PIG-V involved in transferring the second mannose in glycosylphosphatidylinositol
PIG-V involved in transferring the second mannose in glycosylphosphatidylinositol
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DOI：
10.1074/jbc.m413867200
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发表时间：
2005-03-11
影响因子：
4.8
通讯作者：
Kinoshita, T
中科院分区：
文献类型：
--
作者：
Kang, JY;Hong, YJ;Kinoshita, T
糖基磷脂酰肌醇（GPI）是将许多蛋白质锚定到真核细胞表面的糖脂。GPI的生物合成途径是通过将糖和其他组分依次添加到磷脂酰肌醇来介导的。GPI中的四个甘露糖是从多萜醇-磷酸-甘露糖（Dol-PMan）转移的，并且通过不同的糖苷键连接。因此，产生GPI需要四种Dol-P-Man依赖性甘露糖基转移酶，分别用于第一、第二、第三和第四甘露糖的GPI-MT-I、-MT-II、-MT-III和-MT-IV。GPI-MT-I（PIG-M）、GPI-MT-III（PIG-B）和GPI-MT-IV（SMP 3）先前已报道，但GPI-MT-II仍有待鉴定。在这里，我们报告的克隆PIG-V参与转移第二甘露糖在GPI锚。人PIG-V编码493个氨基酸的内质网（ER）驻留蛋白，具有8个推定的跨膜区。酿酒酵母（Saccharomycescerevisiae）的gpi 18蛋白位于开放阅读框架YBR 004 c中，与人PIG-V的氨基酸序列同源性为25%。PIG-V具有两个面向ER腔的功能重要的保守区域。综上所述，我们认为PIG-V是GPI锚生物合成中的第二个甘露糖基转移酶。
Glycosylphosphatidylinositol (GPI) is a glycolipid that anchors many proteins to the eukaryotic cell surface. The biosynthetic pathway of GPI is mediated by sequential additions of sugars and other components to phosphatidylinositol. Four mannoses in the GPI are transferred from dolichol-phosphate-mannose (Dol-PMan) and are linked through different glycosidic linkages. Therefore, four Dol-P-Man-dependent mannosyl-transferases, GPI-MT-I, -MT-II, -MT-III, and -MT-IV for the first, second, third, and fourth mannoses, respectively, are required for generation of GPI. GPI-MT-I (PIG-M), GPI-MT-III (PIG-B), and GPI-MT-IV (SMP3) were previously reported, but GPI-MT-II remains to be identified. Here we report the cloning of PIG-V involved in transferring the second mannose in the GPI anchor. Human PIG-V encodes a 493-amino acid, endoplasmic reticulum (ER) resident protein with eight putative transmembrane regions. Saccharomyces cerevisiae protein encoded in open reading frame YBR004c, which we termed GPI18, has 25% amino acid identity to human PIG-V. Viability of the yeast gpi18 deletion mutant was restored by human PIG-V cDNA. PIG-V has two functionally important conserved regions facing the ER lumen. Taken together, we suggest that PIG-V is the second mannosyltransferase in GPI anchor biosynthesis.