Schuler M A, Ladin B F, Pollaco J C, Freyer G, Beachy R N
Nucleic Acids Res. 1982 Dec 20;10(24):8245-61. doi: 10.1093/nar/10.24.8245.
Cloned DNAs encoding four different proteins have been isolated from recombinant cDNA libraries constructed with Glycine max seed mRNAs. Two cloned DNAs code for the alpha and alpha'-subunits of the 7S seed storage protein (conglycinin). The other cloned cDNAs code for proteins which are synthesized in vitro as 68,000 d., 60,000 d. or 53,000 d. polypeptides. Hybrid selection experiments indicate that, under low stringency hybridization conditions, all four cDNAs hybridize with mRNAs for the alpha and alpha'-subunits and the 68,000 d., 60,000 d. and 53,000 d. in vitro translation products. Within three of the mRNA, there is a conserved sequence of 155 nucleotides which is responsible for this hybridization. The conserved nucleotides in the alpha and alpha'-subunit cDNAs and the 68,000 d. polypeptide cDNAs span both coding and noncoding sequences. The differences in the coding nucleotides outside the conserved region are extensive. This suggests that selective pressure to maintain the 155 conserved nucleotides has been influenced by the structure of the seed mRNA. RNA blot hybridizations demonstrate that mRNA encoding the other major subunit (beta) of the 7S seed storage protein also shares sequence homology with the conserved 155 nucleotide sequence of the alpha and alpha'-subunit mRNAs, but not with other coding sequences.
从用大豆种子信使核糖核酸构建的重组互补脱氧核糖核酸文库中，已分离出编码四种不同蛋白质的克隆脱氧核糖核酸。两个克隆的脱氧核糖核酸编码7S种子贮藏蛋白（伴大豆球蛋白）的α和α′亚基。其他克隆的互补脱氧核糖核酸编码的蛋白质，在体外合成时为分子量68,000道尔顿、60,000道尔顿或53,000道尔顿的多肽。杂交选择实验表明，在低严格度杂交条件下，所有四个互补脱氧核糖核酸都能与α和α′亚基以及分子量68,000道尔顿、60,000道尔顿和53,000道尔顿的体外翻译产物的信使核糖核酸杂交。在其中三种信使核糖核酸内，有一段155个核苷酸的保守序列，负责这种杂交。α和α′亚基互补脱氧核糖核酸以及分子量68,000道尔顿多肽互补脱氧核糖核酸中的保守核苷酸跨越编码和非编码序列。保守区域外编码核苷酸中的差异很大。这表明，维持155个保守核苷酸的选择压力受到种子信使核糖核酸结构的影响。核糖核酸印迹杂交表明，编码7S种子贮藏蛋白另一个主要亚基（β）的信使核糖核酸，也与α和α′亚基信使核糖核酸的155个核苷酸保守序列有序列同源性，但与其他编码序列没有同源性。
