PLANT PHYSIOLOGY , Vol 102, Issue 1 61-69, Copyright © 1993 by American Society of Plant Biologists
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CELL BIOLOGY AND SIGNAL TRANSDUCTION |
Wheat (Triticum aestivum L.) [gamma]-Gliadin Accumulates in Dense Protein Bodies within the Endoplasmic Reticulum of Yeast
N. Rosenberg, Y. Shimoni, Y. Altschuler, H. Levanony, M. Volokita and G. Galili
Department of Plant Genetics (N.R., Y.S., Y.A., H.L., G.G.) and Department of Biochemistry (M.V.), The Weizmann Institute of Science, Rehovot 76100, Israel
Following their sequestration into the endoplasmic reticulum (ER), wheat
storage proteins may either be retained and packaged into protein bodies
within this organelle or transported via the Golgi to vacuoles. We
attempted to study the processes of transport and packaging of wheat
storage proteins using the heterologous expression system of yeast. A
wild-type wheat [gamma]-gliadin, expressed in the yeast cells, accumulated
mostly within the ER and was deposited in protein bodies with similar
density to natural protein bodies from wheat endosperm. This suggested that
wheat storage proteins contain sufficient information to initiate the
formation of protein bodies in the ER of a heterologous system. Only a
small amount of the [gamma]-gliadin was transported to the yeast vacuoles.
When a deletion mutant of the [gamma]-gliadin, lacking the entire
N-terminal repetitive region, was expressed in the yeast cells, the mutant
was unable to initiate the formation of protein bodies within the ER and
was completely transported to the yeast vacuole. This strongly indicated
that the information for packaging into dense protein bodies within the ER
resides in the N-terminal repetitive region of the [gamma]-gliadin. The
advantage of using yeast to identify the signals and mechanisms controlling
the transport of wheat storage proteins and their deposition in protein
bodies is discussed.
