CHEMISTRY AND CELL BIOLOGY OF VACUOLAR PROTEINS OF SEEDS

Ultrastructural, cytochemical and immunochemical evidence obtained using different plant families supported a suggested model for the biosynthesis of the storage proteins of seeds. Aleurins of the legumin type were proposed to be homologous. The proposed homologues were usually hexamers or tetramers of a disulfide bridged subunit of the A-S-S-B type. The large observed variations in amino acid composition of the proposed homologues implied they were liberal proteins; i.e., large variations in the amino acid sequence of the subunits did not cause lethal effects nor change the function of the protein. The list of proposed legumin homologues included the legumins, glycinin, arachin, edestin and cocosin. Some unnamed cottonseed proteins also qualified.