Two adjacent phenylalanines in the NMDA receptor GluN2A subunit M3 domain interactively regulate alcohol sensitivity and ion channel gating.
Two adjacent phenylalanines in the NMDA receptor GluN2A subunit M3 domain interactively regulate alcohol sensitivity and ion channel gating.
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NMDA 受体 GluN2A 亚基 M3 结构域中的两个相邻苯丙氨酸交互调节酒精敏感性和离子通道门控。
DOI：
10.1016/j.neuropharm.2016.11.013
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发表时间：
2017
影响因子：
4.7
通讯作者：
Peoples,RobertW
中科院分区：
文献类型：
--
作者：
Ren,Hong;Zhao,Yulin;Wu,Man;Dwyer,DonardS;Peoples,RobertW
然后-甲基-d-天冬氨酸(NMDA)受体是中枢神经系统中乙醇作用的关键靶点。酒精对NMDA受体功能的抑制涉及到第三和第四膜相关(M)结构域上的小簇残基。本实验室先前的研究结果表明，M3结构域的两个相邻位置，F636和F637，可以有效地调节酒精敏感性和离子通道门控。在这项研究中，我们报告了这些位置在NMDA受体门控和酒精作用的调节中相互作用。利用双突变循环分析，我们检测了这些位置上不同替换突变体之间的相互作用，涉及调节谷氨酸EC50、稳态与峰值电流比(ISS：IP)、平均打开时间和乙醇IC50。这种相互作用显然涉及M3螺旋上的力的平衡，因此一个位置的替换引起的功能中断可以被另一个位置的类似替换所逆转。例如，F636或F637的色氨酸替换分别增加或减少了通道平均开放时间，但这两个位置的色氨酸替换并不改变开放时间。有趣的是，许多突变对受体动力学和乙醇敏感性的影响似乎依赖于细微的结构差异，例如异构体氨基酸亮氨酸和异亮氨酸之间的差异，因为它们不能基于侧链分子体积或亲水性来解释。
TheN-methyl-d-aspartate (NMDA) receptor is a key target of ethanol action in the central nervous system. Alcohol inhibition of NMDA receptor function involves small clusters of residues in the third and fourth membrane-associated (M) domains. Previous results from this laboratory have shown that two adjacent positions in the M3 domain, F636 and F637, can powerfully regulate alcohol sensitivity and ion channel gating. In this study, we report that these positions interact with one another in the regulation of both NMDA receptor gating and alcohol action. Using dual mutant cycle analysis, we detected interactions among various substitution mutants at these positions with respect to regulation of glutamate EC50, steady-state to peak current ratios (Iss:Ip), mean open time, and ethanol IC50. This interaction apparently involves a balancing of forces on the M3 helix, such that the disruption of function due to a substitution at one position can be reversed by a similar substitution at the other position. For example, tryptophan substitution at F636 or F637 increased or decreased channel mean open time, respectively, but tryptophan substitution at both positions did not alter open time. Interestingly, the effects of a number of mutations on receptor kinetics and ethanol sensitivity appeared to depend upon subtle structural differences, such as those between the isomeric amino acids leucine and isoleucine, as they could not be explained on the basis of sidechain molecular volume or hydrophilicity.