Phagocytosis: A Fundamental Process in Immunity

Figure 2

Signaling molecules concentrated in different parts of the membrane during phagocytosis. A phagocyte cell membrane around an IgG-opsonized particle is shown at different stages of phagosome formation. After initial recognition, membrane protrusions form a phagocytic cup (a), then pseudopods extend around the particle (b), and membrane fusion events at the distal end close the new vacuole (c), which is finally separated as an intracellular phagosome (d). Fluorescent protein chimeras were used to locate (colored lines) the signaling molecules PI(4,5)P2, DAG, PKC, PI(3,4,5)P3, PI(3)P, active (GTP-bound) Cdc42, Rac1, Rac2, and actin.

(a)

(b)

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(d)