Berger L C, Bag J, Sells B H
Department of Molecular Biology and Genetics, College of Biological Science, University of Guelph, Ont., Canada.
Biochem Cell Biol. 1992 Sep;70(9):770-8. doi: 10.1139/o92-117.
Translational efficiency of a minor group of mRNAs is regulated by serum levels in 3T6 fibroblasts. Included within this group is the poly(A)-binding protein (PABP) mRNA. We analyzed the distribution of PABP mRNA in polysome profiles and found a large percentage of this mRNA to be translationally repressed in both actively growing (approximately 60%) and resting cells (approximately 70%). Elevated serum levels induced a distinct bimodal distribution of this mRNA between actively translated and repressed fractions. Similarly, treatment of cells with low doses of cycloheximide also generated a partial shift of repressed PABP mRNA into the actively translated fraction. In an attempt to characterize the factors which regulate PABP mRNA translation we have identified the proteins which bind to this mRNA in vitro. Sequences within the 5' untranslated region were found to be sufficient for binding of all proteins to this mRNA. We suggest that this region and the proteins associated with it may be essential for translation control of PABP mRNA.
一小部分mRNA的翻译效率受3T6成纤维细胞中血清水平的调控。该组mRNA中包括聚腺苷酸结合蛋白（PABP）mRNA。我们分析了PABP mRNA在多核糖体图谱中的分布，发现该mRNA的很大一部分在活跃生长的细胞（约60%）和静止细胞（约70%）中均受到翻译抑制。血清水平升高导致该mRNA在活跃翻译部分和抑制部分之间呈现明显的双峰分布。同样，用低剂量环己酰亚胺处理细胞也会使受抑制的PABP mRNA部分转移到活跃翻译部分。为了确定调控PABP mRNA翻译的因素，我们鉴定了在体外与该mRNA结合的蛋白质。发现5'非翻译区内的序列足以使所有蛋白质与该mRNA结合。我们认为该区域及其相关蛋白质可能对PABP mRNA的翻译控制至关重要。
