Serotonin Transporter Intracellular Structure Function Relationships

5-羟色胺转运体（SERT）在脑内5-羟色胺的作用和循环中起着重要作用。SERT是一种质膜蛋白，其在突触附近的细胞外空间中结合5-羟色胺，将其转运穿过膜，并将其释放到细胞质中。它是摇头丸（3.4-亚甲二氧基甲基苯丙胺，MDMA）和可卡因等滥用药物以及百忧解和丙咪嗪等抗抑郁药等治疗药物的目标。它与其他神经递质转运蛋白如多巴胺、去甲肾上腺素、GABA和甘氨酸的转运蛋白密切相关。作为对SERT的结构和功能的更广泛兴趣的一部分，很明显，面向细胞质的转运蛋白部分 在运输过程中发生重要的构象变化。该胞内结构域由蛋白质的NH 2-和COOH-末端和五个胞内环组成。目前的建议旨在了解这些细胞内元件的结构和功能，在三个具体的目标。其中第一个是通过半胱氨酸诱变扫描细胞内环，以确定环和跨膜结构域之间的边界。第二个目的是研究细胞内环之间特异性相互作用形成转运蛋白细胞内结构的可能性。第三个目的是检验5-羟色胺转运途径部分由环和跨膜结构域形成的假设。预计这些实验的结果将阐明相关多巴胺和去甲肾上腺素转运蛋白以及神经递质转运蛋白家族其他成员的结构和功能。

Serotonin transporter (SERT) plays an important role in the action and recycling of serotonin in the brain. SERT is a plasma membrane protein that binds serotonin in the extracellular space near a synapse, transports it across the membrane, and releases it to the cytoplasm. It is the target for drugs of abuse such as ecstasy (3.4-methylenedioxymethamphetamine, MDMA) and cocaine, as well as therapeutic drugs such as antidepressants like Prozac and imipramine. It is closely related to other neurotransmitter transporters such as those for dopamine, norepinephrine, GABA and glycine. As part of a wider interest in the structure and function of SERT, it has become apparent that the part of the transporter that faces the cytoplasm undergoes important conformational changes during transport. This intracellular domain consists of the NH2- and COOH-termini of the protein and five intracelluar loops. The current proposal seeks to understand the structure and function of these intracellular elements in three specific aims. The first of these is to scan the intracellular loops by cysteine mutagenesis to determine the boundaries between the loop and transmembrane domains. The second aim is to examine the possibility that intracellular loops interact specifically with each other to form the intracellular structure of the transporter. The third aim is to test the hypothesis that the translocation pathway for serotonin is formed, in part, by loops as well as transmembrane domains. It is expected that the results of these experiments will shed light on the structure and function of the related dopamine and norepinephrine transporters as well as of other members of the neurotransmitter transporter family.