Figure 3.

Conditions that inhibit in vitro phagosome-endosome fusion. The effects are shown of cyto D (A), phalloidin-stabilized F-actin (B), rhoGDI (C), and 10 mM BDM (D) on the in vitro fusion of phagosomes with endocytic organelles in the presence of an ATP-regenerating system. These reagents were mixed into the standard fusion assay and the transfer of bHRP to phagosomes were expressed as nanograms of HRP bound to a fixed number of avidin beads. The low-ATP arrow shows the average values obtained under ATP-depleting conditions for three concentration points. In each case the means of one duplicate experiment is shown out of a total of three experiments done in duplicates. Although the absolute values obtained varied from one experiment to the next the patterns shown were consistently seen.