Multiple determinants of dihydro-beta-erythroidine sensitivity on rat neuronal nicotinic receptor alpha subunits.
Multiple determinants of dihydro-beta-erythroidine sensitivity on rat neuronal nicotinic receptor alpha subunits.
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发表时间：
1996
影响因子：
4.7
通讯作者：
S. C. Harvey;F. Maddox;C. Luetje
中科院分区：
文献类型：
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作者：
S. C. Harvey;F. Maddox;C. Luetje
神经元烟碱乙酰胆碱受体对竞争性拮抗剂二氢-β-赤藓定的阻断敏感性差异。α和β亚基都参与决定对这种拮抗剂的敏感性。通过比较α 4 β 4受体和α 3 β 4受体来说明α亚基对二氢-β-赤藓碱敏感性的贡献，α 4 β 4受体和α 3 β 4受体对二氢-β-赤藓碱的敏感性相差约120倍。阻断α 4 β 4和α 3 β 4的IC 50值，响应于乙酰胆碱的EC 20浓度，分别为0.19 +/- 0.06和23.1 +/- 10.2 μ M。为了定位导致这种差异的序列片段，我们构建了一系列含有α 4和α 3亚基部分的嵌合α亚基。这些嵌合体与β 4共表达，允许药理学表征。我们发现，二氢-β-erythroidine敏感性的决定因素分布在整个N-末端的α亚基的胞外结构域。这些决定簇定位于序列片段1-94、94-152和195-215。片段1-94内的决定簇的丢失具有最大的影响，使二氢-β-赤藓定的敏感性降低4.3倍。
Neuronal nicotinic acetylcholine receptors are differentially sensitive to blockade by the competitive antagonist dihydro-beta-erythroidine. Both alpha and beta subunits participate in determining sensitivity to this antagonist. The alpha subunit contribution to dihydro-beta-erythroidine sensitivity is illustrated by comparing the alpha 4 beta 4 receptor and the alpha 3 beta 4 receptor, which differ in sensitivity to dihydro-beta-erythroidine by approximately 120-fold. IC50 values for blocking alpha 4 beta 4 and alpha 3 beta 4, responding to EC20 concentrations of acetylcholine, were 0.19 +/- 0.06 and 23.1 +/- 10.2 microM, respectively. To map the sequence segments responsible for this difference, we constructed a series of chimeric alpha subunits containing portions of the alpha 4 and alpha 3 subunits. These chimeras were coexpressed with beta 4, allowing pharmacological characterization. We found determinants of dihydro-beta-erythroidine sensitivity to be distributed throughout the N-terminal extracellular domain of the alpha subunit. These determinants were localized to sequence segments 1-94, 94-152, and 195-215. Loss of determinants within segment 1-94 had the largest effect, decreasing dihydro-beta-erythroidine sensitivity by 4.3-fold.