Agre P, Cartron J P
Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Blood. 1991 Aug 1;78(3):551-63.
The RBC Rh antigens are of large clinical importance, but until recently have been poorly understood at a molecular level. The Rh polypeptides are a family of nonglycosylated Mr 30- to 32-Kd transmembrane proteins that are core structural components of the Rh antigens and have been purified and partially characterized biochemically. Rh polypeptides are present in RBCs from normal humans and other mammalian species and are probably required for normal membrane integrity, because they appear to be missing from the RBCs of the rare Rhnull individuals that express several membrane defects. The Rh polypeptides contain an exofacial free sulfhydryl that is important for Rh antigenic reactivity and several intracellular sulfhydryls that appear to be palmitylated, but most of the molecule appears to reside between the leaflets of the phospholipid bilayer. The cDNA coding for a 416-amino acid Rh polypeptide was recently isolated but was not found to share sequence homology with any known protein, and Northern analysis indicated that Rh is erythroid specific. The Rh antigens within the native membranes are thought to exist as a complex of Rh polypeptides and multiple other membrane components, including certain Rh-related glycoproteins. While it is thought that this assembly may be important for the Rh antigenic reactivity, the structural basis of this remains to be established. While the physiologic role of Rh is yet to be defined, several clues indicate that it may play a role in the organization of membrane phospholipids or synthesis or membrane expression of various glycoproteins. While our knowledge of Rh is still very incomplete, recent research has significantly advanced the molecular understanding of these important blood group antigens.
红细胞Rh抗原具有重大临床意义，但其分子水平的情况直到最近才得到较好的理解。Rh多肽是一类非糖基化的分子量为30至32千道尔顿的跨膜蛋白，是Rh抗原的核心结构成分，已得到纯化并进行了部分生化特性分析。Rh多肽存在于正常人及其他哺乳动物物种的红细胞中，可能对维持正常膜完整性至关重要，因为在表现出多种膜缺陷的罕见Rh缺失个体的红细胞中似乎没有这种多肽。Rh多肽含有一个对Rh抗原反应性很重要的细胞外游离巯基以及几个似乎被棕榈酰化的细胞内巯基，但该分子的大部分似乎位于磷脂双层的小叶之间。最近分离出了编码一种416个氨基酸的Rh多肽的cDNA，但未发现它与任何已知蛋白质具有序列同源性，Northern分析表明Rh具有红细胞特异性。天然膜中的Rh抗原被认为是以Rh多肽与多种其他膜成分（包括某些Rh相关糖蛋白）的复合物形式存在。虽然认为这种组装可能对Rh抗原反应性很重要，但其结构基础仍有待确定。虽然Rh的生理作用尚未明确，但有几条线索表明它可能在膜磷脂的组织或各种糖蛋白的合成或膜表达中起作用。虽然我们对Rh的了解仍然非常不完整，但最近的研究在分子层面上显著推进了对这些重要血型抗原的认识。
