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The complete nucleotide sequence of a cloned cDNA, designated pGA5A4B3822, corresponding to glycinin A5A4B3 mRNA was determined. Analysis of the cDNA insert revealed that it contained 1899 nucleotides of mRNA sequence with a 5'-terminal non-translated region of 31 nucleotides, a signal peptide region corresponding to 23 amino acids, an acidic subunit region (A,) corresponding to 97 amino acids, an acidic subunit region (A4) corresponding to 257 amino acids followed by a basic subunit region (B3) corresponding to 185 amino acids, and a 3'-terminal non-translated region of 182 nucleotides. These results show that the glycinin A4 subunit, which is not found to be linked to a basic subunit via a disulfide bond, is synthesized as a full-sized precursor, i.e. the A5A4B3 subunit complex, from a single mRNA, followed by post-translational processing to generate an intermediary subunit complex (A5-B3), covalently linked by a disulfide bond, and the mature A4 subunit, which may associate with the above subunit complex by non-covalent interactions. From the results obtained by the Chou-Fasman rules we speculated that the two post-translational cleavage sites of this subunit precursor might be processed by the same proteolytic enzyme.Glycinin, one of the principal storage proteins of soybean (Glycine max L., Merr.), is composed of six subunit pairs, each pair consisting of an acidic and a basic polypeptide that are linked via a disulfide bond, in one molecule [l -31. The subunit pairings of glycinin molecules are themselves a heterogeneous complex of A1,B2, AlbBlb, A2B1,, A3B4 and A5B3, which are covalently linked by disulfide bonds unlike the A4 subunit [4, 51.Recently Marco et al. have determined the partial genomic structure for a glycinin A2Bla subunit precursor [6]. We have also sequenced the double-stranded (ds) cDNA encoding a glycinin precursor for the A3 acidic and the B4 basic subunits [7]. These results conclusively showed that the specific acidic and basic components of every glycinin subunit pair are synthesized from the same mRNA as a single precursor, which may undergo a posttranslational processing event in order to form the individual linked subunit as speculated by Tumer et al. PI.A question is now raised regarding the origin of a glycinin acidic subunit, A4, which is not covalently linked to any basic subunits [5].In this communication, we report that the A4 subunit originates from a precursor of the A5A4B3 subunit complex, synthesized from a single mRNA by specific proteolytic processing. The deduced complete amino acid sequences of the A,, A4 and B3 subunits have also been determined. EXPERIMENTAL PROCEDUREHarvesting and storage of soybean cotyledons used in this experiment as described previously [7].Soybean cultivar Bonminori (Glycine rnax L., Merr.) was Construction of a soybean cotyledonary ds-cDNA recombinant plasmid library Double-stranded cDNA was synthesized from total poly(A)-containing RNA, sized, tailed, inserted and then transfected into Escherichia coli RR1 or E. coli GM 2150 as described ...

Prenylated aromatic compounds represent the chemical components in the glandular trichomes (lupulin glands) of hops (Humulus lupulus, Cannabinaceae), which give the characteristic flavor and taste of beer. To isolate cDNAs for prenyltransferase recognizing aromatic substrates in hops, we constructed a cDNA library from the lupulin glands and randomly sequenced 11,233 EST clones, to obtain 6,613 non-redundant EST sequence information. Among them, we found an aromatic prenyltransferase-like gene (HlPT-1), which possessed three features of the plant aromatic prenyltransferase family, i.e., a D-rich motif, membrane-spanning domains, and a transit peptide. The tissue-specific expression study of HlPT-1 in the intact plant revealed this gene to be highly expressed in hop corns (female flowers), especially in the lupulin glands. Subcellular localization analysis using GFP fusion proteins suggested that HlPT-1 was localized to plastids. Phylogenetic analysis predicted that the HlPT-1 gene evolved from homogentisate prenyltransferases involved with vitamin E and plastoquinone biosynthesis.