Honscha W, Ottallah M, Kistner A, Platte H, Petzinger E
Institute of Pharmacology and Toxicology, University of Giessen, Germany.
Biochim Biophys Acta. 1993 Dec 12;1153(2):175-83. doi: 10.1016/0005-2736(93)90403-m.
Protein disulfide isomerase (PDI) was considered to be involved in the hepatic uptake of certain organic anions because the protein is photoaffinity labeled by photolabile derivatives of the bile acid taurocholate. Several lines of evidences including photoaffinity labeling experiments indicated a close relationship between the uptake of bile acids and the organic anion bumetanide. The possible involvement of PDI in hepatic transport processes of these organic anions was tested with polyclonal antibodies raised against a PDI-beta-galactosidase fusion protein. Western blot analysis and immunofluorescence of intact hepatocytes showed that protein disulfide isomerase is located in sinusoidal rat liver plasma membranes. This protein is immunologically identical with microsomal PDI prepared from bovine liver. The plasma membrane form of PDI is, however, not labeled by photoactivated bumetanide as revealed by two-dimensional gel electrophoresis. These results indicate that, although a membrane-bound form of the PDI is present in the sinusoidal plasma membrane of rat hepatocytes, this protein is not involved in the hepatocellular uptake of the organic anion bumetanide.
蛋白质二硫键异构酶（PDI）被认为参与了某些有机阴离子的肝脏摄取，因为该蛋白质可被胆汁酸牛磺胆酸盐的光不稳定衍生物进行光亲和标记。包括光亲和标记实验在内的多项证据表明，胆汁酸摄取与有机阴离子布美他尼之间存在密切关系。使用针对PDI-β-半乳糖苷酶融合蛋白产生的多克隆抗体，测试了PDI在这些有机阴离子肝脏转运过程中的可能参与情况。完整肝细胞的蛋白质印迹分析和免疫荧光显示，蛋白质二硫键异构酶位于大鼠肝脏的窦状质膜中。该蛋白质与从牛肝脏制备的微粒体PDI在免疫学上相同。然而，二维凝胶电泳显示，PDI的质膜形式未被光活化的布美他尼标记。这些结果表明，尽管大鼠肝细胞窦状质膜中存在膜结合形式的PDI，但该蛋白质不参与有机阴离子布美他尼的肝细胞摄取。
