F- and G-Actin Concentrations in Lamellipodia of Moving Cells
Figure 1
Dual bleach experiments demonstrate that monomeric GFP-actin recovers in the lamellipodium within 6 s after photobleach and is incorporated into F-actin only at the tip.
A shows the overview before bleach. Bar, 5 µm. B, C, Enlarged images of the region indicated by the white box in A show the bleached region immediately (B) and 20 s after bleach (C). Bar, 3 µm. Following the first bleach of the lamellipodium (green box in A), bleaching was continued in the region outlined by the box in B and C. Graph (D) shows the average intensity, measured in the red rectangular region, over time. The time between the two vertical dashed lines corresponds to the switch period between the end of the initial bleach and the initiation of the second bleach. Note that the intensity in the region marked by the red square stays constant during the second (continuous) bleach of the more distal region.