Glycine and Proline Transporters

Apart from its obvious biochemical functions, glycine is also an important inhibitory neurotransmitter. Following depolarization, glycine is released from synaptic vesicles, binds to glycine receptors (GlyRs) on postsynaptic membranes thereby causing hyperpolarization of postsynaptic neurons due to the massive influx of Cl ions. Glycine is then taken up from the synaptic cleft via the glycine transporters GlyT1 and GlyT2. Proline Transporter (PROT) belongs to a gene family of high affinity Na+– and Cl-dependent plasma membrane transporters. PROT is a glycosylated protein encoded by the Slc6a7 gene. Its structure contains 12 putative transmembrane domains and is enriched in synaptosomal membrane fraction.