STRUCTURAL ANALYSES AND FUNCTIONS OF RECEPTORS FOR CELL ADHESION PROTEINS

细胞似乎与结构和调节分子相互作用 细胞外基质通过特定的受体。我们已经分析了 可能是两种主要糖蛋白的受体，纤维连接蛋白和胶原。 一种膜糖蛋白复合体，由三个组分组成 大约有140,000个道尔顿被证明部分地与 细胞外纤维连接蛋白及其与细胞内α-肌动蛋白的关系 微丝束。抗该复合体的单抗被阻断 细胞与纤维连接蛋白的黏附，以及底物附着性抗体本身可以 模拟纤维连接蛋白介导的扩散。此推定的组件 纤维连接蛋白受体复合体被分离出来，并显示出三个不同的 酸性唾液酸糖蛋白非共价结合成凝胶 很复杂。其他研究表明神经节苷脂与神经节细胞的组织有关 细胞外纤维连接蛋白纤维，并显示了这些纤维的定位 细胞表面附着部位的脂类。可能的 胶原蛋白的占据对纤维连接蛋白受体功能的调节 对受体进行了研究。细胞与胶原蛋白或其α1的孵育(I) 链被发现抑制纤维连接蛋白受体的一个特定亚群 以非竞争性方式运作。细胞铺展和吞噬功能 抑制，而与纤维连接蛋白涂层的直接结合和细胞附着 底物未受影响。我们未来的目标将是分析 纤维连接蛋白和胶原受体的结构和功能。 单抗和多克隆抗体将用于受控 蛋白水解性切割，以确定每个的结构和功能结构域。 转化后它们的分布和磷酸化的变化 并将建立热休克。重建实验和 对生物功能所需的其他分子的分析应该提供一个 进一步了解它们的作用机制。

Cells appear to interact with structural and regulatory molecules in the extracellular matrix by means of specific receptors. We have analyzed putative receptors for two major glycoproteins, fibronectin and collagen. A membrane glycoprotein complex consisting of three components of approximately 140,000 daltons each was shown to co-localize partially with extracellular fibronectin and with intracellular Alpha-actinin in microfilament bundles. Monoclonal antibodies against this complex blocked cell adhesion to fibronectin, and substrate-attached antibody alone could mimic fibronectin-mediated spreading. The components of this putative fibronectin receptor complex were isolated and shown to be three distinct acidic sialoglycoproteins associated noncovalently into an olgomeric complex. Other studies implicated gangliosides in cellular organization of extracellular fibronectin fibrils, and showed a localization of these lipids at sites of their attachment to the cell surface. Possible modulation of fibronectin receptor function by occupancy of the collagen receptor was explored. Incubation of cells with collagen or its Alpha1(I) chain was found to inhibit a specific subset of fibronectin receptor functions in non-competitive fashion. Cell spreading and phagycytosis were inhibited, while direct binding and cell attachment to fibronectin-coated substrates were unaffected. Our future objectives will be to analyze the structures and functions of the receptors for fibronectin and collagen. Monoclonal and polyclonal antibodies will be used with controlled proteolytic cleavage to define structural and functional domains of each. Alterations in their distribution and phosphorylation after transformation and heat shock will be established. Reconstitution experiments and analyses of other molecules needed for biological function should provide a further understanding of their mechanisms of action.