INTERACTION OF TAURINE, GABA AND GLUTAMIC ACID WITH SYNAPTIC MEMBRANES

— Sodium‐independent but calcium‐dependent binding of taurine, GABA and glutamate to synaptic membranes from calf brain cortex is demonstrated. Binding constants of 1.5 μm for taurine, 46 μm for GABA and 45 μm for glutamate were obtained, being largely mixed with transport constants derived from the influx to empty membrane‐pouches (particularly in the case of GABA and glutamate), and in the case of GABA also with the non‐specific binding. Certain structural analogues of amino acids inhibited the binding, aspartate being the most potent inhibitor for glutamate, and β‐alanine for GABA and taurine, but KCN and 2,4‐dinitrophenol had no effect. The membrane‐attached [35S]taurine was divided by differential elution into easily extractable and firmly bound components.