CORONIN INVOLVED IN PHAGOCYTOSIS - DYNAMICS OF PARTICLE-INDUCED RELOCALIZATION VISUALIZED BY A GREEN FLUORESCENT PROTEIN TAG

Coronin is a protein involved in cell locomotion and cytokinesis of Di ctyostelium discoideum. Here we show that coronin is strongly enriched in phagocytic cups formed in response to particle attachment. A fusio n of coronin with green fluorescent protein (GFP) accumulates in the c ups within less than 1 min upon attachment of a particle and is gradua lly released from the phagosome within 1 min after engulfment is compl eted, Phagocytic cup formation competes with leading edge formation an d can be interrupted at any stage, When the cup regresses, coronin dis sociates from the site of accumulation, TRITC-labeled yeast cells have been used to assay phagocytosis quantitatively in wild-type and coron in-null cells, In the mutant, the rate of uptake is reduced to about o ne third, which shows that coronin contributes to the efficiency of ph agocytosis to about the same extent as it improves the speed of cell l ocomotion.