Interactions of tryptamine derivatives with serotonin transporter species variants implicate transmembrane domain I in substrate recognition
Interactions of tryptamine derivatives with serotonin transporter species variants implicate transmembrane domain I in substrate recognition
复制标题
色胺衍生物与血清素转运蛋白物种变体的相互作用表明跨膜结构域 I 参与底物识别
DOI：
10.1124/mol.59.3.514
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发表时间：
2001-03-01
影响因子：
3.6
通讯作者：
Blakely, RD
中科院分区：
文献类型：
--
作者：
Adkins, EM;Barker, EL;Blakely, RD
血清素（5-羟色胺，5-HT）转运体（SERT）负责突触5-HT的失活，也是多种精神兴奋剂的靶点。尽管SERT在5-HT失活和精神兴奋反应中起着关键作用，但转运蛋白对配体的识别的许多方面都不清楚。我们利用SERT物种变体的序列差异来鉴定底物识别的结构决定因素。在苯环上的4和7位、吲哚氮和β位上具有取代的色胺衍生物在用人或果蝇SERT cDNA转染的细胞中抑制[（3）H]5-HT转运的效力差异高达40倍。这些衍生物的物种选择性在很大程度上体现在拮抗剂结合中。人类/D.黑腹鼠SERT嵌合体研究表明，前两个SERT跨膜结构域（TMD）与吲哚氮取代化合物N-异丙基色胺（NIT）、5-甲氧基-N-异丙基色胺（5-MNIT）和7-取代化合物7-苄氧基色胺（7 BT）的效力有关。在4位和β位具有取代的类似物的效力差异受到该区域远端序列的影响。在TMD I-II中，物种扫描诱变涉及单个残基（人SERT中的Y 95，D.在NIT、5-MNIT和7 BT的识别中，值得注意的是，这是相同的网站，我们以前建立的物种特异性识别的拮抗剂西酞普兰和马吲哚。这些研究结果支持TMD I残基在定义SERT底物和拮抗剂识别的共享方面中的关键作用。
The serotonin (5-hydroxytryptamine, 5-HT) transporter (SERT) is responsible for the inactivation of synaptic 5-HT and is also a target for multiple psychostimulants. Despite the critical role of SERT in 5-HT inactivation and psychostimulant response, many aspects of the transporter's recognition of ligands are poorly defined. We took advantage of sequence divergence of SERT species variants to identify structural determinants of substrate recognition. Tryptamine derivatives with substitutions at the 4 and 7 positions on the phenyl ring, the indole nitrogen, and the beta position show up to 40-fold potency differences for inhibiting [(3)H]5-HT transport in cells transfected with either human or Drosophila melanogaster SERT cDNAs. Species selectivities of these derivatives were largely recapitulated in antagonist binding. Human/D. melanogaster SERT chimera studies implicated the first two SERT transmembrane domains (TMDs) in the potency of the indole nitrogen-substituted compounds N-isopropyltryptamine (NIT), 5-methoxy-N-isopropyltryptamine (5-MNIT), and the 7-substituted compound 7-benzyloxytryptamine (7BT). Potency differences of analogs with substitutions at the 4 and beta positions are influenced by sequences distal to this region. Within TMD I-II, species-scanning mutagenesis implicated a single residue (Y95 in human SERT, F90 in D. melanogaster SERT) in the recognition of NIT, 5-MNIT, and 7BT. Remarkably, this is the same site we established previously in species-specific recognition of the antagonists citalopram and mazindol. These findings support a critical role for TMD I residues in defining shared aspects of SERT substrate and antagonist recognition.