RAB11, RAB14 AND RAB22: THREE SMALL GTPASES JOINEDAT THE ENDOCYTIC / RECYCLING PATHWAY

CAPMANY A; PAVAROTTI M; LEIVA N; MAGADÁN J; MAYORGA LS; DAMIANI MT

Mar del Plata, Buenos Aires, Argentina

Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.; 2007

Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular.

Rabs GTPases regulate intracellular trafficking and maintain structural identity by overseeing the vectorial transport of proteins and membranes between organelles. Rab proteins function as molecular switches by cycling between inactive GDP and active GTP bound forms. Each Rab protein controls a specific membrane transport step. Rab11 is present at the endocytic recycling compartment and TGN derived vesicles. Rab14 is localized at the Golgi/TGN and early endosomes. Rab22 is associated to early/sorting endosomes. As these Rabs share similar intracellular distribution, our goal was to analyze the degree of overlapping vesicular localization and function. These Rab proteins and some mutant forms were over-expressed fused to different fluorescent tags to assess their intracellular localization by confocal microscopy. Rab11wt and Rab14 wt almost completely colocalized at the endocytic recycling compartment and TGN vesicles. Rab14 wt and Rab22 wt were present in the same vesicles at the perinuclear region and also co-localized in some peripheral endosomes. The Rab14 GDP-bound form (Rab14S25N) and a truncated that does not associate to membranes (Rab14 GCGC) did not co-localize with Rab22wt.The results using mutants and different expression levels indicate that these proteins influence the localization of the each other and that they are present at the same domains on the membrane vesicle. These Rabs acting coordinately would control  molecular  trafficking  between endocytic/biosynthetic pathways.