Istituto Biosintesi Vegetali, CNR, Via Bassini, 15, 20133 Milano, Italy.
EMBO J. 1985 May;4(5):1103-10. doi: 10.1002/j.1460-2075.1985.tb03746.x.
The family of zein proteins in maize consists of several prototypes whose amino sequence is characterized by a repetitive block structure. We have now isolated and characterized a new series of zein cDNA clones from a cDNA library made from protein-body polysomal mRNA. The nucleotide sequences and the hybrid-selected translation results indicate that anomalous zein genes with termination codons within the coding region are transcribed, translated and possibly accumulated into zein protein bodies. The sequence analysis of these new clones and their comparison with already characterized zein sequences, all from the same maize line, indicate a large variability in the amino acid sequence of the blocks both among the prototypes and within members of each prototype. Northern blot analysis of total RNA from endosperms at different maturation stages shows a differential expression of each prototype sequence with the production, within each family, of zein transcripts coding for discrete size classes of polypeptides. The results allow a better definition of the zein system, clarify the relationship between sequence types and polypeptide size classes, and suggest the possibility of inserting lysine codons to raise the nutritional value of the seed storage protein.
玉米醇溶蛋白家族由几个原型组成，其氨基酸序列的特点是具有重复的块结构。我们现在已经从蛋白体多核糖体 mRNA 制成的 cDNA 文库中分离和鉴定了一系列新的醇溶蛋白 cDNA 克隆。核苷酸序列和杂交选择翻译结果表明，带有编码区终止密码子的异常醇溶蛋白基因被转录、翻译并可能积累到醇溶蛋白体中。这些新克隆的序列分析及其与已鉴定的醇溶蛋白序列的比较，所有这些序列均来自同一玉米品系，表明在原型之间以及每个原型内的成员之间，块的氨基酸序列存在很大的可变性。不同成熟阶段胚乳总 RNA 的 Northern 印迹分析显示，每个原型序列的表达具有差异性，每个家族都产生编码不同大小类别的多肽的醇溶蛋白转录本。这些结果使醇溶蛋白系统得到了更好的定义，阐明了序列类型和多肽大小类之间的关系，并提出了插入赖氨酸密码子以提高种子贮藏蛋白营养价值的可能性。
