Jefferies H B, Thomas G, Thomas G
Friedrich Miescher-Institut, Basel, Switzerland.
J Biol Chem. 1994 Feb 11;269(6):4367-72.
Stimulation of quiescent Swiss 3T3 cells to proliferate leads to a selective 6-fold increase in the rate of translation of protein synthesis elongation factor eEF-1 alpha. Northern blot and solution hybridization protection studies show that levels of eEF-1 alpha mRNA remain constant following serum stimulation, demonstrating that eEF-1 alpha transcripts are not degraded following mitogenic stimulation and that the increase in eEF-1 alpha synthesis is accounted for by pre-existing mRNA. Localization of these transcripts in resting cells shows that they are largely distributed equally between stored mRNA protein particles and monosomes/disomes. Following serum addition, eEF-1 alpha transcripts present in mRNA protein particles redistribute to large polysomes rather than to monosomes and disomes as would be expected. The same is true for those transcripts present in monosomes and disomes. Salt-shift and translational runoff studies indicate that eEF-1 alpha transcripts sedimenting with monosomes and disomes in quiescent cells are associated with actively translating ribosomes. The results suggest that a specific transcript can move within polysome profile as a function of the affinity of translational apparatus for that transcript.
刺激静止的瑞士3T3细胞增殖会导致蛋白质合成延伸因子eEF-1α的翻译速率选择性地增加6倍。Northern印迹和溶液杂交保护研究表明，血清刺激后eEF-1α mRNA的水平保持恒定，这表明有丝分裂原刺激后eEF-1α转录本不会降解，且eEF-1α合成的增加是由预先存在的mRNA所致。这些转录本在静止细胞中的定位表明，它们在很大程度上均匀分布于储存的mRNA蛋白颗粒与单体/二聚体之间。血清添加后，mRNA蛋白颗粒中存在的eEF-1α转录本会重新分布到大型多聚核糖体，而不是如预期那样分布到单体和二聚体。单体和二聚体中存在的那些转录本也是如此。盐析和翻译延伸研究表明，在静止细胞中与单体和二聚体一起沉降的eEF-1α转录本与正在进行翻译的核糖体相关。结果表明，特定的转录本可根据翻译装置对该转录本的亲和力在多聚核糖体图谱内移动。
