Evidence that ethanol acts on a target in Loop 2 of the extracellular domain of α1 glycine receptors
Evidence that ethanol acts on a target in Loop 2 of the extracellular domain of α1 glycine receptors
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DOI：
10.1111/j.1471-4159.2007.04680.x
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发表时间：
2007-09-01
影响因子：
4.7
通讯作者：
Alkana, Ronald L.
中科院分区：
文献类型：
--
作者：
Crawford, Daniel K.;Trudell, James R.;Alkana, Ronald L.
大量证据表明乙醇作用于甘氨酸受体跨膜结构域中的特定残基。在这项研究中，我们测试的假设，细胞外结构域也是一个目标乙醇的行动调查的影响，半胱氨酸取代位置52（细胞外结构域）和267（跨膜结构域）对正醇和丙甲硫基磺酸盐（PMTS）在α 1GlyRs在非洲爪蟾卵母细胞中表达的反应。为了支持这一假设：（i）与WT GlyR相比，A52 C突变改变了乙醇敏感性;（ii）PMTS在A52 C GlyR中产生了不可逆的酒精样增强作用;（iii）PMTS结合降低了A52 C GlyR中的正链酒精截止值。进一步的研究使用与位置52或267处的半胱氨酸结合的PMT来阻断一个位点处的乙醇作用，以确定其在其他位点处的作用。在这些情况下，乙醇在作用于位置52时引起负调制，在作用于位置267时引起正调制。总的来说，这些发现与将TM结构域确定为乙醇靶点的证据相一致，表明位置52和267是相同醇口袋的一部分，并表明乙醇对GlyR功能的净效应反映了其对不同靶点的正调节作用和负调节作用的总和。
Considerable evidence indicates that ethanol acts on specific residues in the transmembrane domains of glycine receptors (GlyRs). In this study, we tested the hypothesis that the extracellular domain is also a target for ethanol action by investigating the effect of cysteine substitutions at positions 52 (extracellular domain) and 267 (transmembrane domain) on responses to n-alcohols and propyl methanethiosulfonate (PMTS) in alpha 1GlyRs expressed in Xenopus oocytes. In support of the hypothesis: (i) The A52C mutation changed ethanol sensitivity compared to WT GlyRs; (ii) PMTS produced irreversible alcohol-like potentiation in A52C GlyRs; and (iii) PMTS binding reduced the n-chain alcohol cutoff in A52C GlyRs. Further studies used PMTS binding to cysteines at positions 52 or 267 to block ethanol action at one site in order to determine its effect at other site(s). In these situations, ethanol caused negative modulation when acting at position 52 and positive modulation when acting at position 267. Collectively, these findings parallel the evidence that established the TM domain as a target for ethanol, suggest that positions 52 and 267 are part of the same alcohol pocket and indicate that the net effect of ethanol on GlyR function reflects the summation of its positive and negative modulatory effects on different targets.