Functional Synergy between Rab5 Effector Rabaptin-5 and Exchange Factor Rabex-5 When Physically Associated in a Complex

• DOI: 10.1091/mbc.12.7.2219
• Publication Date: 2013-07-03T00:17:08Z
• Authors: Roger Lippé; Marta Miaczynska; Vladimir Rybin; Anja Runge; Marino Zerial
• Keywords: Rab; Small GTPase

Rab GTPases are central elements of the vesicular transport machinery. An emerging view is that downstream effectors these multiprotein complexes include nucleotide exchange factors to ensure coupling between GTPase activation and effector function. We have previously shown Rab5, which regulates various steps along early endocytic pathway, activated by a complex consisting Rabex-5, Rab5 factor, Rabaptin-5. postulated physical association two proteins necessary for their activity in Rab5-dependent membrane transport. To evaluate functional implications such formation, we reconstituted it with use recombinant characterized its properties. First, show Rabaptin-5 increases Rabex-5 on Rab5. Second, recruitment endosomes completely dependent Rabex-5. Third, formation essential endosome homotypic fusion. These results reveal synergy function analogous Rho GTPases.