Actin polymerization and ATP hydrolysis |
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| Institution: | 1. Young Researchers and Elites Club, North Tehran Branch, Islamic Azad University, Tehran, Iran;2. Department of Fisheries, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran;3. Fisheries Department, Faculty of Natural Resources, Urmia University, Urmia, Iran;4. Biology Department, Faculty of Sciences, Mohaghegh Ardabili University, Ardabil, Iran;1. Department of Mathematics, University of California at Davis, Davis, California;2. Department of Mathematics, Department of Physics and Astronomy, Center for Complex Biological Systems, University of California at Irvine, Irvine, California;1. London Centre for Nanotechnology, University College London, London WC1H 0AH, UK;2. Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK;3. Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, QC H3N 3J7, Canada;4. Department of Physics and Astronomy, University College London, London WC1E 6BT, UK;5. Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany;6. International Institute of Molecular and Cell Biology, Warsaw 02-109, Poland;7. Medical Research Council Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK;8. Institute of Child Health, University College London, London WC1N 1EH, UK;9. Laboratoire d’Enzymologie et Biochimie Structurales, CNRS, 91198 Gif-sur-Yvette, France;2. Department of Bioengineering and Biophysics Program, University of California, Berkeley, 648 Stanley Hall MC 1762, Berkeley, CA 94720, USA;3. Physical Biosciences Division, Lawrence Berkeley National Laboratory, 648 Stanley Hall MC 1762, Berkeley, CA 94720, USA;4. Advance Science Research Center, City University of New York, 85 St. Nicholas Terrace, New York, NY 10031, USA;5. Department of Chemistry, University of California, Berkeley, 207 Gilman Hall, Berkeley, CA 94720, USA |
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| Abstract: | This paper surveys several aspects of the consequences of ATP hydrolysis associated with actin polymerization, and their physiological implications. ATP hydrolysis occurs on F-actin in two subsequent reactions, cleavage of ATP followed by the slower release of Pi. The latter reaction is linked to a conformation change of the actin subunit that causes a destabilization of the actin-actin interactions in the filament, i.e., a structural change of the filament. The nature of the nucleotide bound to terminal subunits therefore affects the dynamics of actin filaments. It is shown that this regulation is different at the two ends, terminal F-ADP-Pi subunits being present at steady state at the barbed end, while F-ADP-subunits are present at the pointed end. While cleavage of ATP on F-actin is irreversible, Pi release is reversible, which allows the regulation of filament dynamics by cellular Pi. The nature of the divalent metal ion — Ca2+ or Mg2+ — tightly bound to actin, in direct interaction with ATP, also affects the conformation of actin and the rate of ATP hydrolysis, therefore regulating actin dynamics. Finally, the rate of nucleotide exchange on G-actin is relatively slow, which allows the critical concentration to increase with the number of filaments in ATP, a property largely used by the cell via the action of severing proteins. |
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