MYELIN PO GLYCOPROTEIN: STRUCTURE & ADHESIVE MECHANISMS

说明(申请人摘要)：总体目标 这个应用是为了定义髓鞘的分子组织，多样的 稳定其多层鞘的粘合机制，以及哪些缺陷 在其组织和分子组成上可能导致髓鞘障碍或 脱髓鞘，如发生在某些周围神经病和多发性 硬化症。这种方法是基于X射线结果的相关性。 结晶学和溶液散射、膜衍射和电子 显微镜。具体目标，重点是结构和作用 周围神经髓鞘主要跨膜蛋白(P0-糖蛋白) 主要内容有：(1)测定P0-糖蛋白的三维结构 人类和非洲爪哇。被分析的蛋白质将包括重组分子。 具有天然氨基酸序列的，以及具有特定氨基酸序列的 已知的在人类周围神经病中发生的序列改变。这些 研究将提供有关P0的原子结构和晶体的信息 可能对此起作用的接触或粘连接口 蛋白质在髓鞘中的形成和稳定。(2)刻画 最近邻P0分子间的蛋白质-蛋白质相互作用 利用小角X射线散射的膜模拟环境。膜 蛋白质在极低的洗涤剂水溶液中会被增溶。 浓缩和溶液散射将使用同步加速器进行 X射线源。这些研究将提供有关相互蛋白的信息。 P0分子在更紧密的环境中进行的分子接触 类似于它的自然环境(髓鞘膜的脂双层) 比一块水晶还多。(3)膜-膜相互作用的评价 非洲爪哇周围神经的髓鞘。PH-和离子的测定 解剖周围膜结构和填充物的强度依赖性 在不同的环境中孵化的神经将提供强大的约束 为了测试关于P0在两种情况下的黏附机制的假设 胞质和胞外膜的对位。这种层级结构 实验目标将使研究人员能够独特地关联 从原子到分子，再到膜水平的结构数据，以及 从而有助于理解膜的结构生物学 对健康和疾病都有重要作用的蛋白质。

DESCRIPTION (Applicant's abstract): The overall objective of this application is to define the molecular organization of myelin, the diverse adhesive mechanisms that stabilize its multilamellar sheath, and what defects in its organization and molecular constituents may lead to dysmyelination or demyelination such as occur in certain peripheral neuropathies and in multiple sclerosis. The approach is based on a correlation of results from X-ray crystallography and solution scattering, membrane diffraction, and electron microscopy. The specific aims, which are focused on the structure and role of the major transmembrane protein of peripheral nerve myelin (P0-glycoprotein) are: (1) to determine the three-dimensional structure of P0-glycoprotein for human and Xenopus. The proteins analyzed will include recombinant molecules having the native amino acid sequence, as well as those having specific sequence alterations known to occur in human peripheral neuropathies. These studies will inform about the atomic structure of P0 and about the crystal contacts or adhesion interfaces that may be responsible for the role of this protein in myelin formation and stability. (2) To characterize the protein-protein interactions between nearest-neighbor P0 molecules in a membrane mimetic environment using small-angle X-ray scattering. The membrane protein will be solubilized in aqueous solutions of detergents at very low concentration, and solution scattering will be undertaken using a synchrotron X-ray source. These studies will provide information about the interprotein molecular contacts that P0 molecules make in a milieu that more closely resembles its native environment (the lipid bilayer of the myelin membrane) than does a crystal. (3) To evaluate the membrane-membrane interactions in myelin of Xenopus peripheral nerves. Determining the pH- and ionic strength-dependence of membrane structure and packing in dissected peripheral nerves that have been incubated at different will provide strong constraints for testing hypotheses about the adhesion mechanisms of P0 at both the cytoplasmic and extracellular membrane appositions. This hierarchy of experimental objectives will allow the investigator to uniquely correlate structural data from the atomic to the molecular, to the membrane level, and thus contribute to an understanding of the structural biology of a membrane protein that figures significantly in both health and disease.