PHALLOIDIN ASSOCIATES WITH MICROFILAMENTS AFTER MICRO-INJECTION INTO TISSUE-CULTURE CELLS

  • 1 January 1980
    • journal article
    • research article
    • Vol. 21  (2) , 188-194
Abstract
Phalloidin is a drug, which specifically binds to F-actin. Tissue culture cells [rat kangaroo kidney P + K2 cells and mouse fibroblast 3T3 cells] were microinjected with phalloidin and the intracellular display of microfilament-associated proteins in such cells and in cytoskeletons prepared from them was followed by immunofluorescence microscopy using antibodies against actin, myosin, tropomyosin and .alpha.-actinin. When phalloidin concentrations of 0.2 mM were used, cells and cytoskeletons revealed, in addition to the stress fibers, aberrant microfilament arrangements (islands) underneath the upper membrane. These islands contain in addition to actin all the microfilament-associated proteins. Cytoskeletons were stabilized by phalloidin against the actin-depolymerization effect of 0.6 M KI. This resistance of phalloidin-bound actin was used to localize the drug, not only in the induced islands but also in the stress fibers. Phalloidin-injected cells showed the same response to cytochalasin B as normal cells and phalloidin did not interfere with ATP-induced contraction of glycerinated models. Phalloidin-stabilized filamentous actin can still give rise to contraction within the stress fiber system, and F-actin bound to phalloidin may be translocated within the cell.