Eckert W A, Kaffenberger W, Krohne G, Franke W W
Eur J Biochem. 1978 Jul 3;87(3):607-16. doi: 10.1111/j.1432-1033.1978.tb12413.x.
The stability of Tetrahymena pyriformis cytoplasmic rRNAs and nuclear rRNA precursors has been studied by polyacrylamide gel electrophoresis under partly and completely denaturing conditions. Cytoplasmic 17-S rRNA (Mr = 0.66 X 10(6) consists of a continuous polynucleotide chain throughout its lifetime, whereas the bulk of 26-S rRNA (Mr = 1.2m X 10(6) dissociates upon denaturation. Two large fragments (F1, F2) of somewhat different molecular weights (Mr 0.63 X 10(6) and 0.58 X 10(6) and the small 5.8-S rRNA fragment (Mr about 50 000) are regularly observed. Some additional distinct minor fragments (F3-F6) are noted under certain preparative conditions, suggestive of artifactual origin. The following conclusions were made from the data obtained . (a) Newly synthesized 26-S rRNA molecules do not contain the 'central' hidden break (separating F1 and F2) until about 15 min after their appearance in the cytoplasm; however, they release during denaturation the 5.8-S and/or a short-lived 7-S fragment (Mr about 75 000) which might represent a direct precursor to the 5.8-S rRNA. (b) The immediate nuclear precursor to the 26-S rRNA (Mr 1.39 X 10(6) releases a small fragment of similar size (7 S). (c) The largest stable transcription product of the rDNA (pre-rRNA) does not contain any hidden break.
通过在部分变性和完全变性条件下的聚丙烯酰胺凝胶电泳，对梨形四膜虫细胞质rRNA和核rRNA前体的稳定性进行了研究。细胞质17-S rRNA（Mr = 0.66×10⁶）在其整个生命周期中由一条连续的多核苷酸链组成，而大部分26-S rRNA（Mr = 1.2m×10⁶）在变性时会解离。经常观察到两个分子量略有不同的大片段（F1、F2）（Mr 0.63×10⁶和0.58×10⁶）以及小的5.8-S rRNA片段（Mr约50000）。在某些制备条件下还注意到一些额外的明显小片段（F3 - F6），提示其人为起源。根据所获得的数据得出了以下结论。（a）新合成的26-S rRNA分子在出现在细胞质中约15分钟后才含有“中心”隐藏断裂（将F1和F2分开）；然而，它们在变性时会释放出5.8-S和/或一个短寿命的7-S片段（Mr约75000），后者可能代表5.8-S rRNA的直接前体。（b）26-S rRNA的直接核前体（Mr 1.39×10⁶）会释放一个大小相似的小片段（7S）。（c）rDNA的最大稳定转录产物（前体rRNA）不包含任何隐藏断裂。
