Rab-Coupling Protein (RCP) is an approximately 80-kDa, hydrophilic protein that belongs to a recently identified family of proteins that is characterized by its ability to interact with Rab11 via a highly homologous Rab-binding domain positioned at its carboxy-termini. Five members of this family have been identified; however, a number of these Rab11-FIPs, including RCP and Rip11, have several splice isoforms. RCP is involved in regulating transport of membrane-bound vesicles from the endocytic recycling compartment to the plasma membrane, and it can be found at both locations within the cell.