Mobility of filamentous actin in living cytoplasm.
Filamentous actin in living cultured cells was labeled by microinjecting trace amounts of rhodamine-phalloidin (rh-pha) as a specific, high-affinity probe. The microinjection caused no detectable effect on cell morphology or cell division. The distribution of rh-pha-labeled filaments was then examined in dividing cells using image-intensified fluorescence microscopy, and the exchangeability of labeled filaments along stress fibers was studied during interphase using fluorescence recovery after photobleaching. rh-pha showed a rapid concentration at the contractile ring during cell division. In addition, recovery of fluorescence after photobleaching occurred along stress fibers with a halftime as short as 8 min. These observations suggest that at least some actin filaments undergo continuous movement and reorganization in living cells. This dynamic process may play an important role in various cellular functions.
Doris W. Neustadt Laboratory of Cellular Structure, Department of Molecular and Cellular Biology, National Jewish Center for Immunology and Respiratory Medicine, Denver, Colorado 80206.
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Wang
D000199:Actins / Q000378:metabolism*; D000818:Animals; D002455:Cell Division; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism / Q000648:ultrastructure; D005456:Fluorescent Dyes; D051379:Mice; D008856:Microscopy, Fluorescence
D000199:Actins; D005456:Fluorescent Dyes