Evolution of legume seed storage proteins--a domain common to legumins and vicilins is duplicated in vicilins.

We examined the primary sequence of canavalin, the major storage protein of jack beans, and found that an ancient sequence duplication accounts for 80% of the amino acid residues. Evidence for such a duplication was also found in the orthologous proteins phaseolin and pea vicilin. This sequence duplication presumably accounts for a structural duplication in the canavalin monomer observed by crystallographic analysis. One copy of this repeat was...