标题：Distinct protein components from Torpedo marmorata membranes carry the acetylcholine receptor site and the binding site for local anesthetics and histrionicotoxin
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1978
卷号：75
期号：1
页码：510-514
DOI：10.1073/pnas.75.1.510
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Highly purified subsynaptic membrane fragments prepared from Torpedo marmorata electric organ (specific activity, greater than 4 mumol of Naja nigricollis alpha-[3H]toxin per mg of protein) exhibit, on sodium dodecyl sulfate/polyacrylamide gel electrophoresis, two major protein bands of apparent molecular weight 40,000 and 43,000, respectively. Dissolution of these membranes by the nondenaturing detergents Triton X-100 and Berol 043 followed by standard fractionation yielded (i) the 9S acetylcholine-receptor protein which still binds the alpha-[3H]toxin and after further purification yielded, in the presence of sodium dodecyl sulfate, the 40,000-dalton component, covalently labeled by the affinity reagent 4-(N-maleimido)phenyl[3H]trimethylammonium; only serine was found as the NH2-terminal amino acid of this protein; and (ii) a high molecular weight aggregate named 43,000 protein which was resolved in denaturing gels almost exclusively as the 43,000-dalton band, In the absence of detergents, the 43,000 protein binds compounds known to interact with the acetylcholine ionophore: a fluorescent local anesthetic quinacrine and histrionicotoxin (apparent dissociation constant, 7 +/- 1 X 10(-7) M). The regulation of quinacrine fluorescennce by carbamylcholine, observed in the intact membrane, no longer occurs with the isolated 43,000 component.
