Fig. 5. Clustering of acidic endosomal vesicles labeled with VatM-GFP at the membrane of new phagosomes, followed by the appearance of VatM-GFP in the phagosome membrane. Cells expressing VatM-GFP were fed yeast particles in the presence of Neutral Red (A) or TRITC-dextran (B-D). The TRITC-dextran was present for at least 30 minutes before addition of the yeast. (A) Neutral Red-positive vesicles rimmed with VatM-GFP clustered next to a phagosome (2 minutes after uptake of the yeast particle). The yeast particle is marked with a white diamond. (B-D) A large cell containing several yeast particles taking up a new yeast particle (marked with a white diamond); (B) phagosome membrane closing around the new yeast particle; (C) clustering of TRITC-dextran-positive, VatM-GFP-rimmed vesicles at the membrane of the new phagosome (70 seconds later); (D) similar intensity of VatM-GFP label in membranes of new and old phagosomes (4 minutes after uptake). Bars, 10 µm.