2981097

Solubilization and detergent effects on interactions of some drugs and insecticides with the t-butylbicyclophosphorothionate binding site within the gamma-aminobutyric acid receptor-ionophore complex.

Article date: 1985/1/1

PubMed ID: 2981097

Journal name: Journal of neurochemistry (ISSN: 0022-3042)

ABSTRACT

Specific binding of [35S]t-butylbicyclophosphorothionate (TBPS) to rat brain membranes (RBM) is enhanced nine-fold by EDTA/water dialysis and 1.3- to 4.2-fold by 50 nM ketosteroid R 5135, or 5 mM 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) or related piperazine-N-alkanesulfonate buffers, or extensive washing with NaCl/Na phosphate or Na phosphate/citrate solution. About one-fifth of the [35S]TBPS binding capacity appears in the soluble fraction whereas the rest remains in particulate form on treatment of the EDTA/water-dialyzed RBM with 20 mM CHAPS. Similar KD values (64-86 nM) are obtained for the original EDTA/water-dialyzed membranes and the CHAPS-treated and/or -solubilized preparations. The Bmax of the EDTA-treated RBM is reduced five-fold on solubilization with CHAPS. The potency for displacement of [35S]TBPS changes in the presence of CHAPS or on CHAPS solubilization: gamma-aminobutyric acid (GABA) and muscimol inhibit specific [35S]TBPS binding more strongly in the absence than in the presence of CHAPS: TBPS, picrotoxinin, and photoheptachlor epoxide are almost equally active with RBM, RBM + CHAPS, and RBM solubilized with CHAPS. Levels of (1R, alpha S)-cis-cypermethrin and dimethylbutylbarbiturate which are inhibitory with RBM are moderately stimulatory after TBPS receptor solubilization. Thus CHAPS defines three regions of the GABA receptor-ionophore complex, i.e., the GABA and benzodiazepine receptors, the TBPS/picrotoxinin/polychlorocycloalkane receptor(s), and the sites at which the alpha-cyano pyrethroid and the barbiturate interact with TBPS binding.

This document is available from: http://directlinks.cc/files/muscimol/2981097.pdf

Author List: Seifert J, Casida J E

Publication Types: Journal Article; Research Support, U.S. Gov't, P.H.S.

Substances mentioned in the article: Bridged Bicyclo Compounds; Bridged Bicyclo Compounds, Heterocyclic; Bridged-Ring Compounds; Cholic Acids; Receptors, GABA-A; polidocanol; Polyethylene Glycols; tert-butylbicyclophosphorothionate; Edetic Acid; 3-((3-cholamidopropyl)dimethylammonium)-1-propanesulfonate;

Mesh terms: Animals; Binding Sites; Brain/metabolism; Bridged Bicyclo Compounds/metabolism; Bridged Bicyclo Compounds, Heterocyclic; Bridged-Ring Compounds/metabolism; Cholic Acids/pharmacology; Edetic Acid/pharmacology; Kinetics; Male; Membranes/metabolism; Polyethylene Glycols/pharmacology; Rats; Receptors, GABA-A/metabolism; Solubility;

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