Oda T, Ito A
J Biochem. 1981 May;89(5):1547-54. doi: 10.1093/oxfordjournals.jbchem.a133348.
Nascent peptides on free and bound ribosomes prepared from rat liver were labeled and released with [3H]puromycin, and the amounts of the nascent peptides of two secretory proteins, serum albumin and transferrin, were determined by immunoprecipitation with specific antibodies. An appreciable amount of serum albumin nascent peptides was associated with free ribosomes, although most of them were carried by bound ribosomes. Serum albumin nascent peptides associated with free ribosomes were smaller in size than those carried by bound ribosomes. When the products of cell-free translation programmed by free and bound polysomes were immunoprecipitated with antibodies, the percentages of serum albumin to the total translation products were in good agreement with those obtained in the nascent peptides experiment. Cell-free translation of free polysomes produced serum albumin with a similar molecular weight to the authentic one. Although nascent peptides of transferrin were detected only on bound ribosomes, and not on free ribosomes, the transferrin antibody immunoprecipitated 0.2% of total translation products of free polysomes. These observations indicate that free polysomes have complete messenger RNA's and shorter growing nascent peptides of serum albumin and transferrin.
用[3H]嘌呤霉素标记并释放从大鼠肝脏制备的游离核糖体和结合核糖体上的新生肽，并用特异性抗体通过免疫沉淀法测定两种分泌蛋白血清白蛋白和转铁蛋白的新生肽量。尽管大多数血清白蛋白新生肽由结合核糖体携带，但仍有相当数量的血清白蛋白新生肽与游离核糖体相关。与游离核糖体相关的血清白蛋白新生肽比结合核糖体携带的新生肽尺寸更小。当用抗体对由游离多核糖体和结合多核糖体编程的无细胞翻译产物进行免疫沉淀时，血清白蛋白占总翻译产物的百分比与新生肽实验中获得的结果高度一致。游离多核糖体的无细胞翻译产生的血清白蛋白与天然血清白蛋白分子量相似。尽管仅在结合核糖体上检测到转铁蛋白的新生肽，而在游离核糖体上未检测到，但转铁蛋白抗体免疫沉淀了游离多核糖体总翻译产物的0.2%。这些观察结果表明，游离多核糖体具有完整的信使RNA，以及血清白蛋白和转铁蛋白较短的正在生长的新生肽。
