Park J H, Jensen B C, Kifer C T, Parsons M
Seattle Biomedical Research Institute, Seattle, WA 98109, USA.
J Cell Sci. 2001 Jan;114(Pt 1):173-185. doi: 10.1242/jcs.114.1.173.
We describe here a novel, evolutionarily conserved set of predicted G-proteins. The founding member of this family, TbNOG1, was identified in a two-hybrid screen as a protein that interacts with NOPP44/46, a nucleolar phosphoprotein of Trypanosoma brucei. The biological relevance of the interaction was verified by co-localization and co-immunoprecipitation. TbNOG1 localized to the trypanosome nucleolus and interacted with domains of NOPP44/46 that are found in several other nucleolar proteins. Genes encoding proteins highly related to TbNOG1 are present in yeast and metazoa, and related G domains are found in bacteria. We show that NOG1 proteins in humans and Saccharomyces cerevisae are also nucleolar. The S. cerevisae NOG1 gene is essential for cell viability, and mutations in the predicted G motifs abrogate function. Together these data suggest that NOG1 may play an important role in nucleolar functions. The GTP-binding region of TbNOG1 is similar to those of Obg and DRG proteins, which, together with NOG, form a newly recognized family of G-proteins, herein named ODN. The ODN family differs significantly from other G-protein families, and shows several diagnostic sequence characteristics. All organisms appear to possess an ODN gene, pointing to the biological significance of this family of G-proteins.
我们在此描述了一组新的、进化上保守的预测G蛋白。该家族的创始成员TbNOG1是在双杂交筛选中被鉴定为一种与布氏锥虫的核仁磷蛋白NOPP44/46相互作用的蛋白质。通过共定位和共免疫沉淀验证了这种相互作用的生物学相关性。TbNOG1定位于锥虫核仁，并与在其他几种核仁蛋白中发现的NOPP44/46结构域相互作用。编码与TbNOG1高度相关蛋白质的基因存在于酵母和后生动物中，并且在细菌中发现了相关的G结构域。我们表明人类和酿酒酵母中的NOG1蛋白也位于核仁。酿酒酵母的NOG1基因对细胞活力至关重要，并且预测的G基序中的突变会消除功能。这些数据共同表明NOG1可能在核仁功能中起重要作用。TbNOG1的GTP结合区域与Obg和DRG蛋白的相似，它们与NOG一起形成了一个新认识的G蛋白家族，在此命名为ODN。ODN家族与其他G蛋白家族有显著差异，并显示出几个诊断性序列特征。所有生物似乎都拥有一个ODN基因，这表明了这个G蛋白家族的生物学意义。
