title: Rab11-FIP4 interacts with Rab11 in a GTP-dependent manner and its overexpression condenses the Rab11 positive compartment in HeLa cells.
abstract: We have recently identified Rab11-FIP4 as the sixth member of the Rab11-FIP family of Rab11 interacting proteins. Here, we demonstrate that Rab11-FIP4 interacts with Rab11 in a GTP-dependent manner and that its C-terminal region allows the protein to self-interact and interact with pp75/Rip11, Rab11-FIP2, and Rab11-FIP3. However, Rab11-FIP4 does not appear to interact directly with Rab coupling protein (RCP). We investigated the subcellular localisation of Rab11-FIP4 in HeLa cells and show that it colocalises extensively with transferrin and with Rab11. Furthermore, when overexpressed, it causes a condensation of the Rab11 compartment in the perinuclear region. We demonstrate that the carboxy-terminal region of Rab11-FIP4 (Rab11-FIP4(C-ter)) is necessary and sufficient for its endosomal membrane association. Expression of Rab11-FIP4(C-ter) causes a dispersal of the Rab11 compartment towards the cell periphery and does not inhibit transferrin recycling in HeLa cells. It is likely that Rab11-FIP4 serves as a Rab11 effector in a Rab11 mediated function other than transferrin recycling.
authors.affiliation: Cell and Molecular Biology Laboratory, Department of Biochemistry, University College Cork, Lee Maltings, Prospect Row, Cork, Ireland.
authors.forename: Deborah M E
authors.initials: DM
authors.lastname: Wallace
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Lindsay
authors.forename: Alan G
authors.initials: AG
authors.lastname: Hendrick
authors.forename: Mary W
authors.initials: MW
authors.lastname: McCaffrey
mesh_terms: D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002451:Cell Compartmentation; D011992:Endosomes / Q000737:chemistry*; D006160:Guanosine Triphosphate / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007425:Intracellular Membranes / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D021381:Protein Transport; D017384:Sequence Deletion; D014162:Transfection; D014168:Transferrin / Q000378:metabolism; D020691:rab GTP-Binding Proteins / Q000032:analysis* / Q000378:metabolism*; D000099193:rab11 GTP-Binding Proteins
chemical_list: D002352:Carrier Proteins; D006160:Guanosine Triphosphate; D008565:Membrane Proteins; D014168:Transferrin; D020691:rab GTP-Binding Proteins; D000099193:rab11 GTP-Binding Proteins; C470424:RAB11FIP4 protein, human