The Structure and Function of Retinal Pigment Epithelial Cells

以小鼠为免疫动物，制备了抗鸡和牛视网膜色素上皮(RPE)细胞的单抗。用分子生物学和细胞生物学方法分析了其中S5D8和RPE7的特性：S5D8：抗原蛋白分子量为63 kDa。该基因全长2510bp，开放阅读框为1599bp，有2个多聚腺苷酸化信号。氨基酸残基为533个，分子大小为60.9 kDa。该蛋白有3个糖基化位点。它既没有信号肽，也没有膜膨胀区。该基因的大小约为2.9kb。将开放阅读框转染成纤维细胞，内质网S5D8.2染色；PRE7：RPE7定位于视网膜色素上皮和视网膜米勒细胞的质膜上。这一结果似乎表明RPE7蛋白参与了视网膜的支持功能。经Western blotting分析，该蛋白的相对分子质量为40-45 kDa。RPE7有一个271个氨基酸残基的开放阅读框，有3个糖基化位点，并且有一个膜扩展的疏水区。同源性研究表明，RPE7蛋白属于一种新型的免疫球蛋白超家族，其中一种被命名为EMMPRIN。EMMPRIN参与细胞外基质的重塑，并在癌细胞的转移中发挥作用。用酶谱法检测培养的牛视网膜色素上皮中金属蛋白酶活性。培养上清液中含有明胶酶A，加入抗RPE7抗体后，明胶酶A的活性增强。这一结果表明，在某些病理条件下，RPE7在RPE的外段吞噬和动员中起重要作用。

Monoclonal antibodies were raised against chick and bovine retinal pigment epithelial (RPE) cells using mice as immune animal. Among the monoclonal antibodies, S5D8 and RPE7 were analyzed their characters by means of molecular and cellular biological methods.1) ; S5D8 : The antgen protein has molecular weight of 63kDa. The whole length of cDNA is 2510bp, open reading frame being 1599bp with 2 olyadenylation signals. Amino acid residues are 533 and their molecular size being 60.9kDa. The protein has 3 glycosylation sites. It has neither signal peptide nor membrane expanding region. The size of mRNA is about 2.9kbases. The open reading frame was transfected to cultured fibroblasts, the endoplasmic reticula of which were stained with S5D8.2) ; PRE7 : The localization of RPE7 was on the plasma membranes of RPE and Muller cells of neural retina. This result seem to suggest the protein RPE7 is involved in the supporting function of the retina. The protein has molecular weight of 40-45kDa by Western blotting. RPE7 has an open reading frame of 271 amino acid residues, 3 glycosylation sitesand is found to have a membrane expanding hydrophobic region. Homology research of this cDNA sequences revealed that RPE7 protein belongs to a novel type of immunoglobulin superfamily, one of which has been named EMMPRIN.EMMPRIN is involved in the remodeling of extrcellular matrix and plays a role in the metastasis of cancer cells. Metalloproteinase activity was assayd with cultured bovine RPE by zymography. The culture supernatant contained gelatinaseA,the activity of which became higher when anti-RPE7 antibody was added to the culture medium. It is concluded, from this result, that RPE7 plays an important role in the phagocytosis of outer segment and mobilization of RPE at some pathlogical conditions.