Mayrand S, Setyono B, Greenberg J R, Pederson T
J Cell Biol. 1981 Aug;90(2):380-4. doi: 10.1083/jcb.90.2.380.
The processing of heterogeneous nuclear RNA into messenger RNA takes place in special nuclear ribonucleoprotein particles known as hnRNP. We report here the identification of proteins tightly complexed with poly(A)+ hnRNA in intact HeLa cells, as revealed by a novel in situ RNA-protein cross-linking technique. The set of cross-linked proteins includes the A, B, and C "core" hnRNP proteins, as well as the greater than 42,000 mol wt species previously identified in noncross-linked hnRNP. These proteins are shown to be cross-linked by virtue of remaining bound to the poly(A)+ hnRNA in the presence of 0.5% sodium dodecyl sulfate, 0.5 M NaCl, and 60% formamide, during subsequent oligo(dT)-cellulose chromatography, and in isopycnic banding in Cs2SO4 density gradients. These results establish that poly(A)+ hnRNA is in direct contact with a moderately complex set of nuclear proteins in vivo. This not only eliminates earlier models of hnRNP structure that were based upon the concept of a single protein component but also suggests that these proteins actively participate in modulating hnRNA structure and processing in the cell.
异质核RNA加工成信使RNA的过程发生在称为hnRNP的特殊核核糖核蛋白颗粒中。我们在此报告通过一种新的原位RNA-蛋白质交联技术揭示的完整HeLa细胞中与聚腺苷酸（poly(A)）+ hnRNA紧密结合的蛋白质的鉴定结果。交联蛋白组包括A、B和C“核心”hnRNP蛋白，以及先前在非交联hnRNP中鉴定出的分子量大于42,000道尔顿的物种。这些蛋白质在后续的寡聚（dT）-纤维素色谱过程中，以及在硫酸铯（Cs2SO4）密度梯度中的等密度沉降过程中，在存在0.5%十二烷基硫酸钠、0.5 M氯化钠和60%甲酰胺的情况下，由于仍与聚腺苷酸（poly(A)）+ hnRNA结合而被交联。这些结果表明，聚腺苷酸（poly(A)）+ hnRNA在体内与一组中等复杂的核蛋白直接接触。这不仅排除了基于单一蛋白质成分概念的早期hnRNP结构模型，还表明这些蛋白质积极参与调节细胞中hnRNA的结构和加工。
