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| Protein Migration along Stress Fibers |
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| N.M. McKenna and Y.-l. Wang (1986) |
| Exp. Cell Res. 167:95-105. |
| 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. This may create a flux of proteins toward the center of the cell. To address this possibility, we microinjected into chick cardiac fibroblasts with fluorescent labeled alpha-actinin, which incorporates readily into stress fibers. A laser microbeam was then used to create a bleached spot along the stress fiber. Flux of proteins should manifest as directional movement of the bleached spot. |
| Movement of Alpha-Actinin Away from the Distal End of Stress Fibers |
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Size = 280 x 184 pixels.
Size = 160 x 240 pixels.| The bleached spot is located near the center of the image and is indicated by an arrow. When the first bleached spot disappeared, through the exchange of bleached molecules with unbleached molecules in the cytoplasm, a new spot was created at the same place to allow continuous tracking of the movement. Bleached spot continued to move toward the center of the cell. For unknown reasons, this phenomenon was observed in only a fraction of cells. |