Properties of sodium-independent taurine binding to brain synaptic membranes

The sodium-independent taurine binding to twice Triton treated brain membranes characterized here was reversible, temperature-insensitive and saturable with a broad pH optimum, being thus characteristic of a synaptic receptor site. Only one type of binding site with a rather low maximal capacity was detected. Furthermore, binding exhibited properties of positive cooperativity, indicating that two or more taurine molecules possibly interact at a binding site. Both GABA and glycine as well as their agonists and antagonists strongly displaced taurine binding. The novel anticonvulsive taurine derivatives wee also effective displacers. The relevance of the binding observed in vitro to the possible synaptic receptors for taurine in vivo still remains to be determined.