title: Influence of sodium and sulphydryl groups on [3H]sulpiride binding sites in rat striatal membranes.
abstract: The effect of thiol reagents on the specific binding of the atypical neuroleptic, sulpiride, to rat striatal membranes are examined. Pretreatment of membranes with N-ethylmaleimide (NEM), but not with iodoacetamide or dithiothreitol (DTT), diminishes [3H]sulpiride binding. The effect is dependent on time, temperature, and the concentration of NEM. The reaction proceeds with pseudo-first-order rate kinetics, indicating the involvement of a single essential SH group in the binding of [3H]sulpiride to striatal membranes sites. Both sodium and sulpiride, but not nucleotides, protect the [3H]sulpiride sites from NEM inactivation in a dose-dependent fashion. As sodium is essential for [3H]sulpiride binding it is possible that in the presence of sodium and sulpiride a conformational change takes place that makes the essential SH group less accessible to alkylation.
mesh_terms: D000818:Animals; D001665:Binding Sites; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D004229:Dithiothreitol / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism; D005033:Ethylmaleimide / Q000494:pharmacology; D006150:Guanine Nucleotides / Q000494:pharmacology; D051381:Rats; D012964:Sodium / Q000494:pharmacology*; D013439:Sulfhydryl Reagents / Q000494:pharmacology*; D013469:Sulpiride / Q000378:metabolism*
chemical_list: D006150:Guanine Nucleotides; D013439:Sulfhydryl Reagents; D013469:Sulpiride; D012964:Sodium; D005033:Ethylmaleimide; D004229:Dithiothreitol; D004298:Dopamine