Zaboĭkin M M, Lichtenstein A V, Shapot V S
Mol Biol (Mosk). 1981 Nov-Dec;15(6):1330-41.
It is shown that the stochastic model of hnRNA decay is inconsistent with a number of experimental data. The model of ordered in time and space movement of nascent and post-transcriptional RNA molecules "on conveyer" coupled with certain processing steps is put forward. Since degradation of the pre-mRNA molecule proceeds not instantaneously but in several subsequent steps, the notion of the "exiton" is introduced. The exiton is proposed to be a submolecular metabolically indivisible fragment of RNA molecule which decays as a unit. From this point of view, a population of nuclear RNAs, as a whole, can be presented (and easily mathematically treated) as a community of exiton transporters of various life spans moving in parallel. The life-time spectrum of exitons in population of rat liver hnRNA was computed. The share of exitons with life-time from 41.5 to 42.5 min appeared to be most in the population. Exitons with life-times above 1 h and 2 h comprise approximately 50 and 20% of the total population, respectively. The consequences of the model proposed are discussed.
研究表明，核内不均一RNA（hnRNA）衰变的随机模型与许多实验数据不一致。提出了新生RNA和转录后RNA分子在“传送带”上进行时空有序移动并伴有特定加工步骤的模型。由于前体信使RNA（pre-mRNA）分子的降解不是瞬间发生的，而是在几个后续步骤中进行的，因此引入了“激子”的概念。激子被认为是RNA分子的亚分子代谢不可分割片段，它作为一个整体衰变。从这个角度来看，核RNA群体作为一个整体，可以被呈现（并且易于进行数学处理）为不同寿命的激子转运体并行移动的群落。计算了大鼠肝脏hnRNA群体中激子的寿命谱。寿命在41.5至42.5分钟之间的激子在群体中所占比例最大。寿命超过1小时和2小时的激子分别约占总数的50%和20%。讨论了所提出模型的后果。
