The metabolism of poly(A)+ and poly(A)− hnRNA in cultured drosophila cells studied with a rapid uridine pulse-chase
The metabolism of poly(A)+ and poly(A)− hnRNA in cultured drosophila cells studied with a rapid uridine pulse-chase
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通过快速尿苷脉冲追踪研究培养果蝇细胞中多聚 (A)+ 和多聚 (A)− hnRNA 的代谢
DOI：
10.1016/0092-8674(77)90321-x
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发表时间：
1977
期刊：
影响因子：
64.5
通讯作者：
S. Penman
中科院分区：
文献类型：
--
作者：
R. Levis;S. Penman
当培养的果蝇细胞用葡萄糖胺预处理并暴露于含有放射性尿嘧啶的脉冲中时，它们的标记几乎可以通过添加未标记的尿嘧啶而立即停止。利用这种脉冲追踪技术，我们研究了hnRNA的衰变和mRNA的形成。聚(A)+和聚(A)- hnrna表现为不同的群体。聚(A) hnRNA占脉冲标记材料的80%，其衰变的初始半衰期为10 -15分钟。聚(A)+分子表现为两种动力学组分，半衰期分别为20和180分钟。果蝇hnRNA的大小分布在hnRNA快速衰减和细胞质mRNA输出的初始阶段没有变化。这表明，这些分子的加工过程一旦开始，就会迅速进行并完成。大部分标记的poly (A)+细胞质mRNA在追逐的前30分钟出现，占总hnRNA放射性损失的14%。我们估计大约40%的脉冲标记核转录本产生细胞质信息分子。细胞核RNA的聚腺苷化必须在追逐过程中继续进行，以解释在细胞质中出现的聚(A)+ mRNA。实际上，先前合成的hnRNA不会形成mRNA，然而，如果正在进行的合成被添加放线菌素d打断，则在给药后，hnRNA的衰变显示出许多异常特征。
When cultured Drosophila cells are pretreated with glucosamine and exposed to a pulse of incorporation of radioactive uridine, their labeling can be halted almost instantaneously by the addition of unlabeled uridine. Using this pulse-chase technique, we have investigated the decay of hnRNA and the formation of mRNA. The poly (A)+ and poly (A)- hnRNAs behave as different populations. The poly (A)) hnRNA constitutes 80% of the pulse-labeled material and decays with an initial half-life of lo-15 min. The poly (A)+ molecules behave as two kinetic components, with half-lives of 20 and 180 min. The size distribution of Drosophila hnRNA does not change during the initial period of rapid hnRNA decay and cytoplasmic mRNA export. This suggests that processing of these molecules, once it has begun, proceeds rapidly and to completion. The bulk of labeled poly (A)+ cytoplasmic mRNA appears during the first 30 min of the chase and amounts to 14% of the loss of radioactivity from total hnRNA. We estimate that on the order of 40% of pulse-labeled nuclear transcripts give rise to a cytoplasmic message molecule. Polyadenylation of nuclear RNA must continue during the chase to account for the poly (A)+ mRNA appearing in the cytoplasm. Virtually no mRNA is formed from previously synthesized hnRNA, however, if ongoing synthesis is interrupted by the addition of actinomycin D. Decay of the hnRNA displays a number of aberrant characteristics after administration of the drug.