Transmembrane movement of a water-soluble analogue of mannosylphosphoryldolichol is mediated by an endoplasmic reticulum protein.
Transmembrane movement of a water-soluble analogue of mannosylphosphoryldolichol is mediated by an endoplasmic reticulum protein.
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DOI：
10.1083/jcb.130.3.529
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发表时间：
1995-08
期刊：
影响因子：
--
通讯作者：
Waechter CJ
中科院分区：
文献类型：
--
作者：
Rush JS;Waechter CJ
基于拓扑学研究，甘露糖基磷酰基多萜醇（Man-P-Dol）在RER的细胞质表面上合成，但在甘露糖基-磷酰基头基横向扩散到腔室之后，在Glc 3 Man 9 GlcNAc 2-P-P-多萜醇生物合成中作为甘露糖基供体起作用。甘露糖磷酸香茅醇（Man-P- Cit）是Man-P-Dol的一种水溶性类似物，通过小鼠肝微粒体囊泡的转运，已被研究作为一种潜在的实验方法来确定膜蛋白是否介导Man-P-Dol的跨双层运动。对于这些研究，β-[3 H]Man-P- Cit用来自藤黄微球菌的Man-P-十一肾上腺素合酶的部分纯化制剂酶促合成。发现放射性标记的水溶性类似物的摄取具有（a）时间依赖性;（B）立体选择性;（c）依赖于完整的渗透屏障;（d）可饱和;（e）蛋白酶敏感性;和（f）相对于富含高尔基体复合物的囊泡和完整线粒体，ER富集囊泡中的摄取最高。与膜蛋白的参与一致，类似物没有进入合成的磷脂酰胆碱-脂质体。[3 H]Man-P-Cit也不被人红细胞转运。这些结果表明，Man-P-Cit通过小鼠肝微粒体密封囊泡的转运是由膜蛋白转运系统介导的。可能相同的膜蛋白参与ER中Man-P-Dol的跨双层运动。
Based on topological studies mannosylphosphoryldolichol (Man-P-Dol) is synthesized on the cytoplasmic face of the RER, but functions as a mannosyl donor in Glc3Man9GlcNAc2-P-P-dolichol biosynthesis after the mannosyl-phosphoryl headgroup diffuses transversely to the luminal compartment. The transport of mannosylphosphorylcitronellol (Man-P- Cit), a water-soluble analogue of Man-P-Dol, by microsomal vesicles from mouse liver, has been investigated as a potential experimental approach to determine if a membrane protein(s) mediates the transbilayer movement of Man-P-Dol. For these studies beta-[3H]Man-P- Cit was synthesized enzymatically with a partially purified preparation of Man-P-undecaprenol synthase from Micrococcus luteus. The uptake of the radiolabeled water-soluble analogue was found to be (a) time dependent; (b) stereoselective; (c) dependent on an intact permeability barrier; (d) saturable; (e) protease-sensitive; and (f) highest in ER- enriched vesicles relative to Golgi complex-enriched vesicles and intact mitochondria. Consistent with the involvement of a membrane protein, the analogue did not enter synthetic phosphatidylcholine- liposomes. [3H]Man-P-Cit also was not transported by human erythrocytes. These results indicate that the transport of Man-P-Cit by sealed microsomal vesicles from mouse liver is mediated by a membrane protein transport system. It is possible that the same membrane protein(s) participates in the transbilayer movement of Man-P-Dol in the ER.