composition of newly synthesized proteins in the endoplasmic reticulum determines the transport pathways of soybean seed storage proteins

• Published in: The Plant journal : for cell and molecular biology 2004-10, Vol.40 (2), p.238-249
• Main Authors: Mori, T, Maruyama, N, Nishizawa, K, Higasa, T, Yagasaki, K, Ishimoto, M, Utsumi, S
• Format: Article
• Language: English
• Subjects: beta‐conglycinin; Biological and medical sciences; Biological Transport, Active; Botany; cotyledons; cultivars; Electrophoresis, Polyacrylamide Gel; endoplasmic reticulum; Endoplasmic Reticulum - metabolism; Fundamental and applied biological sciences. Psychology; Glycine max; Glycine max - cytology; Glycine max - metabolism; Glycine max - ultrastructure; glycinin; Golgi apparatus; Hydrogen-Ion Concentration; Metabolism; molecular sequence data; mutants; Mutation; Nitrogen metabolism; nucleotide sequences; Plant physiology and development; plant proteins; protein bodies; protein composition; protein storage vacuole; protein synthesis; protein transport; Proteins; seed storage protein; seeds; Seeds - metabolism; smooth dense bodies; soybean; Soybean Proteins - chemistry; Soybean Proteins - metabolism; Soybeans; storage proteins; vacuoles; vesicle transport
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313x.2004.02204.x

Glycinin (11S) and β-conglycinin (7S) are major storage proteins in soybean (Glycine max L.) seeds and accumulate in the protein storage vacuole (PSV). These proteins are synthesized in the endoplasmic reticulum (ER) and transported to the PSV by vesicles. Electron microscopic analysis of developing soybean cotyledons of the wild type and mutants with storage protein composition different from that of the wild type showed that there are two transport pathways: one is via the Golgi and the other bypasses it. Golgi-derived vesicles were observed in all lines used in this study and formed smooth dense bodies with a diameter of 0.5 to several micrometer. ER-derived protein bodies (PBs) with a diameter of 0.3-0.5 micrometer were observed at high frequency in the mutants containing higher amount of 11S group I subunit than the wild type, whereas they were hardly observed in the mutants lacking 11S group I subunit. These indicate that pro11S group I may affect the formation of PBs. Thus, the composition of newly synthesized proteins in the ER is important in the selection of the transport pathways.