Endoxyloglucan transferase is localized both in the cell plate and in the secretary pathway destined for the apoplast in tobacco cells

Intracellular trafficking of enzymes responsible for constructing and modif ying the cell wall architecture in plants is mostly unknown. To examine the ir translocation pathways, we employed an endoxyloglucan transferase (EXGT) , a key enzyme responsible for forming and rearranging the cellulose/xylogl ucan network of the cell wall. We traced its intracellular localization in suspension-cultured cells of tobacco bright yellow-2 by means of green fluo rescent protein-fusion gene procedures as well as by indirect immunofluores cence. During interphase the protein was extensively secreted into the apop last via the endoplasmic reticulum-Golgi apparatus network, whereas during cytokinesis, the protein was exclusively located in the phragmoplast and ev entually transported to the cell plate. These results clearly indicate comm itment of EXGT protein to the construction of both the cell plate and the c ell wall. This study also visualized the process of phragmoplast developmen t at a level of vesicle translocation in the living cell.