MOLECULAR BASIS OF CADHERIN MEDIATED CELL ADHESION

描述（由申请人提供）：选择性细胞粘附对于 许多多细胞生命的基本生物过程。的 钙粘蛋白包括已知最大的细胞粘附蛋白家族之一， 它们的功能在形态发生的无数事件中至关重要， 实体组织的内环境稳定。尽管如此， 钙粘蛋白介导的细胞粘附及其调节仅知之甚少。 该项目的长期目标是了解结构， 在原子水平上详细描述钙粘蛋白的功能。为了实现这一目标，我们 将使用X射线晶体学来确定 处于关键功能状态的经典钙粘蛋白。功能相关假说 将通过定点诱变来测试衍生自这些结构的突变体， 细胞粘附实验。 经典的钙粘蛋白，包括N-、E-和C-钙粘蛋白，是迄今为止最常见的钙粘蛋白。 最好的特点。我们和其他人认为，一个关键的监管 cis-（相同细胞）可能提供钙粘蛋白粘附机制 二聚化。然而，钙粘蛋白实现其主要粘附功能 通过细胞间的相互作用。这些反式分子的分子细节 迄今为止，钙粘蛋白分子之间的粘附界面仍是未知的。 为了进一步阐明钙粘蛋白细胞粘附的分子基础，我们将（1） 确定整体、功能、二聚体的三维结构 C-cadherin的胞外结构域。虽然小的非功能性结构 钙粘蛋白的片段已经确定之前，我们现在将可视化 完整的功能性胞外区。(2)基于这种结构， 目前正在确定过程中，我们将执行基于细胞的 定点诱变和粘附实验来测试基于结构的 从结构中推导出的功能假设。

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.