Interaction of a spin-labeled long chain acylcholine with the cholinergic receptor protein in its membrane environment. |
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| Authors: | A D Brisson, C J Scandella, A Bienvenü e, P F Devaux, J B Cohen, J P Changeux |
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| Affiliation: | A D Brisson, C J Scandella, A Bienvenüe, P F Devaux, J B Cohen, and J P Changeux |
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| Abstract: | The choline ester of a spin-labeled fatty acid, 8-doxylpalmitocylcholine, CH3--(CH2)7--CR-(CH2)6-- + COO--(CH2)2--N(CH3)3, where R is the paramagnetic 4',4'-dimethyloxazolidine-N-oxyl (doxyl) ring has been synthesized. 8-Doxylpalmitoylcholine blocks reversibly the depolarization of Electrophorus electroplaque elicited by the bath application of carbamylcholine. It slows down the initial rate of binding of the alpha-[3-H]toxin from Naja nigricollis to receptor-rich membranes fragments from Torpedo, and it displaces [3-H]acetylcholine bound to the cholinergic receptor site present in these fragments. Electron spin resonance spectra of 8-doxylpalmitoylcholine in the presence of the receptor-rich membrane fragments show complete immobilization of the spin label. Various cholinergic agents tested, including N. nigricollis alpha-toxin, reverse this immobilization, probably by displacing the 8-doxylpalmitoylcholine from its complex with the cholinergic receptor protein to the lipid phase of the membrane. |
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