Quinlan T J, Kinniburgh A J, Martin T E
J Biol Chem. 1977 Feb 25;252(4):1156-61.
Ribonucleoprotein (RNP) subcomplexes containing at least 60% of the total nuclear poly(A) were isolated from mouse ascites cells; these 15 S ribonucleoprotein particles were most probably derived from larger hnRNA containing complexes. The buoyant density of the 15 S ribonucleoprotein in formaldehyde-CsCl was significantly less than that of the hnRNA-containing 30 S ribonucleoprotein subcomplex, indicating a higher proportion of protein (approximately 80%) in the 15 S ribonucleoprotein. The proteins partially protected the poly(A) from the action of ribonuclease T2. RNA isolated from purified 15 S ribonucleoprotein was estimated to be 190 to 200 nucleotides in length by gel electrophoresis, whereas the RNA from crude preparations was slightly larger. Base composition analysis of 32P-labeled crude 15 S RNP-RNA showed it to be rich in adenylate (70%) but containing a substantial amount of uridylate (20%). The base composition of RNA from purified complexes was approximately 90% adenyalte. Our results suggested that oligo(U) sequences from hnRNA could artificially associated with the poly(A) during preparation of 15 S RNP-RNA.
从小鼠腹水细胞中分离出了核糖核蛋白（RNP）亚复合物，其含有至少60%的总核聚腺苷酸；这些15S核糖核蛋白颗粒很可能源自更大的含有不均一核RNA（hnRNA）的复合物。在甲醛 - 氯化铯中的15S核糖核蛋白的浮力密度显著低于含有hnRNA的30S核糖核蛋白亚复合物，这表明15S核糖核蛋白中蛋白质的比例更高（约80%）。这些蛋白质部分保护了聚腺苷酸免受核糖核酸酶T2的作用。通过凝胶电泳估计，从纯化的15S核糖核蛋白中分离出的RNA长度为190至200个核苷酸，而粗制品中的RNA略大。对32P标记的粗制15S核糖核蛋白 - RNA的碱基组成分析表明，其富含腺苷酸（70%），但含有大量尿苷酸（20%）。纯化复合物中RNA的碱基组成约为90%腺苷酸。我们的结果表明，在制备15S核糖核蛋白 - RNA的过程中，hnRNA中的寡聚尿苷酸序列可能会与聚腺苷酸人为结合。
