title: Interaction of a spin-labeled long chain acylcholine with the cholinergic receptor protein in its membrane environment.
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.
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D002217:Carbachol; D002794:Choline / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D003497:Cyclic N-Oxides / Q000378:metabolism*; D004557:Electric Organ / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D005399:Fishes; D008564:Membrane Potentials / Q000187:drug effects; D010080:Oxazoles / Q000378:metabolism; D010169:Palmitic Acids / Q000378:metabolism* / Q000494:pharmacology; D011485:Protein Binding; D011950:Receptors, Cholinergic; D012910:Snake Venoms; D013113:Spin Labels; D014118:Toxins, Biological / Q000378:metabolism
chemical_list: D003497:Cyclic N-Oxides; D010080:Oxazoles; D010169:Palmitic Acids; D011950:Receptors, Cholinergic; D012910:Snake Venoms; D013113:Spin Labels; D014118:Toxins, Biological; C010135:8-doxylpalmitoylcholine; D002217:Carbachol; D002794:Choline; D000109:Acetylcholine