Figure 5

Fig. 5. Localization of cross-linking proteins in fibroblast cytoskeleton. (a-c) Fluorescence microscopy and corresponding intensity profiles (a'-c') of Xenopus (a, c) or human 356 (b) fibroblast lamellipodia double stained with TRITC-phalloidin (red) and either p21 (a, a'), ABP 280 (b, b') or a-actinin (c, c') antibodies (green). Protein/actin ratio at the leading edge of the lamellipodium is high for Arp2/3 complex (a, a'), medium for ABP-280 (b, b'), and low for a actinin (c, c') compared to internal actin structures. (d-i) Immunoelectron microscopy of the cell edge (d - f) or interior (g - i) of CD-treated Xenopus (d, f, g, i) or human 356 (e, h) fibroblasts stained with p21 (d, g), ABP-280 (e, h), or a-actinin (f, i) primary antibody and 10 nm (d, e, g, h) or 18 nm (f, i) gold-conjugated secondary antibody. Gold particles (yellow) reveal Arp2/3 complex at Y-junctions at cell edge, and ABP-280 and a-actinin at filament crossovers in the cell interior. Bars, 1 µm (a-c), 0.1 µm (d-i).