DIFFERENT PKC ISOFORMS PHOSPHORYLATE THE SMALL GTPASE RAB11

PAVAROTTI M; LEIVA N; CAPMANY A; COLOMBO MI; DAMIANIMT

Mar del Plata, Buenos Aires Republica Argentina

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

Sociedad Argentina de Investigaciones en Bioquimica y Biologia Molecular (SAIB).

The Rab family of monomeric GTPases regulates intracellular traffic. Some Rabs can be phosphorylated by specific kinases. This post-transductional modification changes Rab`s affinity for effectors as well as its function. Rab11 is localized to the endosomal recycling compartment and we have previously demonstrated that Rab11 regulates phagocytosis and recycling from phagosomes. It has been shown that upon sustained stimulation with phorbol esters, PKC á and âII translocate towards Rab11-enriched vesicles. Taken  together, these observations prompted us to investigate the possibility that Rab11 might serve as a substrate for PKC.We used on line predictive software to analyze Rab11`s putative phosphorylation sites and we found different consensus sites for basophilic serine/threonine kinases, like PKC. Then, we performed in vitro phosphorylation assays by use of [ P]ATP, GST-Rab11 and cytosol. The samples were resolved by SDS-PAGE and protein phosphorylation detected by autoradiography. Our results show that Rab11 is phosphorylated by kinases present in cytosol. To further analyze the role of PKC on Rab11 phosphorylation, we used different pure PKC isoforms. These experiments demonstrated that Rab11 is phosphorylated by the classic PKC , PKC II and the novel PKC . The phosphorylation of Rab11 is likely to be a regulatory event that affects the interaction with its effectors.