Structure and Function of Neurotransmitter Transporters

神经元之间的信号传递在很大程度上是通过化学神经传递完成的， 从突触前神经元释放神经递质，检测受体上的递质 位于突触后和突触前神经元，神经递质对递质的“摄取” 钠同向转运体（NSS）。NSSs是钠偶联膜转运蛋白，其利用前- 现有的离子梯度将神经递质“泵”入细胞，提高浓度梯度。因为 从突触间隙和周围的细胞外空间中去除递质对于 神经传递，NSS的功能障碍是许多神经系统疾病的基础， 重要的治疗剂，以及非法物质，目标是NSS，包括抗抑郁药，抗抑郁药， 焦虑药物安非他明和可卡因本文所述的研究目标 申请资助是为了进一步了解NSS功能的生化机制，更好地 了解小分子治疗剂和非法物质如何与NSS相互作用，并提供 对NSS中选定的天然突变的后果的基于结构的理解 基因.研究的主要重点将是研究人类血清素和多巴胺转运蛋白 使用单粒子低温电子显微镜（cryo-EM）和X射线晶体学的结构方法 结合互补的生物化学、生物物理学和计算方法。我们 特别感兴趣的理解，在分子细节的水平上，NSSs如何从 将神经递质结合到向内构象所需的向外构象， 需要释放变送器。此外，我们将阐明分子接触的基础， 关键小分子和NSS之间的相互作用，以了解亲和性和特异性的原理， 我们还将研究关键的翻译后修饰，如磷酸化， 转运蛋白构象我们的研究结果将使我们能够全面了解 国家安全系统结构和功能之间的关系，它们也将为进一步 具有潜在有用性质的小分子的基于结构的设计。我们的研究不仅会告诉 直接的NSS领域，但因为NSS是范式整合膜转运蛋白，我们的 这些研究将启发更大的膜转运领域。

Signaling between neurons is accomplished, in large part, by chemical neurotransmission which involves the release of neurotransmitter from a presynaptic neuron, the detection of the transmitter on receptors located on both post- and presynaptic neurons, and the `uptake' of the transmitter by neurotransmitter sodium symporters (NSSs). NSSs are sodium-coupled membrane transport proteins that harness the pre- existing ion gradient to `pump' neurotransmitters into cells, up the concentration gradient. Because the removal of transmitter from the synaptic cleft and surrounding extracellular spaces is crucial to neurotransmission, dysfunction of NSSs underpins a number of neurological conditions and there are many important therapeutic agents, as well as illicit substances, that target NSSs, including antidepressants, anti- anxiety medications, amphetamines and cocaine, as examples. The goals of the research described in this grant application are to further our understanding of the biochemical mechanism of NSS function, to better understand how small molecule therapeutic agents and illicit substances interact with NSSs and to provide structure-based understanding of the consequences of selected naturally occurring mutations in NSS genes. The major focus of the research will be to study the human serotonin and dopamine transporters using the structural methods of single particle cryo electron microscopy (cryo-EM) and x-ray crystallography in combination with complementary biochemical, biophysical and computational methods. We are particularly interested in understanding, at the level of molecular detail, how NSSs isomerize from the outward facing conformations required to bind neurotransmitter to the inward facing conformations that are required to release transmitter. Moreover, we will elucidate the molecular contacts that underpin the interactions between key small molecules and NSSs to understand the principles of affinity and specificity, and we will also examine how key posttranslational modifications, such as phosphorylation, affect transporter conformation. The results from our studies will allow for a comprehensive understanding of the relationships between NSS structure and function and they will also provide an underpinning for further structure-based design of small molecules with potentially useful properties. Our studies will not only inform the immediate NSS field but, because NSSs are paradigm integral membrane transporter proteins, our studies will enlighten the much larger field of membrane transport.