Abstract
GEF (Guanine nucleotide Exchange Factor) participates in vesicular transport. Rice glutelin is synthesized on endoplasmic reticulum as a precursor, which is transported via Golgi to protein storage vacuole. In glup6 mutation for the gene encoding GEF, the proglutelin is accumulated in the endosperm. But the function of GEF to the intracellular transport of proglutelin is not clear. Immunofluorescence microscopy of the glup6 endosperm demonstrated that the novel structure including proglutelin was observed in glup6 endosperm. This structure included also β-glucan, which is synthesized at the Golgi apparatus. Confocal microscopy of glup6 endosperm indicated that the structure included the membrane protein of the prevacuolar compartment and the Golgi. These results suggest that the proglutelin trafficking from the Golgi is significantly distorted in glup6. The granules including proglutelin were observed within the cell wall in early developing stage, while the granules were disappeared in late developing stage.
On a conclusion, GEF functions in the formation of endomembrane system in rice endosperm and participates in intracellular transport of proglutelin to PSV.
