Department of Cell Physiology and Molecular Biophysics and Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX.
Department of Cell Physiology and Molecular Biophysics and Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX
J Gen Physiol. 2019 Sep 2;151(9):1135-1145. doi: 10.1085/jgp.201912421. Epub 2019 Aug 13.
Serotonin type 3 receptors (5-HTRs) are cation-conducting pentameric ligand-gated ion channels and members of the Cys-loop superfamily in eukaryotes. 5-HTRs are found in the peripheral and central nervous system, and they are targets for drugs used to treat anxiety, drug dependence, and schizophrenia, as well as chemotherapy-induced and postoperative nausea and emesis. Decades of research of Cys-loop receptors have identified motifs in both the extracellular and transmembrane domains that mediate pentameric assembly. Those efforts have largely ignored the most diverse domain of these channels, the intracellular domain (ICD). Here we identify molecular determinants within the ICD of serotonin type 3A (5-HT) subunits for pentameric assembly by first identifying the segments contributing to pentamerization using deletion constructs of, and finally by making defined amino acid substitutions within, an isolated soluble ICD. Our work provides direct experimental evidence for the contribution of three intracellular arginines, previously implicated in governing the low conductance of 5-HTRs, in structural features such as pentameric assembly.
5-羟色胺能 3 型受体（5-HTRs）是阳离子传导的五聚体配体门控离子通道，也是真核生物 C 型环超级家族的成员。5-HTRs 存在于外周和中枢神经系统中，是用于治疗焦虑、药物依赖和精神分裂症以及化疗诱导和术后恶心和呕吐的药物的靶点。C 型环受体的数十年研究已经确定了在细胞外和跨膜结构域中调节五聚体组装的基序。这些努力在很大程度上忽略了这些通道最多样化的结构域，即细胞内结构域（ICD）。在这里，我们通过首先使用缺失构建体来识别参与五聚体化的片段，最后通过在分离的可溶性 ICD 内进行明确的氨基酸取代，来确定 5-羟色胺能 3A（5-HT）亚基 ICD 内的分子决定因素，用于五聚体组装。我们的工作为三个细胞内精氨酸（先前涉及调节 5-HTRs 的低电导）在结构特征（如五聚体组装）中的贡献提供了直接的实验证据。
