Identification of a novel Rab11/25 binding domain present in eferin and Rip proteins

Rab11, a low molecular weight GTP-binding protein, has been shown to play a key role in a variety of cellular processes, including endosomal recycling , phagocytosis, and transport of secretory proteins from the trans-Golgi ne twork. In this study we have described a novel Rab11 effector, EF-hands-con taining Rab11-interacting protein (Eferin). In addition, we have identified a 20-amino acid domain that is present at the C terminus of Eferin and oth er Rab11/25-interacting proteins, such as Rip11 and nRip11. Using biochemic al techniques we have demonstrated that this domain is necessary and suffic ient for Rab11 binding in vitro and that it is required for localization of Rab11 effector proteins in vivo. The data suggest that various Rab effecto rs compete with each other for binding to Rab11/25 possibly accounting for the diversity of Rab11 functions.