Oswald R, Changeux J P
Proc Natl Acad Sci U S A. 1981 Jun;78(6):3925-9. doi: 10.1073/pnas.78.6.3925.
Reversible ligands were attached covalently to membrane-bound acetylcholine receptor from Torpedo marmorata by a method which is generally applicable and does not require the synthesis of specially designed molecules. UV irradiation of the receptor in the presence of [3H]trimethisoquin, [3H]phencyclidine, or [3H]perhydrohistrionicotoxin resulted in the labeling of the binding site(s) for these noncompetitive blockers of the permeability response. The labeling of the delta chain was enhanced by carbamoylcholine, and this increase was blocked by snake alpha-toxins. The effect of carbamoylcholine on [3H]trimethisoquin binding was more pronounced than with the other two noncompetitive blockers; in all instances, the labeling was abolished by unlabeled histrionicotoxin. These three compounds therefore interact with the high-affinity site for noncompetitive blockers. Incorporation of radioactivity also occurred into the alpha chain but either was insensitive to cholinergic effectors or decreased in the presence of carbamoylcholine (or snake alpha-toxin), probably as a result of an interaction with the acetylcholine-binding site. In contrast to the other noncompetitive blockers tested, [3H]chlorpromazine heavily labeled the four receptor polypeptides (alpha, beta, gamma, delta), and this labeling also was enhanced by carbamoylcholine and decreased by histrionicotoxin. These data indicate a contribution of the delta chain to the binding site(s) of several well-characterized noncompetitive blockers and suggest that other receptor polypeptides may also contribute to this binding.
通过一种普遍适用且无需合成特殊设计分子的方法，将可逆配体共价连接到电鳐的膜结合型乙酰胆碱受体上。在[³H]三甲异喹、[³H]苯环利定或[³H]全氢组氨酰毒蕈碱存在的情况下，对受体进行紫外线照射，会导致这些通透性反应的非竞争性阻滞剂的结合位点被标记。氨基甲酰胆碱增强了δ链的标记，而这种增加被蛇α毒素阻断。氨基甲酰胆碱对[³H]三甲异喹结合的影响比其他两种非竞争性阻滞剂更为明显；在所有情况下，未标记的组氨酰毒蕈碱可消除标记。因此，这三种化合物与非竞争性阻滞剂的高亲和力位点相互作用。放射性也掺入了α链，但要么对胆碱能效应物不敏感，要么在氨基甲酰胆碱（或蛇α毒素）存在时减少，这可能是与乙酰胆碱结合位点相互作用的结果。与测试的其他非竞争性阻滞剂不同，[³H]氯丙嗪大量标记了四种受体多肽（α、β、γ、δ），这种标记也被氨基甲酰胆碱增强，并被组氨酰毒蕈碱减少。这些数据表明δ链对几种特征明确的非竞争性阻滞剂的结合位点有贡献，并表明其他受体多肽可能也对这种结合有贡献。
