Agonist‐ and competitive antagonist‐induced movement of loop 5 on the α subunit of the neuronal α4β4 nicotinic acetylcholine receptor
Agonist‐ and competitive antagonist‐induced movement of loop 5 on the α subunit of the neuronal α4β4 nicotinic acetylcholine receptor
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激动剂â 和竞争性拮抗剂â 诱导神经元α4β4 烟碱乙酰胆碱受体α 亚基上环5 的运动
DOI：
10.1111/j.1471-4159.2007.05151.x
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发表时间：
2008
影响因子：
4.7
通讯作者：
Rettinger J
中科院分区：
文献类型：
--
作者：
Mourot A;Bamberg E;Rettinger J
神经元烟碱乙酰胆碱受体（nAChRs）是一种配体控制的离子通道，可快速将化学信号转化为电信号。虽然nAChR的结构已经被很好地描述，但激动剂结合和通道门控之间的耦合仍然存在争议。在本研究中，我们通过特异性地将构象敏感的荧光染料系在位于环5 （L5）的αG98C上，探测神经元α4β4 nAChR的局部构象转变，并同时监测在异种卵母细胞中表达后的荧光强度和电流。乙酰胆碱（ACh）的效力在半胱氨酸突变体中显著升高，在四甲基罗丹明- 6 -马来酰亚胺标记后进一步增加，表明L5在结合或门控中起作用。在乙酰胆碱暴露期间，荧光强度增加，表明L5在激活后发生结构重组。当乙酰胆碱浓度低于当前激活所需的浓度时，也检测到荧光变化，表明L5处于闭合、静止或脱敏状态。竞争拮抗剂二氢β红血碱也能诱导L5的运动，尽管其浓度明显高于当前抑制所需的浓度。因此，位于五聚体腔内的L5在nAChR的激活和抑制中都起作用。
Neuronal nicotinic acetylcholine receptors (nAChRs) are ligand‐gated ion channels that rapidly convert a chemical signal into an electrical signal. Although the structure of the nAChR is quite well described, the coupling between agonist binding and channel gating is still under debate. In this study, we probed local conformational transitions on the neuronal α4β4 nAChR by specifically tethering a conformation‐sensitive fluorescent dye on αG98C located on loop 5 (L5), and simultaneously monitoring fluorescence intensity and current after expression inXenopusoocytes. The potency of acetylcholine (ACh) was significantly higher in the cysteine mutant and further increased upon tetramethylrhodamine‐6‐maleimide labeling, suggesting a role of L5 in binding or gating. Structural reorganizations of L5 were shown to occur upon activation, as revealed by the fluorescence intensity increase during ACh exposure. Fluorescence changes were also detected at ACh concentrations lower than needed for current activation, suggesting a movement of L5 for a closed, resting or desensitized state. The competitive antagonist dihydro‐β‐erythroidine also induced a movement of L5 although at concentrations significantly higher than needed for current inhibition. Consequently L5, located inside the lumen of the pentamer, plays a role in both activation and inhibition of the nAChR.
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DOI：
10.1021/bi060222v
发表时间：
2006
期刊：
Biochemistry.
影响因子：
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作者：
Muroi,Yukiko;Czajkowski,Cynthia;Jackson,MeyerB
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DOI：
--
发表时间：
2006
期刊：
影响因子：
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作者：
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通讯作者：
R. Lukas
影响因子：
5.6
作者：
Unwin, N
通讯作者：
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DOI：
10.3390/v3040293
发表时间：
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期刊：
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影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
S. C. Harvey;F. Maddox;C. Luetje