Abstract
MAG3 is involved in intracellular transport of seed storage protein.
Seed storage proteins are synthesized on the endoplasmic reticulum (ER) as precursors and then transported to protein storage vacuoles, where they are processed into mature forms. Here, we isolated and characterized an Arabidopsis mutant, maigo3 (mag3), that accumulated the precursors of storage proteins in dry seeds. mag3 seed cells contained a number of novel structures with electron-dense cores. Because these structures were surrounded by ribosomes, they seem to be derived from ER. MAG3 gene encodes an unknown protein, which contains a number of coiled-coil regions and one transmembrane domain at the C-terminus. Biochemical analysis revealed that MAG3 protein localized on the ER membrane, and that the transmembrane domain is responsible for ER localization and function of MAG3 protein. Our findings suggest that MAG3 protein is involved in the protein transport between ER-Golgi complex. Functional model of MAG3 will be discussed. 944
Reference: Li et al. (2006) Plant Cell, 18, 3535-3547.
