Applied Molecular Bioscience, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan.
Insect Mol Biol. 2010 Jun 1;19(3):291-301. doi: 10.1111/j.1365-2583.2009.00982.x. Epub 2009 Dec 23.
The lipid modifications which occur on Bombyx mori Ras proteins BmRas1, BmRas2 and BmRas3 were studied by metabolic labelling in an insect cell-free protein synthesis system and in a baculovirus expression system, using specific inhibitors of protein prenylation and protein palmitoylation. In addition, the subcellular localization of BmRas proteins was examined using EGFP fusion proteins of constitutively active forms of BmRas proteins transiently expressed in Sf9 cells. As a result, it was revealed that the three B. mori Ras proteins BmRas1, BmRas2 and BmRas3 are neither farnesylated nor palmitoylated but are geranylgeranylated for localization to the plasma membrane of insect cells. Thus, the mechanism of membrane binding of insect Ras proteins is quite different from that reported for mammalian Ras proteins.
我们利用昆虫细胞无细胞蛋白合成系统和杆状病毒表达系统，通过特定的蛋白质异戊烯基化和蛋白质棕榈酰化抑制剂，对家蚕 Ras 蛋白 BmRas1、BmRas2 和 BmRas3 发生的脂质修饰进行了研究。此外，我们还使用瞬时表达于 Sf9 细胞的组成性激活形式的 EGFP 融合蛋白，研究了 BmRas 蛋白的亚细胞定位。结果表明，这三种家蚕 Ras 蛋白 BmRas1、BmRas2 和 BmRas3 既不被法呢基化也不被棕榈酰化，而是被 geranylgeranylated 以定位于昆虫细胞的质膜。因此，昆虫 Ras 蛋白的膜结合机制与已报道的哺乳动物 Ras 蛋白的机制有很大的不同。
