Valentini S R, Weiss V H, Silver P A
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, and Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA.
RNA. 1999 Feb;5(2):272-80. doi: 10.1017/s1355838299981633.
Hrp1p is a heterogeneous ribonucleoprotein (hnRNP) from the yeast Saccharomyces cerevisiae that is involved in the cleavage and polyadenylation of the 3'-end of mRNAs and mRNA export. In addition, Hrplp is one of several RNA-binding proteins that are posttranslationally modified by methylation at arginine residues. By using functional recombinant Hrp1p, we have identified RNA sequences with specific high affinity binding sites. These sites correspond to the efficiency element for mRNA 3'-end formation, UAUAUA. To examine the effect of methylation on specific RNA binding, purified recombinant arginine methyltransferase (Hmt1p) was used to methylate Hrp1p. Methylated Hrp1p binds with the same affinity to UAUAUA-containing RNAs as unmethylated Hrpl p indicating that methylation does not affect specific RNA binding. However, RNA itself inhibits the methylation of Hrp1p and this inhibition is enhanced by RNAs that specifically bind Hrpl p. Taken together, these data support a model in which protein methylation occurs prior to protein-RNA binding in the nucleus.
Hrp1p是来自酿酒酵母的一种不均一核糖核蛋白（hnRNP），它参与mRNA 3'端的切割和聚腺苷酸化以及mRNA输出。此外，Hrp1p是几种在精氨酸残基处发生甲基化翻译后修饰的RNA结合蛋白之一。通过使用功能性重组Hrp1p，我们鉴定出了具有特定高亲和力结合位点的RNA序列。这些位点对应于mRNA 3'端形成的效率元件UAUAUA。为了研究甲基化对特定RNA结合的影响，使用纯化的重组精氨酸甲基转移酶（Hmt1p）对Hrp1p进行甲基化。甲基化的Hrp1p与含UAUAUA的RNA结合的亲和力与未甲基化的Hrp1p相同，这表明甲基化不影响特定RNA结合。然而，RNA本身会抑制Hrp1p的甲基化，并且这种抑制会被特异性结合Hrp1p的RNA增强。综上所述，这些数据支持了一种模型，即蛋白质甲基化发生在细胞核中蛋白质-RNA结合之前。
