35S] tert.-butylbicyclophosphorothionate and avermectin bind to different sites associated with the γ-aminobutyric acid-benzodiazepine receptor complex

Abstract

Low concentrations of avermectin B 1a (AVM) stimulated the specific high affinity binding of [ 35S] tert.-butylbicyclophosphorothionate ([ 35S]TBPT) to membranes from rat cerebral cortex in the absence or presence of chloride or bromide ions. In contrast, TBPT either weakly stimulates or does not significantly influence the specific high affinity binding of [ 3H]AVM to the same membranes in the absence or presence of chloride ions, respectively. These results indicate that [ 3H]AVM and [ 35S]TBPT bind to different but closely associated binding sites.