Greene F C
United States Department of Agriculture, Food Proteins Research Unit, Western Regional Research Center, Science and Education Administration-Agricultural Research, Berkeley, California 94710.
Plant Physiol. 1981 Sep;68(3):778-83. doi: 10.1104/pp.68.3.778.
Free and membrane-associated polysomes were isolated in approximately equal amounts from endosperm of wheat kernels harvested 20 days after anthesis. The presence of heparin in the homogenizing buffer minimized polysome degradation. Ribonucleic acid from the isolated polysomes, when translated in vitro in a wheat germ system, yielded products ranging in size from about 12,000 to about 80,000 daltons, including at least two polypeptides that co-migrated with seed extract proteins in sodium dodecyl sulfate polyacrylamide gel electrophoresis. The nature of the translation products of free and membrane-associated RNA are distinctly different, with membrane-associated RNA yielding a higher proportion of polypeptides in the size range of 30,000 to 37,000 daltons. Analysis of membrane-associated 3'-terminal polyadenylyl-containing RNA in vitro translation products, by solubility in 70% ethanol and by immunoprecipitation, indicates that the 33,000- to 37,000-dalton polypeptides contain gliadins, and the analysis provides evidence that these proteins are synthesized in association with membranous cell organelles. Gliadin polypeptides synthesized in vitro are larger than authentic gliadins and probably are precursors which, in vivo, undergo modification to yield the smaller final products.
从小麦开花后20天收获的籽粒胚乳中分离出了数量大致相等的游离多核糖体和膜结合多核糖体。匀浆缓冲液中肝素的存在使多核糖体降解减到最少。分离出的多核糖体中的核糖核酸在小麦胚芽系统中进行体外翻译时，产生的产物大小在约12,000至约80,000道尔顿之间，包括至少两种在十二烷基硫酸钠聚丙烯酰胺凝胶电泳中与种子提取物蛋白质共迁移的多肽。游离RNA和膜结合RNA的翻译产物性质明显不同，膜结合RNA产生的分子量在30,000至37,000道尔顿范围内的多肽比例更高。通过在70%乙醇中的溶解度和免疫沉淀对膜结合的含3'-末端聚腺苷酸RNA的体外翻译产物进行分析，表明分子量为33,000至37,000道尔顿的多肽含有醇溶蛋白，并且该分析提供了证据证明这些蛋白质是与膜状细胞器结合合成的。体外合成的醇溶蛋白多肽比天然醇溶蛋白大，可能是前体，在体内经过修饰后产生较小的最终产物。
