THE ENDOPLASMIC-RETICULUM OF PLANT-CELLS AND ITS ROLE IN PROTEIN MATURATION AND BIOGENESIS OF OIL BODIES

The endoplasmic reticulum (ER) is the port of entry of proteins into t he endomembrane system, and it is also involved in lipid biosynthesis and storage. This organelle contains a number of soluble and membrane- associated enzymes and molecular chaperones, which assist the folding and maturation of proteins and the deposition of lipid storage compoun ds. The regulation of translocation of proteins into the ER and their subsequent maturation within the organelle have been studied in detail in mammalian and yeast cells, and more recently also in plants. These studies showed that in general the functions of the ER in protein syn thesis and maturation have been highly conserved between the different organisms. Yet, the ER of plants possesses some additional functions not found in mammalian and yeast cells. This compartment is involved i n cell to cell communication via the plasmodesmata, and, in specialize d cells, it serves as a storage site for proteins. The plant ER is als o equipped with enzymes and structural proteins which are involved in the process of oil body biogenesis and lipid storage. In this review w e discuss the components of the plant ER and their function in protein maturation and biogenesis of oil bodies. Due to the large number of c ited papers, we were not able to cite all individual references and in many cases we refer the readers to reviews and references therein. We apologize to the authors whose references are not cited.