Van Wye J, Ghori N, Webster P, Mitschler R R, Elmendorf H G, Haldar K
Department of Microbiology and Immunology, Stanford University School of Medicine, California 94305, USA.
Mol Biochem Parasitol. 1996 Dec 2;83(1):107-20. doi: 10.1016/s0166-6851(96)02759-4.
The rab6 gene product in mammalian cells and yeast is localized to and regulates protein transport in the medial and trans Golgi cisternae, as well as the trans Golgi network. We have identified a homologue in the malaria parasite Plasmodium falciparum which displays a rab-like sequence that is 62.4% identical to mammalian rab6. In addition the parasite gene (Pfrab6 gene) contains an N-terminal hydrophobic domain, unique to P. falciparum. Antibodies developed to Pfrab6 localize protein in 4-7 well-resolved sites in a ring-stage parasite, as detected by high resolution fluorescence microscopy. This suggests that there are multiple, distinct foci of medial/trans Golgi membranes in a ring. ERD2 is a cis Golgi marker in mammalian cells. The plasmodial homologue of ERD2 (PfERD2) is concentrated in a single perinuclear region in a ring-stage parasite. This site is distinct from the Pfrab6 membranes, indicating that early and late Golgi markers can be segregated in P. falciparum. Mammalian cells contain a single Golgi complex where cis medial and trans markers are tightly stacked in closely apposed cisternae. In P. falciparum-rings however, rab6-associated membranes are not invariably 'stacked' with an ERD2 structure. In immunoelectron microscopy studies, both the PfERD2- and Pfrab6-associated membranes appear tubulovesicular in nature, devoid of cisternal morphology. Hence the Golgi of ring stage parasites may comprise of multiple, 'unstacked' tubulovesicular clusters, suggesting a primitive organization of the organelle in Plasmodia.
哺乳动物细胞和酵母中的rab6基因产物定位于高尔基体中间膜囊、反面膜囊以及反式高尔基体网络，并调节其中的蛋白质运输。我们在疟原虫恶性疟原虫中鉴定出了一种同源物，它具有与哺乳动物rab6 62.4%相同的rab样序列。此外，该寄生虫基因（Pfrab6基因）包含一个恶性疟原虫特有的N端疏水结构域。通过高分辨率荧光显微镜检测，针对Pfrab6产生的抗体将蛋白质定位在环状期寄生虫的4 - 7个清晰可辨的位点。这表明环状期存在多个不同的高尔基体中间膜囊/反面膜囊膜聚集点。ERD2是哺乳动物细胞中的顺式高尔基体标志物。ERD2的疟原虫同源物（PfERD2）在环状期寄生虫中集中于单个核周区域。该位点与Pfrab6膜不同，这表明早期和晚期高尔基体标志物在恶性疟原虫中可以分离。哺乳动物细胞含有单个高尔基体复合体，其中顺式、中间和反式标志物紧密堆叠在相邻的膜囊中。然而在恶性疟原虫环状体中，与rab6相关的膜并不总是与ERD2结构“堆叠”在一起。在免疫电子显微镜研究中，与PfERD2和Pfrab6相关的膜在本质上均呈管状小泡状，没有膜囊形态。因此，环状期寄生虫的高尔基体可能由多个“未堆叠”的管状小泡簇组成，这表明疟原虫中该细胞器的组织结构较为原始。
