Nucleotide sequences from pbaseolln cDNA clones: the major storage proteins fromPhaseolus vulgarisare encoded by two unique gene families

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Abstract
The nucleotide sequences of eight partial and five full-length phaseolln cDNA clones show that phaseolin polypeptides are encoded by two distinct gene families whichdiffer in their coding regions by the presence or absence of two different size direct repeats. The α-type phaseolin polypeptides are encoded by genes containing direct repeats which encode 14 additional amino acids. Aside from these differences, the α-and β-type phaseolin genes show a high degree of homology (98%) which is consistent with these genes being derived from a common ancestral gene. Much of the heterogeneity found in the phaseolin polypeptides appears to be due to post-translational processing. Nucleotide sequence analysis demonstrates that the α-type genes contain only a few amino acid replacement substitutions and that the β-type genes appear to contain no amino acid replacement substitutions. S1 nuclease mapping shows a complex pattern for transcriptional initiation of phaseolln mRNA. Hydropathy analysis shows that phaseolin polypeptides are predominately hydrophlic, and that the two N-glycosyl recognition sites are located in different hydropathic environments.