O'Brien C A, Wolin S L
Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06510.
Genes Dev. 1994 Dec 1;8(23):2891-903. doi: 10.1101/gad.8.23.2891.
The Ro autoantigen is a 60-kD protein that is usually found in small cytoplasmic RNA-protein complexes known as Ro RNPs. Although the Ro RNPs are abundant and conserved components of a variety of vertebrate and invertebrate cells, their function is unknown. We have discovered that the Ro protein is also found complexed with certain variant 5S rRNAs in Xenopus oocytes. These RNAs contain one or more point mutations compared with the major oocyte 5S rRNA sequence as well as additional nucleotides at the 3' end. We demonstrate that the Ro protein binds specifically mutant 5S rRNAs containing 3' terminal extensions. These mutant RNAs are processed inefficiently to mature 5S rRNA and most eventually are degraded. The observation that the Ro autoantigen specifically associates with defective 5S rRNA precursors suggests that this protein may function as part of a novel quality control or discard pathway for 5S rRNA production.
Ro自身抗原是一种60kD的蛋白质，通常存在于称为Ro核糖核蛋白颗粒（Ro RNPs）的小细胞质RNA-蛋白质复合物中。尽管Ro RNPs是各种脊椎动物和无脊椎动物细胞中丰富且保守的成分，但其功能尚不清楚。我们发现，在非洲爪蟾卵母细胞中，Ro蛋白还与某些变异的5S核糖体RNA（rRNA）形成复合物。与主要的卵母细胞5S rRNA序列相比，这些RNA含有一个或多个点突变，并且在3'末端还有额外的核苷酸。我们证明，Ro蛋白特异性结合含有3'末端延伸的突变型5S rRNA。这些突变RNA向成熟5S rRNA的加工效率低下，大多数最终被降解。Ro自身抗原与有缺陷的5S rRNA前体特异性结合这一观察结果表明，该蛋白可能作为5S rRNA产生的新型质量控制或清除途径的一部分发挥作用。
