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 maintainstructural identity by overseeing the vectorial transport of proteinsand membranes between organelles. Rab proteins function asmolecular switches by cycling between inactive GDP and activeGTP bound forms. Each Rab protein controls a specific membranetransport step. Rab11 is present at the endocytic recyclingcompartment and TGN derived vesicles. Rab14 is localized at theGolgi/TGN and early endosomes. Rab22 is associated toearly/sorting endosomes. As these Rabs share similar intracellulardistribution, our goal was to analyze the degree of overlappingvesicular localization and function. These Rab proteins and somemutant forms were over-expressed fused to different fluorescenttags to assess their intracellular localization by confocalmicroscopy. Rab11wt and Rab14 wt almost completely colocalizedat the endocytic recycling compartment and TGNvesicles. Rab14 wt and Rab22 wt were present in the same vesiclesat the perinuclear region and also co-localized in some peripheralendosomes. The Rab14 GDP-bound form (Rab14S25N) and atruncated that does not associate to membranes (Rab14 GCGC)did not co-localize with Rab22wt.The results using mutants anddifferent expression levels indicate that these proteins influence thelocalization of the each other and that they are present at the samedomains on the membrane vesicle. These Rabs acting coordinatelywould c o n t r o l m o l e c u l a r t r a f f i c k i n g be t w e e nendocytic/biosynthetic pathways.