Singh N, Zoeller R A, Tykocinski M L, Lazarow P B, Tartakoff A M
Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106.
Mol Cell Biol. 1994 Jan;14(1):21-31. doi: 10.1128/mcb.14.1.21-31.1994.
A single metabolic path leading to synthesis of ether lipids is known in animal cells, the major products of which are plasmalogens. To learn whether this peroxisomal path is also responsible for the synthesis of base-resistant lipid components of glycosylphosphoinositol (GPI)-anchored membrane proteins, we have investigated the structure of anchor precursor mannolipids both in wild-type cells (CHO-K1 and a macrophage-like line, RAW 264.7) and in two corresponding mutant cells in which ether lipid biosynthesis is severely impaired. We observe that the precursor mannolipids of both the wild-type and mutant cells do not include alkylglycerol. Nevertheless, both wild-type and mutant cells express cell surface GPI-anchored placental alkaline phosphatase (AP) which includes alkali-resistant hydrophobic chains in its anchor moiety. Thus, (i) in normal AP GPI anchor synthesis, any ether-linked substituents must be added either immediately before, during, or after anchor addition to AP, and (ii) the classical peroxisomal path for ether lipid synthesis appears not to contribute to the synthesis of GPI anchors.
动物细胞中已知一条通向醚脂合成的单一代谢途径，其主要产物是缩醛磷脂。为了了解这条过氧化物酶体途径是否也负责糖基磷脂酰肌醇（GPI）锚定膜蛋白的耐碱脂质成分的合成，我们研究了野生型细胞（CHO-K1和巨噬细胞样细胞系RAW 264.7）以及醚脂生物合成严重受损的两种相应突变细胞中锚定前体甘露糖脂的结构。我们观察到，野生型和突变型细胞的前体甘露糖脂都不包括烷基甘油。然而，野生型和突变型细胞都表达细胞表面GPI锚定的胎盘碱性磷酸酶（AP），其锚定部分包含耐碱疏水链。因此，（i）在正常的AP GPI锚定合成中，任何醚键连接的取代基必须在AP锚定添加之前、期间或之后立即添加，并且（ii）经典的过氧化物酶体醚脂合成途径似乎对GPI锚定的合成没有贡献。
