The binding of fluorescent phallotoxins to actin in myofibrils

Danuta Szczesna, Sherwin S. Lehrer

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Fluorescence microscope observation of myofibrils incubated with rhodamine-phalloidin and coumarine-phallacidin showed an initial appearance of fluorescence bands at the Z-lines and near the middle of the sarcomeres indicating preferential binding of dye to actin subunits located at both actin filament ends. After long incubation times (1-3 h) however, a final pattern is reached which consists of fluorescent Z-lines in the center of uniformly labelled actin bands, with greater fluorescence in the Z-lines than in the uniform region outside the Z-lines. Increasing the temperature or the ionic strength increased the rate of change to the final pattern. These data indicate: (1) that the ends of the actin filament are kinetically more accessible to phallotoxins; (2) at long times when equilibrium binding presumably occurs, the concentration of actin subunits in the Z-band is greater than in the rest of the sarcomere.

Original languageEnglish (US)
Pages (from-to)594-597
Number of pages4
JournalJournal of Muscle Research and Cell Motility
Issue number6
StatePublished - Dec 1993
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Cell Biology


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