Bahou W F, Potter C L, Mirza H
Department of Medicine, State University of New York at Stony Brook 11794-8151.
Blood. 1994 Dec 1;84(11):3734-41.
The integrin VLA-2 (alpha 2 beta 1), generally considered to represent the specific collagen receptor on human endothelial cells, contains an alpha 2-subunit inserted I domain with structural similarity to the type A domains found within the recently described superfamily of receptor-ligand recognition proteins. This region of the cDNA has now been isolated and used for molecular and functional characterization of this heterodimeric receptor complex. Comparative sequence analysis with the porcine homologue revealed 93% amino acid sequence identity, suggestive of a developmentally conserved function. To complete structure/function studies, this region of the human cDNA was expressed as a chimeric protein in Escherichia coli, and a rabbit polyclonal antibody (anti-I domain) was used to study determinants of endothelial cell attachment and spreading in vitro. Quantifiable and visual disruption of endothelial cell attachment to gelatin, type I collagen, and laminin was evident using the specific anti-I domain antibody, with minimal inhibitory effects demonstrable using fibronectin or fibrinogen matrices. Therefore, these data would suggest that the alpha 2 beta 1 I domain confers ligand-binding specificity for both known alpha 2 beta 1 substrates (laminin and collagen), and that this region subserves a regulatory function in the molecular processes controlling endothelial cell attachment and spreading in vitro.
整联蛋白VLA-2（α2β1）通常被认为是人类内皮细胞上的特异性胶原受体，其α2亚基插入的I结构域与最近描述的受体-配体识别蛋白超家族中的A型结构域具有结构相似性。现在已分离出该cDNA区域，并用于该异二聚体受体复合物的分子和功能表征。与猪同源物的比较序列分析显示氨基酸序列同一性为93%，提示其功能在进化过程中保守。为了完成结构/功能研究，将人类cDNA的该区域在大肠杆菌中表达为嵌合蛋白，并使用兔多克隆抗体（抗I结构域）研究体外内皮细胞附着和铺展的决定因素。使用特异性抗I结构域抗体可明显观察到内皮细胞与明胶、I型胶原和层粘连蛋白的附着受到可量化和可视化的破坏，而使用纤连蛋白或纤维蛋白原基质时则显示出最小的抑制作用。因此，这些数据表明α2β1 I结构域赋予了对已知α2β1底物（层粘连蛋白和胶原）的配体结合特异性，并且该区域在体外控制内皮细胞附着和铺展的分子过程中发挥调节功能。
