Rab11FIP

Rab11 family-interacting proteins (Rab11-FIPs) are a family of cytosolic effector proteins that bind the small GTPase Rab11 and regulate endocytic recycling. They associate with Rab11-positive recycling endosomes and help coordinate the movement and sorting of membrane cargo back to the plasma membrane, thereby influencing receptor recycling, membrane composition, and surface signaling.

The Rab11-FIP family comprises several members, commonly designated Rab11-FIP1 through Rab11-FIP5, with additional members reported in some species. All Rab11-FIPs interact with Rab11 via a conserved Rab11-binding region usually located toward the C-terminus. Most family members also possess additional domains or motifs that facilitate interactions with cytoskeletal elements, motor proteins, or other trafficking factors, enabling linkage of recycling endosomes to microtubules and actin networks.

Functions attributed to Rab11-FIPs include regulating the recycling of a range of cargo proteins, such as nutrient receptors and adhesion molecules, and coordinating endosome movement and cargo sorting. Their activity supports processes such as cell polarity, migration, and receptor resensitization after endocytosis. The specific roles and cargo preferences vary among individual Rab11-FIP family members, reflecting their distinct interaction partners and localization patterns within the cell.

In research contexts, Rab11-FIPs are studied for their roles in intracellular trafficking and their impact on cellular signaling and surface receptor presentation. Disruptions or alterations in Rab11-FIP–mediated recycling can affect endosome dynamics and have been explored in relation to cancer progression, development, and pathogen trafficking. Rab11-FIP serves as a general label for this family of Rab11 effectors rather than a single protein.