BIOLOGY OF THE HUMAN GLYCOPHORIN BLOOD GROUP ANTIGENS

血糖素A是人红细胞表面的主要糖蛋白 并同时含有N-和O-连接的低聚糖。尽管在结构上 很好的特点，相对鲜为人知的是 血糖素A的生物合成或糖基化在易位中的作用 以及这种分子的表面表达。血糖素A在体内很重要。 输血医学的实践，因为它携带了几个不同的人 血型抗原，而针对这些抗原的抗体可引起溶血 输血反应、新生儿溶血性疾病和自身免疫 溶血性贫血。然而，很少有研究对罚款进行审查。 人多克隆抗体和鼠单抗结合的特异性 到这个分子。血糖素A也具有重要的医学价值，因为它 可以作为红细胞表面的受体，促进红细胞膜的侵入 恶性疟原虫裂殖子。由于……的困难 获得氨基酸有明确变异的突变体血糖素A分子 酸序列和寡糖结构，详细了解 这种红血球与寄生虫的相互作用目前还不存在。 目前这项提议的目标是研究人类的生物学 血型糖蛋白抗原： 1)确定N-和O-连接的寡糖在 血糖素A的细胞内转运和表面表达， 2)检测血糖素A之间相互作用的细微特异性 以及人和鼠的抗体，以及 3)测定血糖素A的多肽和碳水化合物部分 被人类疟疾寄生虫识别。 这些目标将通过稳定地创建一系列细胞系来实现 分别用野生型或变异型血糖素A基因进行表达。突变型 血糖素A的cDNAs将通过定点突变的方式构建 聚合酶链式反应。通过在两个正常组织中表达这些cDNA 中国仓鼠卵巢成纤维细胞和糖基化缺陷细胞， 将有可能产生不同的血糖素A分子 在氨基酸和碳水化合物序列中。两个完整的细胞系 从细胞系中提纯的血糖素A蛋白将被用于 来解决这三个目标。

Glycophorin A is the major glycoprotein on the human red blood cell surface and contains both N- and O-linked oligosaccharides. Although structurally well characterized, relatively little is known concerning either the biosynthesis of glycophorin A or the role of glycosylation in translocation and surface expression of this molecule. Glycophorin A is important in the practice of transfusion medicine since it carries several different human blood group antigens, and antibodies to these antigens can cause hemolytic transfusion reactions, hemolytic disease of the newborn, and autoimmune hemolytic anemia. However, there have been few studies examining the fine specificity of binding of human polyclonal or mouse monoclonal antibodies to this molecule. Glycophorin A is also of medical importance because it can serve as the red blood cell surface receptor for the invasion of Plasmodium falciparum malaria merozoites. Due to the difficulty in obtaining mutant glycophorin A molecules with defined variations in amino acid sequence and oligosaccharide structure, a detailed understanding of this red blood cell-parasite interaction is not yet available. The goals of the current proposal are to study the biology of the human blood group glycophorin antigens by: 1) determining the importance of the N- and O-linked oligosaccharides in intracellular trafficking and surface expression of glycophorin A, 2) examining the fine specificity of the interactions between glycophorin A and human and mouse antibodies, and 3) determining the peptide and carbohydrate portions of glycophorin A which are recognized by human malaria parasites. These goals will be achieved by creating a series of cell lines stably transfected with either wild type or variant glycophorin A cDNA. Mutant glycophorin A cDNAs will be constructed by site-directed mutagenesis using the polymerase chain reaction. By expressing these cDNAs in both normal Chinese hamster ovary fibroblasts and those with defects in glycosylation, it will be possible to create variant glycophorin A molecules which differ in both amino acid and carbohydrate sequence. Both the intact cell lines and glycophorin A proteins purified from the cell lines will then be used to address these three goals.