Figure 3.

The relation between PIP5K-γ deficiency, actin, particle attachment, and FcγR clustering defects. (A) Rescue of cell shape and actin by PIP₂ shuttling. BMM with or without exogenously added PIP₂ were stained with phalloidin. (B) Rescue of particle attachment by PIP₂ delivery. Binding indices (n > 100) are expressed as the percentage of WT BMM without PIP₂. (C) Rescue of particle attachment by Latr B. Cells were incubated with Latr B for 5 min at 37°C before incubation with particles at 4°C (n > 70). (D) Inhibition of particle attachment to WT BMM by Jasp. Cells were incubated with 1 µM Jasp at 37°C for 30 min before the addition of IgG beads (n > 50). (E) Inhibition of FcγR clustering in WT BMM by Jasp. (left) Fluorescence staining of FcγR–IC clusters. (right) Cluster size quantitation (n > 1,000). Error bars indicate SEM. (F) Attenuation of IC-induced ERK phosphorylation by Jasp. Cells pretreated with or without Jasp were incubated with IC at 4°C for 20 min and warmed to 37°C. Bars, 10 µm.