LIGAND & SUBUNIT INTERACTIONS OF TRANSMEMBRANE RECEPTORS

描述：研究提出的天冬氨酸和丝氨酸受体 来自大肠杆菌趋化性途径的蛋白质，以及 与它们相互作用的细胞质信号蛋白， 连锁，协同性，构象变化和聚类， 定量热力学（等温滴定量热法）和 光谱方法（荧光和EPR）与生化测定 信号活动。 许多跨膜受体的特征是二聚体，或更一般地， 低聚物，结合的组织允许系统表现出 合作性和联系现象，这些现象对 许多膜现象。 在生理条件下， 了解跨膜信号传导发生的程度， 通过稳定簇内的构象变化实现受体聚集 受体，或两者。 这些问题可以得到解决，如果更多的信息 关于构象变化，聚集反应， 以及配体结合在膜的相对侧上的相互影响， 膜（transbilayer binding effects）。 拟将这一 信息将通过（一）精确测量 表征配体结合的热力学和动力学参数， 膜蛋白的结构域相互作用和亚基相互作用，（ii） 准确和灵敏的光谱方法，以确定 受体构象和动力学响应配体结合， 蛋白质-蛋白质相互作用，和（iii）定位的网站， 信号蛋白之间的相互作用。 完成拟议的研究后， 跨膜信号转导的物理机制和分子机制 通过共价修饰使受体脱敏。 细菌 趋化性通路属于双组分信号转导超家族 在原核生物、真核微生物和 植物 因此，这些信息应该具有广泛的基础性 重要性，也与理解信号直接相关 病原微生物的转导过程。

DESCRIPTION: Studies are proposed of the aspartate and serine receptor proteins from the Escherichia coli chemotaxis pathway, and of the cytoplasmic signalling proteins with which they interact, regarding issues of linkage, cooperativity, conformational change and clustering using quantitative thermodynamic (isothermal titration calorimetry) and spectroscopic methods (Fluorescence and EPR) with biochemical assays of signalling activity. A feature of many transmembrane receptors is the dimeric, or more generally oligomeric, organization of binding permits the system to exhibit cooperativity and linkage phenomena that have important consequences for many membrane phenomena. Under physiological conditions it is not understood the extent to which transmembrane signalling occurs by changes in receptor clustering, through conformational changes within stable clusters of receptor, or both. These issues could be resolved if more information were available about the conformational changes, the clustering reactions, and the mutual influence of ligands binding on opposite sides of the membrane (transbilayer binding effects). It is proposed that this information will be obtained through (i) precise measurements of the thermodynamic and kinetic parameters that characterize ligand binding, domain interaction and subunit interaction of membrane proteins, (ii) accurate and sensitive spectroscopic methods to determine changes in receptor conformation and dynamics in response to ligand binding and protein-protein interactions, and (iii) localization of the sites of interaction between signalling proteins. Completion of the proposed studies will give a complete picture of the physical mechanism of transmembrane signalling and the molecular mechanism of receptor desensitization by covalent modification. The bacterial chemotaxis pathway belongs to the superfamily of two-component signalling systems that have been found in prokaryotes, eukaryotic microorganisms and plants. The information should thus be of widespread fundamental significance, and also directly relevant to understanding signal transduction processes in pathogenic microbes.