THREE DIMENSIONAL MODELS FOR MEMBRANE RECEPTOR PROTEINS

整合膜受体蛋白通常在信号转导中起关键作用。 细菌和高等生物体中跨细胞膜的转导。 对这些受体的三维结构的详细了解 蛋白质无疑将极大地有助于对 信号转导的分子机制，但令人敬畏 技术挑战阻碍了高分辨率的常规测定 目前大多数膜蛋白的结构。因此，计算机 建议进行建模研究以生成详细的三维 细菌膜化学受体Trg受体的模型 大肠杆菌与哺乳动物多个七螺旋G蛋白偶联 受体，肾上腺素能神经递质受体。几个具体的 将讨论肾上腺素能受体结构/功能的问题 主要利用交互式分子图形建模 技术和现有的实验数据，包括：(1)什么详细 肾上腺素能受体中7个螺旋束的堆积排列 与可用的配基结合和结构信息最一致 对于这些受体，同时也产生了敏感的物理化学性质 简介？(2)单一的、通用的三维肾上腺素能受体 满足上述问题1的条件的模型解释 不同配体结合选择性的重叠和差异 受体亚型？在此项目中生成的模型将用于 设计亲和标记配体，与Peter Jeffs博士合作，位于 葛兰素史克，它将共价结合α和β肾上腺素能受体。 这些共价加合物将用质谱学进行表征 提供有关结构和组成的新信息的技术 配基结合部位的位置。最后，一个精致的三维模型 对于β2肾上腺素能受体将被用来筛选Fine 新的(即非肾上腺素能)化合物的化学品数据库 具有合理的约束亲和力。三维数据库检索 将采用各种方法，并将测试有希望的目标化合物 与Raymond教授合作的Beta2受体配体结合分析 加州大学伯克利分校的史蒂文斯。第二组建模研究将是 与华盛顿的杰拉尔德·哈泽尔鲍尔教授合作进行 州立大学生成详细的三维模型 细菌Trg化学受体。利用来自巯基的数据 可及性、交联性和自旋标记研究由教授进行。 哈泽尔鲍尔的研究小组对52个Trg受体的单半胱氨酸突变进行了研究， 受体跨膜区和周质区的结构 将被构建，并与构象变化相关的模型 关于信号转导的研究将会被探索。模型结构将是 探索过了。模型结构将不断进行评估和改进 使用了来自哈泽尔鲍尔教授实验室的新实验数据。这个 结合详细的模型构建和与 实验小组应该提供关于结构的有用的新信息 以及两种不同类型的膜的信号转导机制 受体蛋白。为肾上腺素能受体获得的信息可能 也可用于设计针对这些药物的药物 感受器。

Integral membrane receptor proteins often play a key role in signal transduction across cell membranes in both bacteria and higher organisms. Detailed knowledge of the three-dimensional structures of these receptor proteins would undoubtedly contribute greatly to a general understanding of the molecular mechanisms of signal transduction, but formidable technical challenges prohibit the routine determination of high resolution structures for most membrane proteins at present. Therefore, computer modeling studies are proposed to generate detailed three-dimensional models for a bacterial membrane chemoreceptor, the Trg receptor from Escherichia coli, and a number of mammalian seven helix G protein-coupled receptors, the adrenergic neurotransmitter receptors. Several specific issues of adrenergic receptor structure/function will be addressed utilizing primarily interactive molecular graphics model building techniques and existing experimental data, including: (1) What detailed packing arrangement of the seven helix bundles in adrenergic receptors is most consistent with available ligand binding and structural information for these receptors, while also yielding sensible physicochemical property profiles? (2) Can a single, general three-dimensional adrenergic receptor model that fulfills the conditions imposed on question 1 above explain the overlap, and differences, of ligand binding selectivities for various receptor subtypes? The models generated in this project will be used to design affinity labeling ligands, in collaboration with Dr. Peter Jeffs at Glaxo, that will covalently bind alpha- and beta-adrenergic receptors. These covalent adducts will be characterized using mass spectrometric techniques to provide new information about the structure and composition of the ligand binding site. Finally, a refined three-dimensional model for the beta2 adrenergic receptor will be used to screen the Fine Chemicals data base for novel (i.e. non-adrenergic) compounds that may possess reasonable binding affinities. Three-dimensional data base search methods will be employed, and promising target compounds will be tested in a beta2 receptor ligand binding assay in collaboration with Prof. Raymond Stevens at UC-Berkeley. A second set of modeling studies will be undertaken in collaboration with Prof. Gerald Hazelbauer at Washington State University to generate detailed three-dimensional models for the bacterial Trg chemoreceptor. Utilizing data from sulfhydryl accessibility, crosslinking, and spin labeling studies performed by Prof. Hazelbauer's group for 52 single cysteine mutants of the Trg receptor, structures for the transmembrane and periplasmic domains of the receptor will be constructed, and models for the conformational changes associated with signal transduction will be explored. The model structures will be explored. The model structures will be continually evaluated and refined using new experimental data from Prof. Hazelbauer's laboratory. The combination of detailed model building and close collaboration with experimental groups should yield useful new information about structure and signal transduction mechanisms for two distinct classes of membrane receptor proteins. Information obtained for the adrenergic receptors may also be of use in design of pharmacologic agents targeted to these receptors.