Deposition of matrix and crystalloid storage proteins during protein body development in the endosperm of Ricinus communis L. cv. Hale seeds [Castorbeans]

Protein bodies within the endosperm of castor bean (Ricinus communis L. cv. Hale) seeds arise from numerous small vacuoles which progressively become filled with storage protein, of which the crystalloid proteins make up approximately 70%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) shows that the crystalloids are a family of at least four proteins which reduce to two complementary groups after 2-mercaptoethanol treatment. The matrix, which comprises the remainder, has two major components, the soluble albumins and the lectins. The lectins are the only glycoproteins within the mature protein body. Both cytochemical staining and SDS-PAGE indicate that the synthesis of the crystalloid and the majority of matrix proteins begins some 20 days after pollination. Additionally, the crystalloid proteins are synthesized concurrently, whereas there is temporal variation in the synthesis of matrix proteins.