Taurine binding by rat retinal membranes.
Retinal membrane preparations contain endogenous taurine which is difficult to remove. By repeatedly washing the membranes in buffer the taurine content was reduced from 11.7 +/- 2.5 to 2.5 +/- 0.5 nmol/mg protein. However, complete elimination of the endogenous taurine from the membrane preparation was not achieved. Binding of [3H]-taurine to rat retinal membrane preparations revealed both high and low affinity binding sites. A Hill coefficient of 0.71 suggested that cooperativity may be involved in the taurine binding process. Taurine binding was sodium dependent with maximum binding achieved at 118 mM. At suboptimal concentrations of sodium ions (30 mM) only one binding site was observed which appears to be the high affinity binding site. Analogues of taurine were tested for their effectiveness in displacing taurine from its binding site. Hypotaurine, beta-alanine, gamma-aminobutyric acid, and guanidinoethanesulfonic acid were the most potent displacers.
D000818:Animals; D001665:Binding Sites; D007700:Kinetics; D008566:Membranes / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D012160:Retina / Q000378:metabolism* / Q000648:ultrastructure; D012964:Sodium / Q000378:metabolism; D013654:Taurine / Q000037:antagonists & inhibitors / Q000378:metabolism*
D013654:Taurine; D012964:Sodium