RAB11 Family Interacting Protein 4 (RAB11FIP4)

Proteins of the large Rab GTPase family have regulatory roles in the formation, targeting, and fusion of intracellular transport vesicles. RAB11FIP4 is one of many proteins that interact with and regulate Rab GTPases. The deduced 637-amino acid protein contains an N-terminal EF-hand domain, a C-terminal coiled-coil domain, ERM motif, and Rab11-binding domain. RAB11FIP4 shares 92% homology with its mouse ortholog. Immunofluorescence studies colocalized RAB11FIP4 with RAB11A to the endosomal recycling compartment (ERC) and to endosomal membranes.RAB11FIP4 interacted specifically with active RAB11, demonstrating no interaction with an S25N-mutant RAB11 or with a constitutively active RAB11 mutant. RAB11FIP4 showed no interaction with other RAB family members.