Properties of the human muscle nicotinic receptor, and of the slow‐channel myasthenic syndrome mutant εL221F, inferred from maximum likelihood fits
Properties of the human muscle nicotinic receptor, and of the slow‐channel myasthenic syndrome mutant εL221F, inferred from maximum likelihood fits
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人类肌肉烟碱受体和慢通道肌无力综合征突变体 εL221F 的特性，从最大似然拟合推断
DOI：
10.1111/j..2003.t01-1-00729.x
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
David Colquhoun
中科院分区：
文献类型：
--
作者：
C. Hatton;Chris Shelley;M. Brydson;David Beeson;David Colquhoun
利用人重组受体（包括野生型受体和含有慢通道肌无力综合征突变基因εL221F的受体）研究了尼古丁受体激活的机制。该方法使用HJCFIT程序，该程序将指定机制中的速率常数直接拟合到观察到的打开和关闭时间序列中，通过最大化序列的可能性并精确校正错过的事件。采用了具有两个不同结合位点的机制。适用于勤奋受体的速率常数（打开，关闭和总解离速率）被稳健地估计，对拟合过程中所做的确切假设不敏感，正如模拟研究所期望的那样。它们足以预测受体的主要生理特性。突变后的εL221F使受体的解离速率降低了约4倍，而打开速率和平均打开时间的增加幅度较小。这些足以解释在患者中观察到的微型突触电流衰减速度约为原来的6倍。两个结合位点之间的区别不太明显，速率常数的估计在某种程度上依赖于假设，例如是否包括额外的短期关闭状态，或者EC50是否受到约束。结果表明，在野生型中，这两个结合位点对乙酰胆碱关闭受体的亲和力相差约10倍，而在εL221F突变中，较低的亲和力增加，因此两个位点变得更相似。
The mechanisms that underlie activation of nicotinic receptors are investigated using human recombinant receptors, both wild type and receptors that contain the slow channel myasthenic syndrome mutation, εL221F. The method uses the program HJCFIT, which fits the rate constants in a specified mechanism directly to a sequence of observed open and shut times by maximising the likelihood of the sequence with exact correction for missed events. A mechanism with two different binding sites was used. The rate constants that apply to the diliganded receptor (opening, shutting and total dissociation rates) were estimated robustly, being insensitive to the exact assumptions made during fitting, as expected from simulation studies. They are sufficient to predict the main physiological properties of the receptors. The εL221F mutation causes an approximately 4‐fold reduction in dissociation rate from diliganded receptors, and a smaller increase in opening rate and mean open time. These are sufficient to explain the approximately 6‐fold slowing of decay of miniature synaptic currents seen in patients. The distinction between the two binding sites was less robust, the estimates of rate constants being dependent to some extent on assumptions, e.g. whether an extra short‐lived shut state was included or whether the EC50 was constrained. The results suggest that the two binding sites differ by roughly 10‐fold in the affinity of the shut receptor for ACh in the wild type, and that in the εL221F mutation the lower affinity is increased so the sites become more similar.
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基于序列同一性和残基位置的烟碱受体胞外结构域模型。
DOI：
10.1016/s0006-3495(97)78047-0
发表时间：
1997
期刊：
Biophysical journal.
影响因子：
--
作者：
Tsigelny,I;Sugiyama,N;Sine,SM;Taylor,P
通讯作者：
Taylor,P
影响因子：
3.4
作者：
HORN, R;LANGE, K
通讯作者：
LANGE, K
影响烟碱乙酰胆碱受体激动剂敏感性的突变。
影响因子：
3.4
作者：
Tomaselli,GF;McLaughlin,JT;Jurman,ME;Hawrot,E;Yellen,G
通讯作者：
Yellen,G
烟碱乙酰胆碱受体的α亚基中的保守酪氨酸稳定激动剂和箭毒拮抗剂的季铵基团。
DOI：
--
发表时间：
1994
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Sine,SM;Quiram,P;Papanikolaou,F;Kreienkamp,HJ;Taylor,P
通讯作者：
Taylor,P
鱼雷乙酰胆碱受体配体诱导激活的突变分析。
DOI：
--
发表时间：
1992
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
O'Leary,ME;White,MM
通讯作者：
White,MM