| Modification Notes |
In the central nervous system (CNS), glycine-mediated inhibitory neurotransmission is essential to voluntary motor control and reflex responses. Glycine binds to glycine receptors (GlyR) in the post synaptic neuronal membranes. GlyR, ©-aminobutryic acid, serotonin and acetylcholine comprise an evolutionally conserved superfamily of ligand-gated ion channels. The pentameric subunit structure of GlyR consists of two types of glycosylated membrane proteins, å1 through å4 and ∫, and an associated peripheral membrane protein, which combine to form a chloride-selective ion channel. In humans, the composition of the pentamer changes from å2 subunits in the fetal CNS to å1 and ∫ subunits in the adult CNS. Fast potentiation of GlyR by intracellular Ca2+ in the brainstem and midbrain indicate an important role for Ca2+ in modulation glycinergic synapses. The genes encoding human GlyR å1, å2, å3 and ∫ subunits map to chromosomes 5q32, Xp22, 4q33 and 4q31, respectively. |