GPI1 stabilizes an enzyme essential in the first step of glycosylphosphatidylinositol biosynthesis
GPI1 stabilizes an enzyme essential in the first step of glycosylphosphatidylinositol biosynthesis
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DOI：
10.1074/jbc.274.26.18582
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发表时间：
1999-06-25
影响因子：
4.8
通讯作者：
Kinoshita, T
中科院分区：
文献类型：
--
作者：
Hong, Y;Ohishi, K;Kinoshita, T
糖基磷脂酰肌醇（GPI）的附着对于许多蛋白质的表面表达是必需的。糖基磷脂酰肌醇的生物合成是由N-乙酰葡糖胺从UDP-N-乙酰葡糖胺转移到磷脂酰肌醇开始的。在哺乳动物细胞中，该反应由PIG-A、PIG-H、PIG-C和GPI 1的复合物介导。这种复杂性可能与特定磷脂酰肌醇的调节和使用有关。然而，各组成部分的职能一直不清楚。在这里，我们克隆了小鼠GPI 1基因，并在F9胚胎癌细胞中破坏它。GPI 1基因的破坏导致了糖基磷脂酰肌醇锚定蛋白产生的严重但不完全的缺陷，表明一些残留的生物合成活性。PIG-A、PIG-H和PIG-C的复合物降至几乎检测不到的水平，而PIG-A和PIG-H的复合物很容易检测到。GPI 1的缺乏也导致PIG-C和PIG-H的部分降低。因此，GPI 1通过将PIG-C与PIG-A和PIG-H的复合物结合来稳定酶。
Attachment of glycosylphosphatidylinositol (GPI) is essential for the surface expression of many proteins. Biosynthesis of glycosylphosphatidylinositol is initiated by the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine to phosphatidylinositol. In mammalian cells, this reaction is mediated by a complex of PIG-A, PIG-H, PIG-C, and GPI1. This complexity may be relevant for regulation and for usage of a particular phosphatidylinositol. However, the functions of the respective components have been unclear. Here we cloned the mouse GPI1 gene and disrupted it in F9 embryonal carcinoma cells. Disruption of the GPI1 gene caused a severe but not complete defect in the generation of glycosylphosphatidylinositol-anchored proteins, indicating some residual biosynthetic activity. A complex of PIG-A, PIG-H, and PIG-C decreased to a nearly undetectable level, whereas a complex of PIG-A and PIG-H was easily detected. A lack of GPI1 also caused partial decreases of PIG-C and PIG-H. Therefore, GPI1 stabilizes the enzyme by tying up PIG-C with a complex of PIG-A and PIG-H.