The POK/AtVPS52 protein localizes to several distinct post-Golgi compartments in sporophytic and gam
June 29th, 2008 | by admin |The POK/AtVPS52 protein localizes to several distinct post-Golgi compartments in sporophytic and gametophytic cells.
The organization and dynamics of the plant endomembrane system require both universal and plant-specific molecules and compartments. The latter, despite the growing wealth of information, remains poorly understood. From the study of an Arabidopsis thaliana male gametophytic mutant, it was possible to isolate a gene named POKY POLLEN TUBE (POK) essential for pollen tube tip growth. The similarity between the predicted POK protein sequence and yeast Vps52p, a subunit from the GARP/VFT complex which is involved in the docking of vesicles from the prevacuolar compartment to the Golgi apparatus, suggested that the POK protein plays a role in plant membrane trafficking. Genetic analysis of Arabidopsis mutants affecting AtVPS53 or AtVPS54 genes which encode putative POK partners shows a transmission defect through the male gametophyte for all lines, which is similar to the pok mutant. Using a combination of biochemical approaches and specific antiserum it has been demonstrated that the POK protein is present in phylogenetically divergent plant species, associated with membranes and belongs to a high molecular weight complex. Combination of immunolocalization studies and pharmacological approaches in different plant cells revealed that the POK protein associates with Golgi and post-Golgi compartments. The role of POK in post-Golgi endomembrane trafficking and as a member of a putative plant GARP/VFT complex is discussed.
Guermonprez H, Smertenko A, Crosnier MT, Durandet M, Vrielynck N, Guerche P, Hussey PJ, Satiat-Jeunemaitre B, Bonhomme S.
INRA UR254, Station de Génétique et d\’Amélioration des Plantes, Institut Jean-Pierre Bourgin, Centre de Versailles-Grignon, F-78026 Versailles, France.