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
Hélène
H
INRA UR254, Station de Génétique et d'Amélioration des Plantes, Institut Jean-Pierre Bourgin, Centre de Versailles-Grignon, F-78026 Versailles, France.
Smertenko
Andrei
A
Crosnier
Marie-Thérèse
MT
Durandet
Monique
M
Vrielynck
Nathalie
N
Guerche
Philippe
P
Hussey
Patrick J
PJ
Satiat-Jeunemaitre
Béatrice
B
Bonhomme
Sandrine
S
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D035264:Flowers / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D007150:Immunohistochemistry; D007425:Intracellular Membranes / Q000378:metabolism*; D018613:Microscopy, Confocal; D046912:Multiprotein Complexes / Q000378:metabolism; D009154:Mutation; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
D029681:Arabidopsis Proteins; D046912:Multiprotein Complexes; C532627:POK protein, Arabidopsis; D029701:Saccharomyces cerevisiae Proteins; C093602:VPS52 protein, S cerevisiae; D033921:Vesicular Transport Proteins