Schneider P, Ferguson M A, McConville M J, Mehlert A, Homans S W, Bordier C
Institut de Biochimie, Université de Lausanne, Epalinges, Switzerland.
J Biol Chem. 1990 Oct 5;265(28):16955-64.
In common with many other plasma membrane glycoproteins of eukaryotic origin, the promastigote surface protease (PSP) of the protozoan parasite Leishmania contains a glycosyl-phosphatidylinositol (GPI) membrane anchor. The GPI anchor of Leishmania major PSP was purified following proteolysis of the PSP and analyzed by two-dimensional 1H-1H NMR, compositional and methylation linkage analyses, chemical and enzymatic modifications, and amino acid sequencing. From these results, the structure of the GPI-containing peptide was found to be Asp-Gly-Gly-Asn-ethanolamine-PO4-6Man alpha 1-6Man alpha 1-4GlcN alpha 1-6myo-inositol-1-PO4-(1-alkyl-2-acyl-glycerol). The glycan structure is identical to the conserved glycan core regions of the GPI anchor of Trypanosoma brucei variant surface glycoprotein and rat brain Thy-1 antigen, supporting the notion that this portion of GPIs are highly conserved. The phosphatidylinositol moiety of the PSP anchor is unusual, containing a fully saturated, unbranched 1-O-alkyl chain (mainly C24:0) and a mixture of fully saturated unbranched 2-O-acyl chains (C12:0, C14:0, C16:0, and C18:0). This lipid composition differs significantly from those of the GPIs of T. brucei variant surface glycoprotein and mammalian erythrocyte acetylcholinesterase but is similar to that of a family of glycosylated phosphoinositides found uniquely in Leishmania.
与许多其他真核生物来源的质膜糖蛋白一样，原生动物寄生虫利什曼原虫的前鞭毛体表面蛋白酶（PSP）含有糖基磷脂酰肌醇（GPI）膜锚定。在对PSP进行蛋白水解后，纯化了杜氏利什曼原虫PSP的GPI锚定，并通过二维1H-1H NMR、组成和甲基化连接分析、化学和酶促修饰以及氨基酸测序进行了分析。从这些结果中，发现含GPI的肽的结构为天冬氨酸-甘氨酸-甘氨酸-天冬酰胺-乙醇胺-磷酸-6甘露糖α1-6甘露糖α1-4葡糖胺α1-6肌醇-1-磷酸-（1-烷基-2-酰基甘油）。聚糖结构与布氏锥虫可变表面糖蛋白和大鼠脑Thy-1抗原的GPI锚定的保守聚糖核心区域相同，支持了GPI这一部分高度保守的观点。PSP锚定的磷脂酰肌醇部分不同寻常，含有一条完全饱和、无分支的1-O-烷基链（主要是C24:0）和一组完全饱和无分支的2-O-酰基链（C12:0、C14:0、C16:0和C18:0）的混合物。这种脂质组成与布氏锥虫可变表面糖蛋白和哺乳动物红细胞乙酰胆碱酯酶的GPI有显著差异，但与利什曼原虫中独特发现的一类糖基化磷酸肌醇相似。
