Elmendorf H G, Haldar K
Department of Microbiology and Immunology, Stanford University School of Medicine 94305-5402.
EMBO J. 1993 Dec;12(12):4763-73. doi: 10.1002/j.1460-2075.1993.tb06165.x.
The ERD2 gene product in mammalian cells and yeast is a receptor required for protein retention in the endoplasmic reticulum (ER); immunolocalization studies indicate that the protein is concentrated in the cis Golgi. We have identified a homologue of ERD2 in the malaria parasite, Plasmodium falciparum (PfERD2). The deduced protein sequence is 42% identical to mammalian and yeast homologues and bears striking homology in its proposed tertiary structure. PfERD2 is tightly confined to a single focus of staining in the perinuclear region as seen by indirect immunofluorescence. This is redistributed by brefeldin A (BFA) to a diffuse pattern similar to that of parasite BiP, a marker for the ER; removal of the drug results in recovery of the single focus, consistent with the localization of PfERD2 to the parasite Golgi and its participation in a retrograde transport pathway to the ER. Sphingomyelin synthesis is a second resident activity of the cis Golgi whose organization is sensitive to BFA in mammalian cells. Within the parasite it again localizes to a perinuclear region but does not reorganize upon BFA treatment. The results strongly suggest that these two activities are in distinct compartments of the Golgi in the malaria parasite.
哺乳动物细胞和酵母中的ERD2基因产物是内质网（ER）中蛋白质滞留所需的一种受体；免疫定位研究表明该蛋白质集中在顺式高尔基体中。我们在疟原虫恶性疟原虫（PfERD2）中鉴定出了ERD2的一个同源物。推导的蛋白质序列与哺乳动物和酵母的同源物有42%的同一性，并且在其推测的三级结构上具有显著的同源性。如间接免疫荧光所示，PfERD2紧密局限于核周区域的单个染色焦点。用布雷菲德菌素A（BFA）处理后，其重新分布为与寄生虫BiP（一种内质网标记物）类似的弥散模式；去除该药物后，单个焦点恢复，这与PfERD2定位于寄生虫高尔基体及其参与向内质网的逆行转运途径一致。鞘磷脂合成是顺式高尔基体的第二种驻留活性，其在哺乳动物细胞中的组织对BFA敏感。在寄生虫中，它同样定位于核周区域，但经BFA处理后不会重新组织。结果强烈表明，这两种活性存在于疟原虫高尔基体的不同区室中。
