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Updated: Jul 27, 2026

Actin Co-Sedimentation Assay; for the Analysis of Protein Binding to F-Actin
Published on: March 28, 2008
Two opposite effects of cofilin on the thermal unfolding of F-actin: a differential scanning calorimetric study
Irina V Dedova1, Olga P Nikolaeva, Valeria V Mikhailova
1Muscle Research Unit, Department of Anatomy and Histology, The University of Sydney, NSW 2006 Sydney, Australia.
Abstract:
Differential scanning calorimetry was used to examine the effects of cofilin on the thermal unfolding of actin. Stoichiometric binding increases the thermal stability of both G- and F-actin but at sub-saturating concentrations cofilin destabilizes F-actin. At actin:cofilin molar ratios of 1.5-6 the peaks corresponding to stabilized (66-67 degrees C) and destabilized (56-57 degrees C) F-actin are observed simultaneously in the same thermogram. Destabilizing effects of sub-saturating cofilin are highly cooperative and are observed at actin:cofilin molar ratios as low as 100:1. These effects are abolished by the addition of phalloidin or aluminum fluoride. Conversely, at saturating concentrations, cofilin prevents the stabilizing effects of phalloidin and aluminum fluoride on the F-actin thermal unfolding. These results suggest that cofilin stabilizes those actin subunits to which it directly binds, but destabilizes F-actin with a high cooperativity in neighboring cofilin-free regions.
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