MOLECULAR BASIS OF CADHERIN MEDIATED CELL ADHESION

描述(由申请人提供)：选择性细胞黏附对 多细胞生命的许多基本生物学过程。这个 钙粘附素是已知的最大的细胞黏附蛋白家族之一， 它们的功能在形态发生的无数事件中都是至关重要的 固体组织的动态平衡。尽管如此，潜在的分子机制 钙粘附素介导的细胞黏附及其调控还知之甚少。 这个项目的长期目标是了解结构和 钙粘附素在原子细节水平上的功能。为了实现这一目标，我们 将使用X射线结晶学来确定其三维结构 处于关键功能状态的经典钙粘附素。与函数相关的假设 从这些结构衍生出来的将通过定点突变和 细胞黏附实验。 经典的钙粘附素，包括N-、E-和C-钙粘蛋白，到目前为止是 最有特色的。我们和其他人建议，一个关键的监管机构 钙粘附素的黏附机制可能由顺式(同一细胞)提供。 二聚化。然而，钙粘附素实现了它们的主要黏附功能 通过反式(细胞对细胞)相互作用。这些反式基因的分子细节 到目前为止，钙粘附素分子之间的粘附性界面仍然未知。 为了进一步阐明钙粘附素细胞黏附的分子基础，我们将(1) 确定整体、官能团、二聚体的三维结构 C-钙粘蛋白的胞外区。而小而无功能的结构 之前已经确定了钙粘附素的片段，现在我们将可视化一个 完整的、有功能的胞外区。(2)基于这种结构， 目前正在确定的过程中，我们将执行基于细胞的 定点诱变和黏附实验测试基于结构的 从结构中衍生出的功能假说。

DESCRIPTION (provided by applicant): Selective cell adhesion is crucial for many of the biological processes fundamental to multicellular life. The cadherins comprise one of the largest known families of cell adhesion proteins, and their function is critical in countless events in the morphogenesis and homeostasis of solid tissues. Nonetheless, the molecular mechanisms underlying cadherin-mediated cell adhesion and its regulation are only poorly understood. The long-term objective of this project is to understand the structure and function of cadherins at an atomic level of detail. In pursuit of this goal we will use X-ray crystallography to determine the three-dimensional structures of classical cadherins in key functional states. Function-related hypotheses derived from these structures will be tested by site-directed mutagenesis and cell-based adhesion experiments. The classical cadherins, which include N-, E-, and C-cadherins, are so far the best characterized. We and others have suggested that a critical regulatory mechanism for cadherin adhesion may be provided by cis- (same cell) dimerization. However, cadherins achieve their primary adhesive function through trans (cell to cell) interactions. The molecular details of these trans adhesive interfaces between cadherin molecules thus far remain unknown. To further elucidate the molecular basis of cadherin cell adhesion, we will (1) determine the three-dimensional structure of the whole, functional, dimeric extracellular domain of C-cadherin. While structures of small non-functional fragments of cadherins have been determined previously, we will now visualize a complete, functional extracellular domain. (2) Based on this structure, which is currently in the process of being determined, we will perform cell-based site-directed mutagenesis and adhesion experiments to test structure-based functional hypotheses derived from the structure.