Inactivation of [ 35S]t-butylbicyclophosphorothionate binding sites by the arginine reagent, 2,3-butanedione

Abstract

The “cage” convulsant [ 35S]t-butylbicyclophosphorothionate ([ 35S]TBPS) binds with high affinity to specific sites “at” or “near” a γ-amino-butyric acid (GABA)-gated chloride channel according to current hypothesis. We now report that pretreatment of membranes with 2,3-butanedione, an arginine-specific reagent, causes a dose- and time-dependent decrease in the number of [ 35S]TBPS binding sites. No decrease occurs when membranes are pretreated with 2,3-butanedione in the presence of picrotoxinin. Binding of [ 35S]TBPS to the remaining sites occurs with the same characteristics as binding to the untreated receptor population.