Rab11-FIP3, the Rab11-Family Interacting Protein 3, is associated to phagosomal membranes.

PAVAROTTI M; LEIVA N; COLOMBO MI; DAMIANI MT

Merlo. San Luis. Argentina.

Congreso; XXII Reunión Científica Anual de la Sociedad de Biología de Cuyo.; 2004

Sociedad de Biología de Cuyo

Rab11-FIP3 is a recently described protein that belongs to the class III Rab11-family binding proteins. It is also known as Arfophilin and Eferin. Rab11-FIP3 interacts with both Rab11 and ADP-ribosylation factor (ARF). It have been localized to the cleavage furrow during cytokinesis. We sought to investigate the Rab11-FIP3 subcellular localization in RAW macrophages. By immunofluorescence using an specific antibody, we found that the endogenous protein is predominantly membrane-bound and displays a punctate vesicular pattern throughout the cytoplasm. Similar results were obtained by confocal microscopy when we overexpressed Rab11-FIP3 fused to the green fluorescent protein. We have observed that Rab11-FIP3 colocalizes with Rab11 in the perinuclear endosomal compartment. Interestingly, we found that Rab11-FIP3 is associated as discrete patches to early phagosomal membranes. Overexpression of Rab11-FIP3244-756 a truncated form containing the Rab binding domain remains membrane-bound and associated to Rab11-positive structures. Our results suggest that Rab11-FIP3 by forming mutually exclusive complexes with Rab11, could serve a role in cellular processes that require the delivery of large amounts of membrane such as phagocytosis and plasma membrane recycling.