Schimmang T, Tollervey D, Kern H, Frank R, Hurt E C
EMBL, Heidelberg, FRG.
EMBO J. 1989 Dec 20;8(13):4015-24. doi: 10.1002/j.1460-2075.1989.tb08584.x.
In order to study the structural and functional organization of the eukaryotic nucleolus, we have started to isolate and characterize nucleolar components of the yeast Saccharomyces cerevisiae. We have identified a major 38 kd nucleolar protein (NOP1), which is located within nucleolar structures resembling the dense fibrillar region of mammalian nucleoli. This 38 kd protein is conserved in evolution since affinity-purified antibodies against the yeast protein stain the nucleolus of mammalian cells in indirect immunofluorescence microscopy and the yeast protein is decorated by antibodies directed against human fibrillarin. Affinity-purified antibodies against the yeast NOP1 efficiently precipitate at least seven small nuclear RNAs involved in rRNA maturation. We have cloned the gene encoding the yeast NOP1 protein. Haploid cells carrying a disrupted copy of the gene are not viable, showing that NOP1 is essential for cell growth. The gene codes for a 34.5 kd protein which contains glycine/arginine rich sequence repeats at the amino terminus similar to those found in other nucleolar proteins. This suggests that NOP1 is in association with small nucleolar RNAs, required for rRNA processing and likely to be the homologue of the mammalian fibrillarin.
为了研究真核生物核仁的结构和功能组织，我们已开始分离并鉴定酿酒酵母的核仁成分。我们鉴定出一种主要的38kd核仁蛋白（NOP1），它位于类似于哺乳动物核仁致密纤维区的核仁结构内。这种38kd蛋白在进化过程中是保守的，因为针对酵母蛋白的亲和纯化抗体在间接免疫荧光显微镜下可使哺乳动物细胞核仁染色，并且酵母蛋白可被针对人纤维蛋白原的抗体标记。针对酵母NOP1的亲和纯化抗体可有效沉淀至少七种参与rRNA成熟的小核RNA。我们已克隆了编码酵母NOP1蛋白的基因。携带该基因中断拷贝的单倍体细胞无法存活，这表明NOP1对细胞生长至关重要。该基因编码一种34.5kd的蛋白，其氨基末端含有富含甘氨酸/精氨酸的序列重复，类似于在其他核仁蛋白中发现的序列重复。这表明NOP1与小核仁RNA相关，是rRNA加工所必需的，并且可能是哺乳动物纤维蛋白原的同源物。
