Endocytic Rabs in membrane trafficking and signaling.

The endolysosomal system controls the trafficking of proteins between the plasma membrane and the degradative environment of the lysosome. The early endosomal Rab5 and the late endosomal Rab7 GTPases have a key role in the transport along the endocytic pathway by recruiting tethering factors such as the hexameric CORVET and HOPS complexes that promote membrane fusion. Both Rabs are also involved in signaling at endosomal membranes and linked to amino acid sensing and autophagy, indicating that their role in trafficking may be connected to signal transduction and adaptation during cell stress. Here, we will summarize the current knowledge on the role of both Rab GTPases on both processes and discuss the possible crosstalk between them.