Zeng Bin, Zhu Guran
Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, 4467 TAMU, College Station, TX 77483, USA.
Biochem Biophys Res Commun. 2006 Jul 28;346(2):591-99. doi: 10.1016/j.bbrc.2006.05.165.
Two distinct oxysterol binding protein (OSBP)-related proteins (ORPs) have been identified from the parasitic protist Cryptosporidium parvum (CpORP1 and CpORP2). The short-type CpOPR1 contains only a ligand binding (LB) domain, while the long-type CpORP2 contains Pleckstrin homology (PH) and LB domains. Lipid-protein overlay assays using recombinant proteins revealed that CpORP1 and CpORP2 could specifically bind to phosphatidic acid (PA), various phosphatidylinositol phosphates (PIPs), and sulfatide, but not to other types of lipids with simple heads. Cholesterol was not a ligand for these two proteins. CpOPR1 was found mainly on the parasitophorous vacuole membrane (PVM), suggesting that CpORP1 is probably involved in the lipid transport across this unique membrane barrier between parasites and host intestinal lumen. Although Cryptosporidium has two ORPs, other apicomplexans including Plasmodium, Toxoplasma, and Eimeria possess only a single long-type ORP, suggesting that this family of proteins may play different roles among apicomplexans.
已从小隐孢子虫（CpORP1和CpORP2）这种寄生原生生物中鉴定出两种不同的氧甾醇结合蛋白（OSBP）相关蛋白（ORP）。短型CpOPR1仅包含一个配体结合（LB）结构域，而长型CpORP2包含普列克底物蛋白同源（PH）结构域和LB结构域。使用重组蛋白进行的脂蛋白覆盖分析表明，CpORP1和CpORP2可以特异性结合磷脂酸（PA）、各种磷脂酰肌醇磷酸（PIP）和硫脂，但不能结合其他具有简单头部的脂质类型。胆固醇不是这两种蛋白的配体。发现CpOPR1主要位于纳虫空泡膜（PVM）上，这表明CpORP1可能参与了寄生虫与宿主肠腔之间这种独特膜屏障的脂质转运。虽然隐孢子虫有两种ORP，但包括疟原虫、弓形虫和艾美耳球虫在内的其他顶复门原虫仅拥有一种单一的长型ORP，这表明该蛋白家族在顶复门原虫中可能发挥不同的作用。
