Identification and characterization of a family of Rab11-interacting proteins

Rab11a is a small GTP-binding protein enriched in the pericentriolar plasma membrane recycling systems. We hypothesized that Rab11a-binding proteins e xist as downstream effectors of its action. Here we define a family of four Rab11-interacting proteins: Rab11-Family Interacting Protein 1 (Rab11-FIP1 ), Rab11-Family Interacting Protein 2 (Rab11-FIP2), Rab11-Family Interactin g Protein 3 (Rab11-FIP3), and pp75/Rip11. All four interacting proteins ass ociated with wild type Rab11a and dominant active Rab11a (Rab11aS20V) as we ll as Rab11b and Rab25. Rab11-FIP2 also interacted with dominant negative R ab11a (Rab11aS25N) and the tail of myosin Vb. The binding of Rab11-FIP1, Ra b11-FIP2, and Rab11-FIP3 to Rab11a was dependent upon a conserved carboxyl- terminal amphipathic alpha -helix. Rab11-FIP1, Rab11-FIP2, and pp75/Rip11 c olocalized with Rab11a in plasma membrane recycling systems in both non-pol arized HeLa cells and polarized Madin-Darby canine kidney cells. GFP-Rab11- FIP3 also colocalized with Rab11a in HeLa cells. Rab11-FIP1, Rab11-FIP2, an d pp75/Rip11 also coenriched with Rab11a and H+K+-ATPase on parietal cell t ubulovesicles, and Rab11-FIP1 and Rab11-FIP2 translocated with Rab11a and t he H+K+-ATPase upon stimulating parietal cells with histamine. The results suggest that the function of Rab11a in plasma membrane recycling systems is dependent upon a compendium of protein effectors.