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Fig. 2. InlB-induced actin-based processes. (A) InlB-mediated internalization by
the `zipper-like' mechanism. On the left is a transmission electron microscopy
section of an InlB-coated bead being internalized into an epithelial cell
[reproduced from (Braun et al.,
1998)]. The particle is engulfed within tightly adherent
membranous structures before lying in a phagocytic vacuole. Note the presence
of small membrane projections at the entry site of the particle. On the right,
the F-actin phagocytic cup is stained with FITC-phalloidin (in green) at the
entry site of two InlB-coated beads (in blue). (B) InlB-induced membrane
ruffling in Vero cells. A cell untreated (left) or incubated with 4.5 nM
purified InlB for 5 minutes (right) and stained with FITC-phalloidin to detect
F-actin.