Beachy R N, Thompson J F, Madison J T
United States Plant, Soil and Nutrition Laboratory, Agricultural Research Service, United States Department of Agriculture, Ithaca, New York 14853.
Plant Physiol. 1978 Feb;61(2):139-44. doi: 10.1104/pp.61.2.139.
Polyribosome preparations containing low proportions of monosomes to polyribosomes have been isolated from developing seeds of Glycine max L. Merrill using a high pH-high KCl buffer. The polyribosomes were functional in in vitro protein synthesis reactions using wheat germ 23,000g supernatant preparations. Results of experiments using aurintricarboxylic acid indicated that most or all of the amino acid incorporation in vitro resulted from the completion of nascent polypeptides associated with the isolated polyribosmes. RNA purified from polyribosome preparations by affinity chromatography on oligo(dT)-cellulose was also active in vitro, and had different Mg and K requirements for translation than did the polyribosomes. Translation of oligo(dT)-cellulose-purified mRNA was inhibited by the addition of 7-methylguanosine 5'-phosphate, suggesting that soybean mRNAs are "capped" at their 5' ends. Some, but not all, of the products of these reactions were identical in electrophoretic mobility to radioactive polypeptides of storage proteins produced in soybean cotyledons grown in culture.
使用高pH-高KCl缓冲液从大豆（Glycine max L. Merrill）发育中的种子中分离出了单核糖体与多核糖体比例较低的多核糖体制剂。这些多核糖体在使用小麦胚芽23,000g上清液制剂的体外蛋白质合成反应中具有功能。使用金精三羧酸的实验结果表明，体外大多数或所有氨基酸掺入是由与分离的多核糖体相关的新生多肽的完成所致。通过在寡聚（dT）-纤维素上进行亲和层析从多核糖体制剂中纯化的RNA在体外也具有活性，并且与多核糖体相比，其翻译所需的镁和钾条件不同。添加7-甲基鸟苷5'-磷酸可抑制寡聚（dT）-纤维素纯化的mRNA的翻译，这表明大豆mRNA在其5'末端被“加帽”。这些反应的一些（但不是全部）产物在电泳迁移率上与在培养中生长的大豆子叶中产生的储存蛋白的放射性多肽相同。
