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Synergy between actin depolymerizing factor/cofilin and profilin in increasing actin filament turnover
D Didry1, M F Carlier, D Pantaloni
1Dynamique du Cytosquelette, Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, 91198 Gif-sur-Yvette, France.
The Journal of Biological Chemistry
|September 25, 1998
Summary
Actin depolymerizing factor (ADF)/cofilin and profilin significantly enhance actin filament turnover. These proteins work together to increase actin dynamics, crucial for cellular processes.
Area of Science:
- Cell Biology
- Biochemistry
- Biophysics
Background:
- Actin dynamics are critical for cellular functions.
- Actin depolymerizing factor (ADF)/cofilin and profilin are key regulators of actin assembly.
- Understanding their precise mechanisms is essential for cell biology.
Purpose of the Study:
- To investigate the control mechanisms of steady-state actin assembly by ADF/cofilin and profilin.
- To quantify the effects of these proteins on actin filament dynamics.
- To elucidate the synergistic actions of ADF/cofilin and profilin.
Main Methods:
- Utilized Tbeta4 as an indicator for ATP-G-actin concentration.
- Performed experiments to measure actin filament turnover rates.
- Employed computer modeling with experimentally determined rate constants.
Main Results:
- ADF/cofilin increases steady-state ATP-G-actin concentration and filament depolymerization rate.
- Profilin synergizes with ADF/cofilin, enhancing actin filament turnover up to 125-fold.
- ADF/cofilin increases filament number, but this does not fully explain the turnover rate increase.
Conclusions:
- ADF/cofilin and profilin act complementarily at filament ends to enhance treadmilling processivity.
- Combined actions of ADF/cofilin and profilin lead to significant increases in actin filament dynamics.
- Computer modeling accurately predicts the distribution of actin species at steady state.