Berger S L, Cooper H L
Proc Natl Acad Sci U S A. 1975 Oct;72(10):3873-7. doi: 10.1073/pnas.72.10.3873.
The kinetics of degradation of newly synthesized cytoplasmic poly(A)-bearing RNA have been examined in resting human lymphocytes. Two classes were identified, a very labile component with a half-life of less than 17 min and a stable component which remains apparently undiminished during 24 hr of observation. Both classes have molecular weights between 2.5 and 3.5 x 10(5) but the stable material has a narrower size distribution and a slightly lower average molecular weight than the short-lived component. The fate of stable RNA synthesized in the resting cell was also examined after growth stimulation with phytohemagglutinin after 2 and 6 hr of treatment. No transfer of stable material into the labile pool could be discerned; the amount of stable material remained constant. The existence of two species of mRNAs with different lifetimes in animal cells provides a potential means for regulation of protein synthesis by controlling the supply of specific messages. Furthermore, such a short-lived mRNA species may explain the observed disparity between the amount of poly(A)-bearing heterogeneous RNA produced in the nucleus and the amount of mature message found in the cytoplasm.
已对静息人淋巴细胞中新合成的含胞质多聚腺苷酸（poly(A)）的RNA的降解动力学进行了研究。鉴定出两类：一类非常不稳定，半衰期小于17分钟；另一类稳定，在24小时的观察期内含量明显未减少。两类RNA的分子量均在2.5至3.5×10⁵之间，但稳定物质的大小分布更窄，平均分子量略低于短寿命组分。在用植物血凝素刺激生长2小时和6小时后，也检测了静息细胞中合成的稳定RNA的命运。未发现稳定物质转移到不稳定池中；稳定物质的量保持不变。动物细胞中存在两种寿命不同的mRNA，这为通过控制特定信息的供应来调节蛋白质合成提供了一种潜在手段。此外，这种短寿命的mRNA种类可能解释了在细胞核中产生的含多聚腺苷酸的异质RNA量与在细胞质中发现的成熟信息RNA量之间观察到的差异。
