Moore W M, Brady R N
Biochim Biophys Acta. 1976 Aug 24;444(1):252-60. doi: 10.1016/0304-4165(76)90242-7.
Specific binding of 125I-labeled alpha-bungarotoxin to a 34800 X g pellet of a whole rat brain homogenate has been obtained at levels of 2 pmol toxin per g of whole brain with a Kd of 8-10(-9) M. Binding is reduced 90% by 10(-5) M (+)-tubocurarine chloride and 10(-4) M nicotine, whereas concentrations of 10(-4) M choline chloride, atropine sulfate and eserine sulfate have essentially no effect on toxin binding. These results compare closely with those obtained from binding studies with 125I-labeled alpha-bungarotoxin and soluble acetylcholine receptor protein preparations from Torpedo nobiliana; suggesting that this mammalian receptor protein is nicotinic in character. Extraction of the 34800 X g pellet with 1% Emulphogene yields a soluble fraction with specifically binds 125I-labeled alpha-bungarotoxin with a Kd of 5-10(-9) M. Nicotine and alpha-bungarotoxin at concentrations of 10(-5) M abolish toxin-receptor complex formation and carbachol and (+)-tubocurarine chloride reduce complex formation 35-40% at similar concentrations. Eserine sulfate, atropine sulfate, decamethonium, and pilocarpine had no effect on complex formation at concentrations of 10(-5) M.
125I标记的α-银环蛇毒素与全大鼠脑匀浆34800×g沉淀的特异性结合已被证实，每克全脑结合2 pmol毒素，解离常数Kd为8×10⁻⁹ M至10×10⁻⁹ M。10⁻⁵ M的（+）-氯化筒箭毒碱和10⁻⁴ M的尼古丁可使结合减少90%，而10⁻⁴ M的氯化胆碱、硫酸阿托品和硫酸毒扁豆碱对毒素结合基本无影响。这些结果与用125I标记的α-银环蛇毒素和来自高贵枪乌贼的可溶性乙酰胆碱受体蛋白制剂进行结合研究所得结果非常相似；表明这种哺乳动物受体蛋白具有烟碱样特性。用1%乳化剂提取34800×g沉淀可得到一个可溶性部分，它能特异性结合125I标记的α-银环蛇毒素，Kd为5×10⁻⁹ M至10×10⁻⁹ M。10⁻⁵ M浓度的尼古丁和α-银环蛇毒素可消除毒素-受体复合物的形成，并在类似浓度下，卡巴胆碱和（+）-氯化筒箭毒碱可使复合物形成减少35%至40%。10⁻⁵ M浓度的硫酸毒扁豆碱、硫酸阿托品、十烃季铵和毛果芸香碱对复合物形成无影响。
