The fatty acids in unremodelled trypanosome glycosyl-phosphatidylinositols.
The fatty acids in unremodelled trypanosome glycosyl-phosphatidylinositols.
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未重构锥虫糖基磷脂酰肌醇中的脂肪酸。
DOI：
10.1042/bj2990741
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Englund,PT
中科院分区：
文献类型：
--
作者：
Doering,TL;Pessin,MS;Hart,GW;Raben,DM;Englund,PT
糖脂A是锥虫变异体表面糖蛋白的糖基-磷脂酰肌醇（GPI）锚的前体，分两个阶段构建。首先，聚糖在磷脂酰肌醇（PI）上组装，产生称为A '的糖脂。其次，糖脂A'通过脱酰和再酰化经历脂肪酸重塑，成为二肉豆蔻酰种类的糖脂A。在本文中，我们研究了糖脂A'及其细胞祖细胞的脂肪酸含量。A'仅含有在sn-1位的硬脂酸酯和在sn-2位的脂肪酸的复杂混合物（包括18：0、18：1、18：2、20：4和22：6）。据推测，这些脂肪酸来源于最初进入生物合成途径的含硬脂酸盐的PI物质。我们比较了来自糖脂A'的二酰基甘油种类与来自磷脂酰肌醇的二酰基甘油种类，以确定含硬脂酸盐的PI的子集是否用于GPI生物合成。我们发现PI中含硬脂酸酯的二酰基甘油的光谱与A '中的相似，尽管每种化合物的比例不同。总PI通常在含硬脂酸盐物质中高度富集。糖基化PI和总细胞PI之间的组成差异可能是由于启动GPI生物合成途径的糖转移酶的底物特异性。或者，存在于GPI生物合成的内质网位点处的PI的种类可能不同于总PI中的那些。
Glycolipid A, the precursor of the glycosyl-phosphatidylinositol (GPI) anchor of the trypanosome variant surface glycoprotein, is constructed in two phases. First, the glycan is assembled on phosphatidylinositol (PI), yielding a glycolipid termed A'. Second, glycolipid A' undergoes fatty acid remodelling, by deacylation and reacylation, to become the dimyristoyl species glycolipid A. In this paper, we examine the fatty acid content of glycolipid A' and its cellular progenitors. A' contains exclusively stearate at the sn-1 position and a complex mixture of fatty acids (including 18:0, 18:1, 18:2, 20:4 and 22:6) at sn-2. Presumably these fatty acids derive from stearate-containing PI species which initially enter the biosynthetic pathway. We compared the diacylglycerol species from glycolipid A' with those from phosphatidylinositol to determine whether a subset of stearate-containing PIs is utilized for GPI biosynthesis. We found that the spectrum of stearate-containing diacylglycerols in PI is similar to that in A', although the proportions of each compound differ. Total PI in general was highly enriched in stearate-containing species. Differences in composition between glycosylated PI and total cellular PI may be due to the substrate specificity of the sugar transferase which initiates the GPI biosynthetic pathway. Alternatively, the species of PI present at the endoplasmic reticulum site of GPI biosynthesis may differ from those in total PI.