STRUCTURE AND FUNCTION OF BACTERIORHODOPSIN

细菌视紫红质是一种27000道尔顿的膜蛋白 盐生盐杆菌紫色膜的定义是高 膜的分辨电子衍射和膜的重电子衍射 共价连接的金属基团。在我们以前研究的基础上，我们可以 现在按顺序确定这些标签的粘贴位置和 结构。因此，主要目标是确定顺序和 七个跨膜序列在细胞内的取向 结构。我们以前已经确定了电子的相 实验上(即，从图像)到3.7埃的衍射幅度， 在-120摄氏度下记录了2.65埃的衍射，这对 差值映射。我们定义了一个7x10埃的扩展分辨率 显示有助于构建模型的附加功能的3-D结构 蛋白质结构：在定义了视网膜附着位置后 序列，我们将确定参与质子机制的侧链 使用定点突变的蛋白泵送，并使用 在加州大学旧金山分校的H.Boyer提出的一个密切互补的建议中进行研究。这个 场地的具体变化将基于结构，并且既有结构性的 将评估变化和功能差异，以确定 光能转换、插入膜、膜蛋白 稳定性，脯氨酸的作用，螺旋之间的多肽在 水相，最终目的是了解 跨膜蛋白介导现象的原型。渐增 与眼睛中的视紫红质的相似之处正在显现。总体目标是 了解膜介导的现象，这种蛋白质主要集中在AS 这一原型可能会比其他原型更快地产生更基本的洞察力。

The structure of bacteriorhodopsin, a 27,000 dalton membrane protein from purple membrane of Halobacterium halobium is to be defined by high resolution electron diffraction of membranes, and of membranes with heavy metal groups covalently attached. Building on our previous studies, we can now determine the site of attachment of such labels in sequence and structure. Thus a primary objective is to determine the order and orientation in which the seven transmembrane sequences occurs in the structure. We have previously determined the phases of electron diffraction amplitudes to 3.7 Angstroms experimentally (i.e., from images), and recorded diffraction to 2.65 Angstroms at -120 C and this is crucial to difference mapping. We have defined an extended resolution 7x10 Angstrom 3-D structure that shows additional features helpful in building a model of the protein structure: Having defined the retinal attachment site in sequence, we will identify side chains involved in the mechanism of proton pumping using site-specific mutagenesized proteins, and using mutants under study in a closely complementary proposal of H. Boyer at UCSF. The site-specific changes will be based on structure, and both structural change and functional variance will be assessed to define a mechanism of light-energy conversion, insertion into the membrane, membrane protein stability, the role of prolines, the role of peptides between helices in the aqueous phase, and with the end goal of understanding the mechanisms in an archetype of transmembrane protein-mediated phenomena. Increasing similarities to rhodopsin in the eye is emerging. An overall goal is to understand membrane mediated phenomena, and this protein is focussed on as an archetype likely to yield much fundamental insight sooner than others.