Class I FIPs, Rab11-binding proteins that regulate endocytic sorting and recycling.

Rab11 GTPase is an important regulator of endocytic membrane traffic. In the GTP-bound form Rab GTPases interact with effector proteins and each Rab-effector complex is proposed to regulate a unique trafficking step/event such as vesicle docking, budding, transport, or fusion. At least six Rab11 effectors (family of Rab11 interacting proteins, FIPs) have been identified and shown to interact with Rab11. Based on the sequence homology FIPs are divided in class I and class II subfamilies. Class I FIPs have been hypothesized to regulate the recycling of plasma membrane receptors. In contrast, class II FIPs have been implicated in regulating membrane traffic during more specialized cellular functions, such as cytokinesis. This chapter reviews the background and methodology required for characterizing interactions between FIPs and Rab11, as well as understanding their role in regulating endocytic membrane traffic.