MACROMOLECULAR INTERACTION IN CELL ATTACHMENT AND MATRIX ASSEMBLY

纤维连接蛋白是一种很大的蛋白质(Mr约为25万道尔顿)，它介导 细胞与细胞外基质的相互作用。分子 以二硫键连接的二聚体的形式存在，这种二聚体是拉长的和灵活的 参与组织中一系列复杂的大分子相互作用 影响细胞黏附和迁移的物质。这个经过充分研究的矩阵 蛋白质由多个重复模块组成，大约40-90个 可分为三种同源单位的氨基酸： 类型一、类型二和类型三.这些模块的集群构成单独的 多功能分子的全活性结构域。蛋白 结晶学将被用来研究两个化合物的分子基础 纤维连接蛋白的生物学作用：细胞黏附和基质组装。类型 III模块是中介领域中的结构构建块 这两个过程。模块III/10含有精氨酸-甘氨酸-天冬氨酸 α5beta1细胞表面黏附识别的酸(RGD)序列 受体(整合素)。模块III/1绑定到 纤维连接蛋白的氨基和羧基自结合模式 在细胞外基质形成之前。模块的一个片段 III/1(III/1-C)与纤维连接蛋白(模块III/11)结合并增强 纤维粘连蛋白粘附性。基质组装的正常过程是 破坏了致瘤细胞，并缺乏稳定的蓄积 基质可能会影响癌细胞的侵袭特性。重组 纤维连接蛋白片段(即，包括III/10、III/1、III/1-C和 III/11模块)以及多模块碎片(即III/10-11、III/8- 10，III/8-11)将被结晶。此外，模块IIICS存在于 人纤维连接蛋白的选择性剪接变异体，由 将研究α4beta1整合素。原子模型源自 这些结晶学分析将被用来理解细胞附着 以及允许肿瘤侵袭和转移的基质组装缺陷以及 开始构建纤维连接蛋白的超结构图像 相邻模块和远距离模块的交互。

Fibronectin is a large protein (Mr about 250,000 daltons) that mediates the interaction of cells with the extracellular matrix. The molecule exists as a disulfide linked dimer that is elongated and flexible and participates in a complex set of macromolecular interactions in tissue that influence cell adhesion and migration. This well-studied matrix protein consists of multiple repeating modules of approximately 40-90 amino acids that can be classified into three types of homology units: types I, II and III. Clusters of these modules constitute individual fully active domains of the multifunctional molecule. Protein crystallography will be used to study the molecular basis for two biological roles of fibronectin: cell adhesion and matrix assembly. Type III modules are structural building blocks in the domains that mediate these two processes. Module III/10 contains an arginine-glycine-aspartic acid (RGD) sequence recognized by the alpha5beta1 cell surface adhesion receptor (integrin). Module III/1 binds to the type I modules at the amino- and carboxyl regions of fibronectin in a self-association mode prior to the formation of extracellular matrix. A fragment of module III/1 (III/1-C) binds to fibronectin (module III/11) and enhances fibronectin adhesiveness. The normal process of matrix assembly is disrupted in tumorigenic cells, and the lack of a stable accumulated matrix may influence the invasive properties of cancer cells. Recombinant fragments of fibronectin (i.e., including III/10, III/1, III/1-C and III/11 modules) as well as multimodule fragments (i.e., III/10-11, III/8- 10, III/8-11) will be crystallized. Also, module IIICS that exists in alternatively spliced variants of human fibronectin and is recognized by the alpha4beta1 integrin will be studied. Atomic models derived from these crystallographic analyses will be used to understand cell attachment and matrix assembly defects that permit tumor invasion and metastasis and to begin to construct a supra-structural image of fibronectin considering interactions of adjacent as well as distant modules.