic cl eft after depolarization of the presynaptic terminal. The inhibitory a ction of glycine is mediated by pentameric glycine receptors (GlyR) th at belong to the ligand-gated ion channel superfamily. The synaptic ac tion of glycine is terminated by two sodium-and chloride-coupled trans porters, GLYT1 and GLYT2, located in the glial plasma membrane and in the presynaptic terminals, respectively. Dysfunction of inhibitory gly cinergic neurotransmission is associated with several forms of inherit ed mammalian myoclonus. In addition, glycine could participate in exci tatory neurotransmission by modulating the activity of the NMDA subtyp e of glutamate receptor. In this article, we discuss recent progress i n our understanding of the molecular mechanisms that underlie the phys iology and pathology of glycinergic neurotransmission.