Nineteen cloned cDNAs encoding the α and α' -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 α' -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 nucelotides. 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 α and α' -subunits. Thus, the α and α' ' subunits are coded for by two closely related multigene families. The amino acid differences in the portions of the α and α' -subunits presented in this paper occur primarily near the carboxyl-terminus. The 3' noncoding nucleotides of the cloned α and α' -subunit DNAs are more highly conserved than are the coding nucleotides. This conservation suggests that the 3' untranslated sequences of the α and α' -subunit mRNAs are functional in the expression of the α and α' -subunit proteins or in the stabilization of the 7S subunit mRNAs.
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