Characterization of an allosteric citalopram-binding site at the serotonin transporter
Characterization of an allosteric citalopram-binding site at the serotonin transporter
复制标题
DOI：
10.1111/j.1471-4159.2004.02835.x
复制
发表时间：
2005-01-01
影响因子：
4.7
通讯作者：
Wiborg, O
中科院分区：
文献类型：
--
作者：
Chen, FH;Larsen, MB;Wiborg, O
5-羟色胺转运蛋白（serotonin transporter，SERT）是钠/氯依赖性转运蛋白家族的一员，是治疗抑郁症和焦虑症等多种临床疾病的主要药理学靶点。在本研究中，我们表明，[H-3] S-西酞普兰从人SERT的解离速率，是由血清素的存在下，以及由几种抗抑郁药，当存在于解离缓冲液延迟。S-西酞普兰对[H-3] S-西酞普兰从SERT中解离的抑制作用最强，其次是R-西酞普兰、舍曲林、5-羟色胺和帕罗西汀。S-和R-西酞普兰的EC 50值分别为3.6 +/- 0.4 μ M和19.4 +/- 2.3 μ M。氟西汀、文拉法辛和度洛西汀对[H-3] S-西酞普兰的解离无明显影响。解离的别构调节与温度或解离缓冲液中Na+的存在无关。[H-3] S-西酞普兰与SERT双突变体N208 Q/N217 Q的复合物的解离被延迟到与野生型相似的程度，这表明它不能自组装成寡聚复合物，从而提高了变构机制在单个亚基内介导的可能性。一项比较人和牛SERT的物种扫描诱变研究显示，Met 180，Tyr 495和Ser 513是介导变构效应的重要残基，并有助于在主要位点的高亲和力结合。
The serotonin transporter (SERT), which belongs to a family of sodium/chloride-dependent transporters, is the major pharmacological target in the treatment of several clinical disorders, including depression and anxiety. In the present study we show that the dissociation rate, of [H-3]S-citalopram from human SERT, is retarded by the presence of serotonin, as well as by several antidepressants, when present in the dissociation buffer. Dissociation of [H-3]S-citalopram from SERT is most potently inhibited by S-citalopram followed by R-citalopram, sertraline, serotonin and paroxetine. EC50 values for S- and R-citalopram are 3.6 +/- 0.4 muM and 19.4 +/- 2.3 muM, respectively. Fluoxetine, venlafaxine and duloxetine have no significant effect on the dissociation of [H-3]S-citalopram. Allosteric modulation of dissociation is independent of temperature, or the presence of Na+ in the dissociation buffer. Dissociation of [H-3]S-citalopram from a complex with the SERT double-mutant, N208Q/N217Q, which has been suggested to be unable to self-assemble into oligomeric complexes, is retarded to an extent similar to that found with the wild-type, raising the possibility that the allosteric mechanism is mediated within a single subunit. A species-scanning mutagenesis study comparing human and bovine SERT revealed that Met180, Tyr495 and Ser513 are important residues in mediating the allosteric effect, as well as contributing to high-affinity binding at the primary site.