RESUMO

In eukaryotic cells, proteins destined for secretion are translocated into the endoplasmic reticulum (ER) and packaged into so-called COPII-coated vesicles. In the ER exit sites (ERES), COPII has the capacity of deforming the lipid bilayer, where it modulates the selective sorting and concentration of cargo proteins. In this study, we analyze the involvement of Rab1b in COPII dynamics and function by expressing either the Rab1b negative-mutant (Rab1N121I) or the Rab1b GTP restricted mutant (Rab1Q67L), or performing short interference RNA-based knockdown. We show that Rab1b interacts with the COPII components Sec23, Sec24 and Sec31 and that Rab1b inhibition changes the COPII phenotype. FRAP assays reveal that Rab1b modulates COPII association/dissociation kinetics at the ERES interface. Furthermore, Rab1b inhibition delays cargo sorting at the ER exit sites. We postulate that Rab1b is a key regulatory component of COPII dynamics and function.

Assuntos

Vesículas Revestidas pelo Complexo de Proteína do Envoltório/metabolismo , Proteínas rab1 de Ligação ao GTP/metabolismo , Animais , Vesículas Revestidas pelo Complexo de Proteína do Envoltório/genética , Vesículas Revestidas pelo Complexo de Proteína do Envoltório/fisiologia , Retículo Endoplasmático/genética , Retículo Endoplasmático/metabolismo , Células HEK293 , Humanos , Transporte Proteico/genética , RNA Interferente Pequeno/genética , Ratos , Proteínas rab1 de Ligação ao GTP/genética