Mutations of L293 in transmembrane two of the mouse 5-hydroxytryptamine3A receptor alter gating and alcohol modulatory actions.
Mutations of L293 in transmembrane two of the mouse 5-hydroxytryptamine3A receptor alter gating and alcohol modulatory actions.
复制标题
小鼠 5-羟色胺 3A 受体跨膜区 L293 的突变改变了门控和酒精调节作用。
DOI：
10.1038/sj.bjp.0706685
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发表时间：
2006
影响因子：
7.3
通讯作者：
Machu,TinaK
中科院分区：
文献类型：
--
作者：
Hu,Xiang-Qun;Hayrapetyan,Volodya;Gadhiya,JayJ;Rhubottom,HeatherE;Lovinger,DavidM;Machu,TinaK
本研究的目的是确定5-HT 3A受体中TM 2 15′位L293突变是否改变宏观电流动力学，以及这些变化是否可以解释酒精调节的改变。在电压钳和HEK 293细胞与全细胞膜片钳记录和快速药物应用下，非洲爪蟾卵母细胞受体功能进行了评估。L293 C和L293 S受体对单独激动剂的反应的检查显示相对于野生型受体增强的激活、失活和脱敏速率。L293 G突变使失活和脱敏速率显著减慢。在这些突变体受体中也观察到5-HT的效力增加和部分激动剂DA的效力增加。在含有L293突变为C、G或S的受体中，乙醇和三氯乙醇（TCEt）对受体功能的增强作用降低或消除。L293 I突变受体保留乙醇和TCEt敏感性。乙醇和TCEt增强了野生型受体的激活率，但对L293 G和L293 S受体没有影响。未观察到取代氨基酸的任何理化性质与酒精增强功能的变化之间的关系。突变受体中受体通道特性的变化支持了L293残基在通道门控中具有重要作用的观点。我们的研究结果表明，损失的变构调节醇是不相关的，在任何简单的方式来改变通道动力学特性所带来的L293突变体。我们没有观察到任何证据表明L293是酒精结合位点的一部分。
The goal of this study was to determine whether mutations of L293 at the 15′ position of TM2 in the 5-HT3A receptor alter macroscopic current kinetics, and if these changes could account for alterations in alcohol modulation. Receptor function was assessed in Xenopus oocytes under voltage-clamp and in HEK293 cells with whole-cell patch-clamp recording and rapid drug application. Examination of responses of L293C and L293S receptors to agonist alone revealed enhanced activation, deactivation, and desensitization rates relative to the wild-type receptor. The L293G mutation produced marked slowing of deactivation and desensitization rates. Increased potency of 5-HT and increased efficacy of the partial agonist, DA, was also observed in these mutant receptors. Ethanol and trichloroethanol (TCEt) enhancement of receptor function was reduced or eliminated in receptors containing L293 mutations to C, G, or S. The L293I mutant receptor retained ethanol and TCEt sensitivity. Ethanol and TCEt enhanced activation rate in the wild-type, but not the L293G and L293S receptors. No relationship was observed between any physicochemical property of the substituted amino acids and the change in alcohol potentiation of function. The changes in receptor-channel properties in the mutant receptors support the idea that the L293 residue has important roles in channel gating. Our findings indicate that loss of allosteric modulation by alcohols is not related in any simple way to changes in channel kinetic properties brought about by L293 mutants. We did not observe any evidence that L293 is part of an alcohol binding site.