Purification and functional properties of Rab11-FIP2.

Rab11-FIP2 is a 512-amino acid protein that was first identified in a screen for Rab11 interacting proteins. Database analysis revealed that it belongs to a family of proteins characterized by the presence of a highly homologous domain located at its carboxy-termini. This family was termed the Rab11 family of interacting proteins (Rab11-FIPs), as all members have been demonstrated to interact with Rab11. The Rab11-FIPs can be further subdivided into two classes. Rab11-FIP2 belongs to the class I Rab11-FIPs due to the presence of a C2 domain near its amino-terminus. RCP and Rip11 are the other class I family members. A number of proteins that interact directly with Rab11-FIP2, in addition to Rab11, have been identified. These include the EH domain-containing protein Reps1, the AP-2 subunit alpha-adaptin, the actin-based motor protein myosin Vb, and the chemokine receptors CXCR2 and CXCR4. It is hypothesized that Rab11-FIP2 functions to transport cargo, such as chemokine receptors and the EGF receptor, from the endocytic recycling compartment (ERC) to the plasma membrane.