MOLECULAR FUNCTION OF RECEPTORS AND TRANSPORTERS AT CHEMICAL SYNAPSES

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 该项目涉及三种不同和独特的完整膜蛋白：(1)细菌运输蛋白(‘X4’)；(2)真核细胞的P2X离子通道；(3)真核的全长离子型谷氨酸受体(IGluR)。对于所有三个项目，测量尽可能高分辨率的衍射数据集的科学或技术目的是相同的。这是一个巨大的挑战，因为所有这些晶体的衍射性都很弱，它们都是完整的膜蛋白晶体，而且很大一部分晶体体积由水溶液和无序的洗涤剂和脂质分子组成。特别是，对于X4项目，我们的目标是收集NE-CAT微焦光束线上的高分辨率原始数据和ID-24光束线上的多波长数据。对于P2X项目，由于我们有低分辨率的相位，我们正在测量微聚焦光束线上的本地数据集(使用和不使用激动剂和调制器)。在谷氨酸受体项目中，我们使用分子置换中细胞外域的已知结构来获得相信息，因此重点是测量大量激动剂、拮抗剂和变构调节剂复合体的单波长数据。 这三个项目的重要性都很大。据我所知，X4和P2X蛋白的折叠目前尚不清楚，即所确定的折叠可能是唯一的，因此这些初始结构将为两大类非常重要的膜蛋白提供结构蓝图。此外，详细的结构分析还将提供对分子机制的深入和迄今未知的见解。在谷氨酸受体的情况下，完整受体的结构将为深入了解离子通道门控及其调节机制，以及离子渗透和阻断提供深刻的见解。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This project involves three different and unique integral membrane proteins: (1) a bacterial transport protein ('X4'); (2) a eukaryotic P2X ion channel; and (3) a eukaryotic, full-length ionotropic glutamate receptor (iGluR). For all three projects, the scientific or technical purpose is the same  to measure the highest resolution diffraction data sets possible. This presents a great challenge because all these crystals diffract weakly  they are crystals of integral membrane proteins and a large fraction of the crystal volume is composed of aqueous solution and disordered detergent and lipid molecules. In particular, for the X4 project, we are aiming to collect high resolution native data on the NE-CAT microfocus beam line and multiwavelength data on the ID-24 beam line. For the P2X project, since we have low resolution phases, we are measuring native data sets (with and without agonists and modulators) on the microfocus beam line. In the case of the glutamate receptor project, we are using the known structures of the extracellular domains in molecular replacement to obtain phase information, and thus the emphasis is on measuring single wavelength data on a large number of agonist, antagonist and allosteric modulator complexes. The importance of all three projects is substantial. To the best of my knowledge, the folds for the X4 and P2X proteins are currently unknown, i.e. the determined folds are likely to be unique, and thus these initial structures will provide the architectural blueprint for two large and very important classes of membrane proteins. The detailed structural analysis, in addition, will provide deep and as-of-yet unknown insights into molecular mechanism. In the case of the glutamate receptor, the structure of the intact receptor will provide profound insights into the mechanism of ion channel gating and its modulation, as well as into ion permeation and block.