The FIP domain is the Rab11-binding domain (RBD) at the C-terminus of a family of Rab11-interacting proteins (FIPs). The Rab proteins constitute the largest family of small GTPases (>60 members in mammals). Among them Rab11 is a well characterised regulator of endocytic and recycling pathways. Rab11 associates with a broad range of post-Golgi organelles, including recycling endosomes [1].

1: Structural basis for Rab11-dependent membrane recruitment of a family of Rab11-interacting protein 3 (FIP3)/Arfophilin-1. Shiba T, Koga H, Shin HW, Kawasaki M, Kato R, Nakayama K, Wakatsuki S; Proc Natl Acad Sci U S A. 2006;103:15416-15421. PMID:17030804