Memon A R, Clark G B, Thompson G A
Department of Botany, University of Texas, Austin 78713.
Biochem Biophys Res Commun. 1993 Jun 30;193(3):809-13. doi: 10.1006/bbrc.1993.1697.
The ARF class of low molecular mass GTP-binding proteins, originally detected as cholera toxin-activated ADP-ribosylation factors (ARF) in mammalian cells, is now known to participate in intracellular membrane vesicle trafficking. We identified a GTP-binding protein in pea plumules which resembles ARF in several respects. Like mammalian ARF, the pea protein had an apparent molecular mass of 21 kDa and was distributed mainly (approximately 97%) in the cytosol, with 1% and 1.5% occurring in the Golgi and microsomal fractions, respectively. In comparison, small GTP-binding proteins in the 26-30 kDa range were enriched in membranous fractions. The 21 kDa protein crossreacted strongly with an ARF class I antibody prepared against a mammalian ARF, but did not crossreact with ARF 5 (of class II) antibodies. An anti-Volvox yptl antibody did not show immunoreactivity to the 21 kDa pea protein, although it crossreacted strongly with a 28 kDa pea plumule protein. Our results strongly suggest that the 21 kDa pea protein is an analog of the ARF protein localized in the cytosol of mammalian cells. As far as we are aware, this is the first observation of an ARF protein in plants.
低分子量GTP结合蛋白的ARF类别，最初是在哺乳动物细胞中作为霍乱毒素激活的ADP核糖基化因子（ARF）被检测到的，现在已知其参与细胞内膜泡运输。我们在豌豆胚轴中鉴定出一种GTP结合蛋白，它在几个方面与ARF相似。与哺乳动物ARF一样，豌豆蛋白的表观分子量为21 kDa，主要分布在胞质溶胶中（约97%），分别有1%和1.5%存在于高尔基体和微粒体部分。相比之下，26 - 30 kDa范围内的小GTP结合蛋白在膜部分富集。21 kDa的蛋白与针对哺乳动物ARF制备的ARF I类抗体强烈交叉反应，但不与（II类）ARF 5抗体交叉反应。抗团藻yptl抗体对21 kDa的豌豆蛋白不显示免疫反应性，尽管它与一种28 kDa的豌豆胚轴蛋白强烈交叉反应。我们的结果有力地表明，21 kDa的豌豆蛋白是定位于哺乳动物细胞胞质溶胶中的ARF蛋白的类似物。据我们所知，这是在植物中首次观察到ARF蛋白。
