Schuler M A, Schmitt E S, Beachy R N
Nucleic Acids Res. 1982 Dec 20;10(24):8225-44. doi: 10.1093/nar/10.24.8225.
Nineteen cloned cDNAs encoding the alpha and alpha'-subunits of the 7S seed storage protein in the soybean, Glycine max, have been isolated from a recombinant cDNA library constructed with mRNA from maturing seeds. In addition, a gene encoding an alpha'-subunit has been isolated from a recombinant Charon 4A phage library containing genomic Glycine max DNA. The cloned DNAs have been divided, on the basis of their endonuclease sites, into two main classes of sequences which differ in approximately 6% of their nucleotides. Whereas the proteins encoded within each DNA class are nearly identical, the proteins encoded by the two different classes of soybean DNAs are distinct and correspond to alpha and alpha'-subunits. Thus, the alpha and alpha'-subunits are coded for by two closely related multigene families. The amino acid differences in the portions of the alpha and alpha'-subunits presented in this paper occur primarily near the carboxyl-terminus. The 3' noncoding nucleotides of the cloned alpha and alpha'-subunit DNAs are more highly conserved than are the coding nucleotides. This conservation suggests that the 3' untranslated sequences of the alpha and alpha'-subunit mRNAs are functional in the expression of the alpha and alpha'-subunit proteins or in the stabilization of the 7S subunit mRNAs.
从用成熟种子的mRNA构建的重组cDNA文库中，已分离出19个编码大豆（Glycine max）7S种子贮藏蛋白α和α'亚基的克隆cDNA。此外，还从一个含有大豆基因组DNA的重组Charon 4A噬菌体文库中分离出一个编码α'亚基的基因。根据其内切酶位点，已将克隆的DNA分为两个主要的序列类别，它们的核苷酸约有6%不同。虽然每个DNA类别内编码的蛋白质几乎相同，但由两类不同的大豆DNA编码的蛋白质是不同的，分别对应于α和α'亚基。因此，α和α'亚基由两个密切相关的多基因家族编码。本文中α和α'亚基部分的氨基酸差异主要出现在羧基末端附近。克隆的α和α'亚基DNA的3'非编码核苷酸比编码核苷酸保守性更高。这种保守性表明，α和α'亚基mRNA的3'非翻译序列在α和α'亚基蛋白的表达或7S亚基mRNA的稳定中起作用。
