Lee F J, Huang C F, Yu W L, Buu L M, Lin C Y, Huang M C, Moss J, Vaughan M
Institute of Molecular Medicine, School of Medicine, National Taiwan University, Taipei, Taiwan, Republic of China.
J Biol Chem. 1997 Dec 5;272(49):30998-1005. doi: 10.1074/jbc.272.49.30998.
ADP-ribosylation factors (ARFs) are highly conserved approximately 20-kDa guanine nucleotide-binding proteins that enhance the ADP-ribosyltransferase activity of cholera toxin and are believed to participate in vesicular transport in both exocytic and endocytic pathways. Several ARF-like proteins (ARLs) have been cloned from Drosophila, rat, and human; however, the biological functions of ARLs are unknown. We have identified a yeast gene (ARL1) encoding a protein that is structurally related (>60% identical) to human, rat, and Drosophila ARL1. Biochemical analyses of purified recombinant yeast ARL1 (yARL1) protein revealed properties similar to those ARF and ARL1 proteins, including the ability to bind and hydrolyze GTP. Like other ARLs, recombinant yARL1 protein did not stimulate cholera toxin-catalyzed auto-ADP-ribosylation. yARL1 was not recognized by antibodies against mammalian ARLs or yeast ARFs. Anti-yARL1 antibodies did not cross-react with yeast ARFs, but did react with human ARLs. On subcellular fractionation, yARL1, similar to yARF1, was localized to the soluble fraction. The amino terminus of yARL1, like that of ARF, was myristoylated. Unlike Drosophila Arl1, yeast ARL1 was not essential for cell viability. Like rat ARL1, yARL1 might be associated in part with the Golgi complex. However, yARL1 was not required for endoplasmic reticulum-to-Golgi protein transport, and it may offer an opportunity to define an ARL function in another kind of vesicular trafficking, such as the regulated secretory pathway.
ADP-核糖基化因子（ARFs）是高度保守的、分子量约为20 kDa的鸟嘌呤核苷酸结合蛋白，可增强霍乱毒素的ADP-核糖基转移酶活性，并且被认为参与胞吐和胞吞途径中的囊泡运输。已经从果蝇、大鼠和人类中克隆出了几种ARF样蛋白（ARLs）；然而，ARLs的生物学功能尚不清楚。我们鉴定出了一个酵母基因（ARL1），其编码的蛋白在结构上与人、大鼠和果蝇的ARL1相关（>6%相同）。对纯化的重组酵母ARL1（yARL1）蛋白进行的生化分析揭示了其与ARF和ARL1蛋白相似的特性，包括结合和水解GTP的能力。与其他ARLs一样，重组yARL1蛋白不会刺激霍乱毒素催化的自身ADP-核糖基化。抗哺乳动物ARLs或酵母ARFs的抗体无法识别yARL1。抗yARL1抗体不会与酵母ARFs发生交叉反应，但会与人ARLs发生反应。在亚细胞分级分离中，与yARF1相似，yARL1定位于可溶性部分。与ARF一样，yARL1的氨基末端也被肉豆蔻酰化。与果蝇的Arl1不同，酵母ARL1对细胞活力不是必需的。与大鼠的ARL1一样，yARL1可能部分与高尔基体复合体相关。然而，内质网到高尔基体的蛋白质运输并不需要yARL1，它可能为定义ARL在另一种囊泡运输（如调节性分泌途径）中的功能提供了一个机会。
