The role of chloride ions on the transport of glycine in plasma membrane vesicles from glial cells

Abstract

The high-affinity transport system for glycine in plasma membrane vesicles from C6 glioma cells is dependent on Na + and also on the presence of Cl − in the incubation medium. This anion requirement is relatively specific for Cl −, since other anions are also capable of stimulating the glycine transport in the following order of decreasing efficacy: Cl − >Br − >SCN − ≅I − >NO 3 − >F −. Chloride ions raise the V max for transport and, to a lesser extent, act on the K m. The data provided by direct measurements of the coupling of sodium and chloride to the transport of glycine by using a kinetic approach suggest a stoichiometry for the translocation cycle catalyzed by the glycine transporter of two sodium ions and one chloride ion per glycine zwitterion.