Diferent PKC Isofroms Phosphorylate the Small GTPase Rab11.

PAVAROTTI M; LEIVA N.; CAPMANY A; COLOMBO MI; DAMIANI MT

Mar del Plata, Buenos Aires, Argentina

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

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular. SAIB

The Rab family of monomeric GTPases regulates intracellulartraffic. Some Rabs can be phosphorylated by specific kinases. Thispost-transductional modification changes Rab`s affinity foreffectors as well as its function. Rab11 is localized to the endosomalrecycling compartment and we have previously demonstrated thatRab11 regulates phagocytosis and recycling from phagosomes. Ithas been shown that upon sustained stimulation with phorbol esters,PKC and II translocate towards Rab11-enriched vesicles. Takentogether, these observations prompted us to investigate thepossibility that Rab11 might serve as a substrate for PKC.We usedon line predictive software to analyze Rab11`s putativephosphorylation sites and we found different consensus sites forbasophilic serine/threonine kinases, like PKC. Then, we performedphosphorylation assays by use of [ P]ATP, GST-Rab11and cytosol. The samples were resolved by SDS-PAGE and proteinphosphorylation detected by autoradiography. Our results showthat Rab11 is phosphorylated by kinases present in cytosol. Tofurther analyze the role of PKC on Rab11 phosphorylation, we useddifferent pure PKC isoforms. These experiments demonstrated thatRab11 is phosphorylated by the classic PKC , PKC II and thenovel PKC . The phosphorylation of Rab11 is likely to be aregulatory event that affects the interaction with its effectors.