Bates P A, Hermes I, Dwyer D M
Department of Zoology, University of Glasgow, U.K.
Mol Biochem Parasitol. 1990 Mar;39(2):247-55. doi: 10.1016/0166-6851(90)90063-r.
Monensin, an inhibitor of Golgi function, was used to investigate the role of this cell compartment in the glycosylation of Leishmania donovani promastigote secretory acid phosphatase (EC 3.1.3.2). Monensin-treated cells demonstrated morphological changes in the Golgi complex and secreted enzyme with an altered electrophoretic mobility: two discrete bands of approximately 95 and 110 kDa were found, as compared to the heterodisperse nature of the enzyme from untreated controls. Chemical deglycosylation by mild acid hydrolysis resulted in a similar effect on the electrophoretic mobility of purified extracellular enzyme. Acid phosphatase was also treated with N-glycosidase F (EC 3.5.1.52) to remove N-linked oligosaccharides. The altered lectin-binding properties of the enzyme after these two treatments demonstrated that an unusual type of galactose-containing acid-labile carbohydrate was present in secretory acid phosphatase in addition to the N-linked oligosaccharides. Further, experiments with 32P-labelled enzyme indicated that phosphodiester bonds were the structural component responsible for the sensitivity of this carbohydrate to mild acid hydrolysis. Cumulatively, these results demonstrated that a novel form of Golgi-mediated posttranslational modification had occurred to the secretory acid phosphatase presumably by the addition of an acid-labile phosphoglycan.
莫能菌素是一种高尔基体功能抑制剂，被用于研究该细胞器在杜氏利什曼原虫前鞭毛体分泌性酸性磷酸酶（EC 3.1.3.2）糖基化过程中的作用。经莫能菌素处理的细胞，高尔基体复合体呈现出形态变化，且分泌的酶电泳迁移率发生改变：与未处理对照组酶的多分散性质相比，发现了两条分别约为95 kDa和110 kDa的离散条带。通过温和酸水解进行化学去糖基化，对纯化的细胞外酶的电泳迁移率产生了类似影响。酸性磷酸酶还用N-糖苷酶F（EC 3.5.1.52）处理以去除N-连接的寡糖。这两种处理后该酶凝集素结合特性的改变表明，除了N-连接的寡糖外，分泌性酸性磷酸酶中还存在一种不寻常的含半乳糖的酸不稳定碳水化合物。此外，用32P标记酶的实验表明，磷酸二酯键是导致这种碳水化合物对温和酸水解敏感的结构成分。综合来看，这些结果表明，分泌性酸性磷酸酶可能通过添加一种酸不稳定的磷酸聚糖，发生了一种新型的高尔基体介导的翻译后修饰。
