Biology of the postsynaptic glycine receptor

Glycine is one of the major inhibitory neurotransmitters, and upon binding to its receptor it activates chloride conductances. Receptors are accumulated immediately opposite release sites, at the postsynaptic differentiations, where they form functional microdomains. This review describes recent advances in our understanding of the structure-function relationships of the glycine receptor, a member of the ligand-gated ion channel superfamily. Following purification of the receptor complex and identification of its integral and peripheral membrane protein components, molecular cloning has revealed the existence of several subtypes of the ligand-binding subunit. This heterogeneity is responsible for the distinct pharmacological and functional properties displayed by the various receptor configurations that are differentially expressed and assembled during development. This review also focuses on the molecular aspects of glycinergic synaptogenesis, highlighting gephyrin, the peripheral component of the receptor. The role of this cytoplasmic protein in anchoring and maintaining the channel complex in postsynaptic clusters is discussed. The glycine receptor recently moved into the spotlight as a paradigm in the approach to cell biology of the formation of the postsynaptic membrane.