Smith S D, Banerjee N, Sitz T O
Biochemistry. 1984 Jul 31;23(16):3648-52. doi: 10.1021/bi00311a011.
Two bands of 5.8S rRNA were observed when the total RNA isolated from rat or mouse tissue was separated by electrophoresis on high-resolution polyacrylamide gels under denaturing conditions. The minor form, with a lower mobility, represented 15-35% of the total 5.8S rRNA, depending on the source of the tissue. Sequence analysis and the kinetics of formation showed that this minor form is elongated at the 5' end and is not a precursor. The sequence of the minor form was found to be p(C)CGAUA[CG-, five or six nucleotides longer than the major form. The minor 5.8S rRNA constituent also formed a more stable junction complex with 28S rRNA than the shorter major sequence. The rat DNA sequence that corresponds to the additional nucleotides at the 5' end of 5.8S rRNA has been reported to be -CCGTACG-[Subrahmanyam, C. S., Cassidy, B., Busch, H., & Rothblum, L. I. (1982) Nucleic Acids Res. 10, 3667-3680], a sequence which does not contain the extra adenylic acid residue at position 4 found in the minor form. This suggests that the rodent rRNA genes are heterogeneous and that the insertion of an A residue in the ribosomal precursor RNA can generate an alternate processing site.
当在变性条件下，将从大鼠或小鼠组织中分离得到的总RNA在高分辨率聚丙烯酰胺凝胶上进行电泳分离时，观察到了两条5.8S rRNA条带。迁移率较低的次要形式占总5.8S rRNA的15%-35%，这取决于组织来源。序列分析和形成动力学表明，这种次要形式在5'端是延长的，并非前体。发现次要形式的序列为p(C)CGAUA[CG-，比主要形式长五或六个核苷酸。与较短的主要序列相比，次要的5.8S rRNA成分与28S rRNA形成的连接复合体也更稳定。据报道，与5.8S rRNA 5'端额外核苷酸相对应的大鼠DNA序列为-CCGTACG-[Subrahmanyam, C. S., Cassidy, B., Busch, H., & Rothblum, L. I. (1982) Nucleic Acids Res. 10, 3667-3680]，该序列在次要形式的第4位不包含额外的腺苷酸残基。这表明啮齿动物的rRNA基因是异质的，并且核糖体前体RNA中A残基的插入可以产生一个替代的加工位点。
