Four pharmacologically distinct subtypes of α4β2 nicotinic acetylcholine receptor expressed in Xenopus laevis oocytes
Four pharmacologically distinct subtypes of α4β2 nicotinic acetylcholine receptor expressed in Xenopus laevis oocytes
复制标题
DOI：
10.1124/mol.54.6.1124
复制
发表时间：
1998-12-01
影响因子：
3.6
通讯作者：
Vijverberg, HPM
中科院分区：
文献类型：
--
作者：
Zwart, R;Vijverberg, HPM
烟碱受体通常被认为由两个α亚基和三个非α亚基组成。我们改变了非洲爪蟾卵母细胞中的神经元烟碱α 4和β 2受体亚基的相对表达水平，通过核注射编码这些亚基的cDNA，α：β比例为9：1，1：1和1：9。在电压钳实验中研究了受体对乙酰胆碱和d-筒箭毒碱的敏感性。对于以9：1和1：1 α：β比率表达的受体，乙酰胆碱的EC 50值类似于60 μ M。对于大多数以1：9 α：β比率表达的受体，对乙酰胆碱的敏感性增强30倍。没有证据表明，在一个单一的受体乙酰胆碱结合位点的一种以上的类型。对d-筒箭毒碱的敏感性随着α：β比率的降低而降低。d-筒箭毒碱的IC 50值分别为0.2、0.5和2 μ M，α：β比例为9：1、1：1和1：9。在1：9的α：β比率下，表达了IC 50值为163 μ M d-筒箭毒碱的另外的受体。需要至少两种对d-筒箭毒碱具有不同敏感性的组分来解释IC 50的变化。激动剂和拮抗剂的联合作用揭示了α 4 β 2烟碱受体的四种不同亚型。结果表明，异聚α 4 β 2乙酰胆碱受体的亚基化学计量不限于2 α：3 β。
Nicotinic receptors generally are presumed to consist of two alpha and three non-alpha subunits. We varied the relative levels of expression of the neuronal nicotinic alpha 4 and beta 2 receptor subunits in Xenopus laevis oocytes by nuclear injection of cDNAs coding for these subunits in alpha:beta ratios of 9:1, 1:1, and 1:9. The sensitivities of the receptors to acetylcholine and d-tubocurarine were investigated in voltage-clamp experiments. For receptors expressed at the 9:1 and 1:1 alpha:beta ratios, the EC50 value of acetylcholine is similar to 60 mu M. For the majority of the receptors expressed at the 1:9 alpha:beta ratio, the sensitivity to acetylcholine is enhanced 30-fold. No evidence for more than one type of acetylcholine binding site in a single receptor is obtained. The sensitivity to d-tubocurarine decreases with decreasing alpha:beta ratio. IC50 values of d-tubocurarine are 0.2, 0.5, and 2 mu M for the 9:1, 1:1, and 1:9 alpha:beta ratios, respectively. At the 1:9 alpha:beta ratio, additional receptors with an IC50 value of 163 mu M d-tubocurarine are expressed. At least two components with distinct sensitivities to d-tubocurarine are required to account for the shift in IC50. The combined agonist and antagonist effects reveal four distinct subtypes of alpha 4 beta 2 nicotinic receptors. The results imply that the subunit stoichiometry of heteromeric alpha 4 beta 2 acetylcholine receptors is not restricted to 2 alpha:3 beta.