Venneker G T, Asghar S S
Department of Dermatology, University of Amsterdam, The Netherlands.
Exp Clin Immunogenet. 1992;9(1):33-47.
CD59 is a recently discovered complement (C) regulatory protein. Three activities of CD59 have been recognized so far. It can downregulate the activation of the C cascade at membrane attack complex formation stage, it participates in T-cell rosette formation with erythrocytes and appears to be necessary for T-cell activation. CD59 is broadly distributed on cells of various organs and this is compatible with its function of protecting cells and tissues from incidentally activated autologous C. CD59 is encoded by a single gene residing on chromosome 11. The entire sequence of CD59 cDNA is known, from which the amino acid structure of CD59 has been deduced. Mature CD59 is made up of 103 amino acids. It has two potential N-glycosylation sites. Carbohydrate constitutes about 20% of the molecular mass of CD59. The protein part of the molecule is covalently linked to an oligosaccharide which, in turn, is glycosydically linked to phosphatidylinositol (PI). CD59 is anchored to the cells via PI moiety. The fine structure of the PI anchor of CD59 has not yet been established. Decreased expression of CD59 has been shown in two diseases. In paroxysmal nocturnal hemoglobinuria, erythrocytes (type III) lacking CD59 (and other PI proteins) have susceptibility to lysis by membrane attack complex. In psoriasis, expression of CD59 (and CD55) is drastically decreased in psoriatic lesions, presumably due to PI cleavage involving signal transduction mechanism(s) leading to increased proliferation of various cell types in lesional skin.
CD59是一种最近发现的补体（C）调节蛋白。迄今为止，已识别出CD59的三种活性。它可以在膜攻击复合物形成阶段下调补体级联反应的激活，它参与红细胞的T细胞玫瑰花结形成，并且似乎是T细胞激活所必需的。CD59广泛分布于各种器官的细胞上，这与其保护细胞和组织免受偶然激活的自身补体影响的功能是相符的。CD59由位于11号染色体上的单个基因编码。已知CD59 cDNA的完整序列，由此推导出了CD59的氨基酸结构。成熟的CD59由103个氨基酸组成。它有两个潜在的N-糖基化位点。碳水化合物约占CD59分子质量的20%。分子的蛋白质部分与一个寡糖共价连接，而该寡糖又通过糖苷键与磷脂酰肌醇（PI）相连。CD59通过PI部分锚定在细胞上。CD59的PI锚定的精细结构尚未确定。在两种疾病中已显示出CD59表达降低。在阵发性夜间血红蛋白尿中，缺乏CD59（和其他PI蛋白）的红细胞（III型）对膜攻击复合物的裂解敏感。在银屑病中，银屑病皮损中CD59（和CD55）的表达急剧下降，可能是由于涉及信号转导机制的PI裂解导致皮损皮肤中各种细胞类型的增殖增加。
