Interaction of actin with phalloidin: polymerization and stabilization of F-actin

Biochim Biophys Acta. 1975 Aug 19;400(2):407-14. doi: 10.1016/0005-2795(75)90196-8.

Abstract

The cyclic peptide phalloidin, one of the toxic components of Amanita phalloides prevented the drop of viscosity of F-actin solutions after the addition of 0.6 M KI and inhibited the ATP splitting of F-actin during sonic vibration. The data concerning ATP splitting are consistent with the assumption (a) that only 1 out of every 3 actin units of the filaments needs to be combined with phalloidin in order to suppress the contribution of these 3 actins to the ATPase activity of the filament and (b) that all actin units of the filaments can combine with phalloidin with a very high affinity. -halloidin did not only stabilize the actin-actin bonds in the F-actin structure but it also increased the rate of polymerization of G-actin to F-actin. The ability of F-actin to activate myosin ATPase was not affected by phalloidin. The tropomyosin-troponin complex did not prevent the stabilizing effect of phalloidin on the F-actin structure.

MeSH terms

  • Actins* / metabolism
  • Adenosine Triphosphatases / metabolism
  • Animals
  • Binding Sites
  • Drug Stability
  • Kinetics
  • Macromolecular Substances
  • Magnesium
  • Molecular Weight
  • Muscles / enzymology
  • Myosins / metabolism
  • Oligopeptides*
  • Phalloidine*
  • Potassium Chloride
  • Protein Binding
  • Rabbits
  • Viscosity

Substances

  • Actins
  • Macromolecular Substances
  • Oligopeptides
  • Phalloidine
  • Potassium Chloride
  • Adenosine Triphosphatases
  • Myosins
  • Magnesium