FUNCTIONS, STRUCTURE, AND REGULATION OF RECEPTORS FOR CELL ADHESION PROTEINS

细胞通过特定的方式与细胞外基质分子相互作用 感受器。我们已经对膜结合分子进行了表征 纤维连接蛋白和胶原蛋白。生物合成、调节和 对纤维连接蛋白受体的功能进行了研究。测试版 发现合成了小鼠和人类受体的亚单位。 作为较小的前体，需要较长的成熟期 涉及天冬酰胺连接的寡糖。成熟带来的结果 在激活纤维连接蛋白结合功能和分泌到 细胞表面。α和β亚基的水平 人纤维连接蛋白受体受转化生长调控 B因子，诱导合成20-40倍。纤维连接蛋白 细胞表面的受体被证明存在于 跨膜取向。它们常常迅速扩散。 迁移胚胎细胞和禽类或人类肿瘤细胞，但 聚集在固定细胞的贴壁部位。这些 分布与受体无关。 磷酸化。纤维连接蛋白受体的作用在 胚胎两栖动物原肠形成与人体血小板功能。 针对该受体的抗体阻断了原肠形成和血小板 黏附于纤维粘连蛋白。受体与血小板相对应 糖蛋白IC-IIa，参与非依赖激活 血小板附着在含有纤维连接蛋白的底物上。一个 癌变后减少的蛋白质是 以生化为特征的。它是一种球状单体，富含 碱性氨基酸，具有独特的氨基末端36个残基序列 含有一个与其他热量无关的新的7-聚体串联重复序列 休克蛋白。热休克诱导的mRNA水平，通过检测 体外翻译和Northern印迹分析。两个推定 该hsp47蛋白的顺序生物合成前体是。 经鉴定，这两种病毒都具有完全的生物活性 与胶原蛋白配体；这种直接的功能形成了对比 具有激活纤维连接蛋白受体的要求。

Cells interact with extracellular matrix molecules by specific receptors. We have characterized membrane binding molecules for fibronectin and collagen. The biosynthesis, regulation, and function of fibronectin receptors were characterized. The beta subunit of mouse and human receptors were found to be synthesized as smaller precursors that required a lengthy maturation period involving asparagine-linked oligosaccharides. Maturation resulted in an activation of fibronectin-binding function and secretion onto the cell surface. Levels of both alpha and beta subunits of the human fibronectin receptor were regulated by transforming growth factor B, which induced synthesis 20- to 40-fold. Fibronectin receptors on the cell surface were shown to exist in a transmembrane orientation. They are often diffuse on rapidly migrating embryonic cells and avian or human tumor cells, but clustered at adhesion sites of stationary cells. These distributions were shown to be independent of receptor phosphorylation. Roles for the fibronectin receptor were shown in embryonic amphibian gastrulation and human platelet function. Antibodies against the receptor blocked gastrulation and platelet adhesion to fibronectin. The receptor corresponds to platelet glycoprotein Ic-IIa, and is involved in activation-independent attachment of platelets to fibronectin-containing substrates. A protein that was decreased after malignant transformation was characterized biochemically. It is a globular monomer enriched in basic amino acids, with a unique amino-terminal 36-residue sequence containing a novel 7-mer tandem repeat unrelated to other heat shock proteins. Heat shock induces levels of mRNA as detected by in vitro translation and Northern blot analysis. Two putative sequential biosynthetic precursors of this hsp47 protein were. identified, both of which were fully biologically active in binding to a collagenous ligand; this immediate functionality contrasts with the requirement for activation of the fibronectin receptor.