Functional α6-containing nicotinic receptors are present in chick retina
Functional α6-containing nicotinic receptors are present in chick retina
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DOI：
10.1124/mol.56.1.11
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发表时间：
1999-07-01
影响因子：
3.6
通讯作者：
Gotti, C
中科院分区：
文献类型：
--
作者：
Vailati, S;Hanke, W;Gotti, C
尽管神经小鸡α 6亚基在几年前被首次克隆，并且最近被证明在异源系统中形成乙酰胆碱（ACh）激活的通道，但关于神经元组织中含有α 6的烟碱受体的结构和功能尚无信息。利用针对鸡α 6亚基两种不同表位的亚基特异性抗体，我们对含有烟碱激动剂[H-3]依比替丁（Epi）放射标记的免疫纯化α 6受体进行了免疫沉淀实验：几乎所有α 6受体都含有β 4亚基，β 3亚基为51%，α 3亚基为42%，β 2亚基为7.5%。纯化受体的Western blot分析证实了α 3、β 3、β 2和β 4亚基的存在，而α 4、α 5和α 7亚基的缺失。含有α 6的受体结合[H-3]Epi （K-d = 35 pM）和其他一些尼古丁激动剂具有非常高的亲和力，等级顺序为Epi >> cytisine >尼古丁b> 1,1-二甲基-4-苯基哌嗪>乙酰胆碱>氨甲酰胆碱。α 6受体也具有明显的拮抗剂药理学特征，其效力顺序为α - concontoxin MII > methyllycaconitine >二氢- β -红血素> MG624 > d-tubocurarine >十甲基溴>六甲基溴。当在脂质双层中重组时，含有α 6的受体形成功能阳离子通道，其主要电导状态为48 pS。这些通道被烟碱激动剂以剂量依赖的方式激活，并被烟碱拮抗剂d-管碱阻断。
Despite the fact that the neuronal chick alpha 6 subunit was first cloned several years ago and recently has been shown to form acetylcholine (ACh)-activated channels in heterologous systems, no information is yet available concerning the structure and function of the alpha 6-containing nicotinic receptors in neuronal tissues. Using subunit-specific antibodies directed against two different epitopes of the chick alpha 6 subunit, we performed immunoprecipitation experiments on immunopurified alpha 6-containing receptors radiolabeled with the nicotinic agonist [H-3]epibatidine (Epi): almost all of the alpha 6 receptors contained the beta 4 subunit, 51% the beta 3 subunit, 42% the alpha 3 subunit, and 7.5% the beta 2 subunit. Western blot analyses of the purified receptors confirmed the presence of the alpha 3, beta 3, beta 2, and beta 4 subunits, and the absence of the alpha 4, alpha 5, and alpha 7 subunits. The alpha 6-containing receptors bind [H-3]Epi (K-d = 35 pM) and a number of other nicotinic agonists with very high affinity, the rank order being Epi >> cytisine > nicotine > 1,1-dimethyl-4-phenylpiperazinium > acetylcholine > carbamylcholine. The alpha 6 receptors also have a distinct antagonist pharmacological profile with a rank order of potency of alpha-conotoxin MII > methyllycaconitine > dihydro-beta-erythroydine > MG624 > d-tubocurarine > decamethonium > hexamethonium. When reconstituted in lipid bilayers, the alpha 6-containing receptors form functional cationic channels with a main conductance state of 48 pS. These channels are activated by nicotinic agonists in a dose-dependent manner, and blocked by the nicotinic antagonist d-tubocurarine.