Karwan R, Bennett J L, Clayton D A
Department of Developmental Biology, Stanford University School of Medicine, California 94305-5427.
Genes Dev. 1991 Jul;5(7):1264-76. doi: 10.1101/gad.5.7.1264.
RNase MRP is a site-specific endoribonuclease that processes primer RNA from the leading-strand origin of mammalian mitochondrial DNA replication. It is present in active form as isolated from the nucleus, suggesting a bipartite cellular location and function. The relatively high abundance of nucleus-localized RNase MRP has permitted its purification to near homogeneity and, in turn, has led to the identification of protein components of this ribonucleoprotein. Analysis of the mode of RNA cleavage by nuclear RNase MRP revealed the surprising and unprecedented ability of the endonuclease to process RNA at multiple discrete locations. Substrate cleavage is dependent on the presence of a previously described G-rich sequence element adjacent to the primary site of RNA processing. Downstream cleavage occur in a distance- and sequence-specific manner.
核糖核酸酶MRP是一种位点特异性内切核糖核酸酶，可从哺乳动物线粒体DNA复制的前导链起点加工引物RNA。它以从细胞核中分离出来的活性形式存在，这表明其在细胞中的定位和功能具有双重性。细胞核定位的核糖核酸酶MRP相对丰度较高，这使得它能够被纯化至接近同质，进而导致了这种核糖核蛋白的蛋白质成分的鉴定。对细胞核核糖核酸酶MRP的RNA切割模式的分析揭示了这种内切核酸酶在多个离散位置加工RNA的惊人且前所未有的能力。底物切割依赖于与RNA加工主要位点相邻的先前描述的富含G的序列元件的存在。下游切割以距离和序列特异性方式发生。
