Overview Cell Structures Cell Migration Cell Division  

Protein Flux along Stress Fibers

McKenna and Wang, Exp. Cell Res. 167:95-105 (1986)

Stress fibers are large bundles of actin-myosin filaments and accessory proteins. A number of observations suggest that actin may assemble actively at the distal end of stress fibers, where they interact with the plasma membrane, thereby creating a flux of proteins toward the center of the cell. To address this possibility, chick cardiac fibroblasts were injected with fluorescently labeled alpha-actinin, a stress fiber component. A bleached spot was then created with a laser micro-beam to allow the tracking of protein flux.

Movement of Alpha-Actinin Away from the Distal End of Stress Fibers

The bleached spot is located near the center of the image as indicated by an arrow. When the first bleached spot disappeared, a new spot was created at the same place to allow continuous tracking. Bleached spot continues to move toward the center of the cell, although the phenomenon was observed in only a fraction of cells at the time. Research 20 years later suggests that the variability may be related to mechanical signals (see Guo and Wang, 2008). Recording time, 19 min (upper) and 20 min (lower).