Rab coupling protein associates with phagosomes and regulates recycling from the phagosomal compartment.

MARIA TERESA, DAMIANI; PAVAROTTI MARTÍN,; LEIVA NATALIA,; LINDSAY, A; MCCAFFREY M,; MARIA ISABEL COLOMBO

Traffic

Año: 2004 vol. 5 p. 785 - 797

1600-0854

Rab coupling protein (RCP) is a novel identified protein, that belongs to the Rab11-FIP family. RCP interacts specifically with Rab4 and Rab11, small GTPases that function as regulators along the endosomal recycling pathway. We used fluorescence confocal microscopy and biochemical approaches to evaluate the participation of RCP during particle uptake and phagosome maturation. In macrophages, RCP is predominantly membrane-bound and displays a punctate vesicular pattern throughout the cytoplasm. RCP colocalizes with transferrin and does not colocalize with lysotracker, a marker of lysosomes. Overexpression of H13, the carboxyl-terminal region of RCP which contains the rab binding domain, results in an abnormal endosomal compartment. Interestingly, we found that RCP is associated as discrete patches or protein domains to early phagosomal membranes. In macrophages, overexpression of full-length RCP stimulates recycling from the phagosomal compartment, whereas overexpression of H13 diminishes this vesicular transport step. It is likely that RCP acting as an intermediate between Rab4 and Rab11, regulates membrane trafficking along the phagocytic recycling pathway.