Single amino acid substitutions in α-conotoxin PnIA shift selectivity for subtypes of the mammalian neuronal nicotinic acetylcholine receptor
Single amino acid substitutions in α-conotoxin PnIA shift selectivity for subtypes of the mammalian neuronal nicotinic acetylcholine receptor
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DOI：
10.1074/jbc.274.51.36559
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发表时间：
1999-12-17
影响因子：
4.8
通讯作者：
Adams, DJ
中科院分区：
文献类型：
--
作者：
Hogg, RC;Miranda, LP;Adams, DJ
α-芋螺毒素是一类烟碱型乙酰胆碱受体（nAChR）拮抗剂，是研究不同nAChR亚型在细胞功能和通讯中所起作用的重要探针。在这项研究中，发现天然α-芋螺毒素PnIA和PnIB在所有大鼠副交感神经元中引起ACh诱导电流的浓度依赖性抑制，IC 50值分别为14和33 nM，电流幅度最大分别降低87%和71%。经修饰的α-芋螺毒素[N11 S]PnIA以375 nM的IC 50值降低ACh-诱导的电流，并且最大有效浓度引起91%的阻断，[A10 L]PnIA是最有效的抑制剂，在类似于80%的神经元中降低ACh-诱导的电流，IC 50值为1.4 nM，并且总电流的46%最大阻断，残余电流没有进一步抑制α-银环蛇毒素，但进一步减少铜芋螺毒素PnIA或PnIB，和美加明。1H-1 NMR研究表明PnIA、PnIB及其类似物[A10 L]PnIA和[N11 S]PnIA具有相同的骨架结构。我们建议，位置10和II的PnIA和PnIB的影响效力，并确定α 7和其他nAChR亚型，包括α 3 β 2和α 3 β 4之间的选择性，四个不同的组件的烟碱乙酰胆碱诱导的电流在哺乳动物副交感神经元已被解剖与这些conopeptides。
The alpha-conotoxins, a class of nicotinic acetylcholine receptor (nAChR) antagonists, are emerging as important probes of the role played by different nAChR subtypes in cell function and communication, In this study, the native alpha-conotoxins PnIA and PnIB were found to cause concentration-dependent inhibition of the ACh-induced current in all rat parasympathetic neurons examined, with IC50 values of 14 and 33 nM, and a maximal reduction in current amplitude of 87% and 71%, respectively. The modified alpha-conotoxin [N11S]PnIA reduced the ACh-induced current with an IC50 value of 375 nM and a maximally effective concentration caused 91% block, [A10L]PnIA was the most potent inhibitor, reducing the ACh-induced current in similar to 80% of neurons, with an IC50 value of 1.4 nM and 46% maximal block of the total current, The residual current was not inhibited further by alpha-bungarotoxin, but was further reduced by the cu-conotoxins PnIA or PnIB, and by mecamylamine. H-1 NMR studies indicate that PnIA, PnIB, and the analogues, [A10L]PnIA and [N11S]PnIA, have identical backbone structures. We propose that positions 10 and II of PnIA and PnIB influence potency and determine selectivity among alpha 7 and other nAChR subtypes, including alpha 3 beta 2 and alpha 3 beta 4, Four distinct components of the nicotinic ACh-induced current in mammalian parasympathetic neurons have been dissected with these conopeptides.