Auger-Buendia M A, Longuet M, Tavitian A
Biochim Biophys Acta. 1979 Jun 20;563(1):113-28. doi: 10.1016/0005-2787(79)90012-1.
Proteins were isolated from 80-S preribosomal particles and ribosomal subunits of murine L5178Y cells after short and longer periods of incubation with tritiated amino acids. The labeling patterns of ribosomal proteins were compared by two-dimensional polyacrylamide gel electrophoresis. The analysis of isotopic ratios in individual protein spots showed marked differences in the relative kinetics of protein appearance within nucleolar peribosomes and cytoplasmic subunits. Among the about 60 distinct proteins characterized in 80-S preribosomes, 9 ribosomal proteins appeared to incorporate radioactive amino acids more rapidly. These proteins become labeled gradually in the cytoplasmic ribosomal subunits. It was found that one non-ribosomal protein associated with 80-S preribosomes takes up label far more quickly than other preribosomal polypeptides. It is suggested that this set of proteins could associate early with newly transcribed pre-rRNA, more rapidly than others after their synthesis on polyribosomes, and could therefore play a role in the regulation of ribosome synthesis. In isolated 60-S and 40-S ribosomal subunits, we detected five proteins from the large subunit and four proteins from the small subunit which incorporate tritiated amino acids more quickly than the remainder. These proteins were shown to be absent or very faintly labeled in 80-S preribosomal particles, and would associate with ribosomal particles at later stages of the maturation process.
用氚标记的氨基酸对小鼠L5178Y细胞进行短期和长期孵育后，从80-S前核糖体颗粒和核糖体亚基中分离蛋白质。通过二维聚丙烯酰胺凝胶电泳比较核糖体蛋白的标记模式。对单个蛋白质斑点中同位素比率的分析表明，核仁周核糖体和细胞质亚基中蛋白质出现的相对动力学存在显著差异。在80-S前核糖体中鉴定出的约60种不同蛋白质中，有9种核糖体蛋白似乎能更快地掺入放射性氨基酸。这些蛋白质在细胞质核糖体亚基中逐渐被标记。发现一种与80-S前核糖体相关的非核糖体蛋白比其他前核糖体多肽摄取标记的速度要快得多。有人提出，这组蛋白质可能比其他蛋白质在多核糖体上合成后更早地与新转录的前体rRNA结合，因此可能在核糖体合成的调控中发挥作用。在分离的60-S和40-S核糖体亚基中，我们检测到来自大亚基的5种蛋白质和来自小亚基的4种蛋白质，它们掺入氚标记氨基酸的速度比其余蛋白质更快。这些蛋白质在80-S前核糖体颗粒中不存在或标记非常微弱，并且会在成熟过程的后期与核糖体颗粒结合。
