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pubmed-2113051
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oai_dc
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pubmed-21130512008-05-01 Mechanism of regulation of actin polymerization by Physarum profilin Articles Physarum profilin reduces the rates of nucleation and elongation of F- actin and also reduces the extent of polymerization of actin at the steady state in a concentration-dependent fashion. The apparent critical concentration for polymerization of actin is increased by the addition of profilin. These results can be explained by the idea that Physarum profilin forms a 1:1 complex with G-actin and decreases the concentration of actin available for polymerization. The dissociation constant for binding of profilin to G-actin is estimated from the kinetics of polymerization of G-actin and elongation of F-actin nuclei and from the increase of apparent critical concentration in the presence of profilin. The dissociation constants for binding of Physarum profilin to Physarum and muscle actins under physiological ionic conditions are in the ranges of 1.4-3.7 microM and 11.3-28.5 microM, respectively. When profilin is added to an F-actin solution, profilin binds to G-actin which co-exists with F-actin, and then G- actin is dissociated from F-actin to compensate for the decrease of the concentration of free G-actin and to keep it constant at the critical concentration. At the steady state, free G-actin of the critical concentration is in equilibrium not only with F-actin but also with profilin-G-actin complex. The stoichiometry of 1:1 for the formation of complex between profilin and G-actin is directly shown by means of chemical cross-linking. The Rockefeller University Press 1984-06-01 /pmc/articles/PMC2113051/ /pubmed/6725405 Text en This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
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| repository_type |
Open Access Journal
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| institution_category |
Foreign Institution
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| institution |
US National Center for Biotechnology Information
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| building |
NCBI PubMed
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| collection |
Online Access
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| language |
English
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| format |
Online
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| title |
Mechanism of regulation of actin polymerization by Physarum profilin
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| spellingShingle |
Mechanism of regulation of actin polymerization by Physarum profilin
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| title_short |
Mechanism of regulation of actin polymerization by Physarum profilin
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| title_full |
Mechanism of regulation of actin polymerization by Physarum profilin
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| title_fullStr |
Mechanism of regulation of actin polymerization by Physarum profilin
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| title_full_unstemmed |
Mechanism of regulation of actin polymerization by Physarum profilin
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| title_sort |
mechanism of regulation of actin polymerization by physarum profilin
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| description |
Physarum profilin reduces the rates of nucleation and elongation of F- actin and also reduces the extent of polymerization of actin at the steady state in a concentration-dependent fashion. The apparent critical concentration for polymerization of actin is increased by the addition of profilin. These results can be explained by the idea that Physarum profilin forms a 1:1 complex with G-actin and decreases the concentration of actin available for polymerization. The dissociation constant for binding of profilin to G-actin is estimated from the kinetics of polymerization of G-actin and elongation of F-actin nuclei and from the increase of apparent critical concentration in the presence of profilin. The dissociation constants for binding of Physarum profilin to Physarum and muscle actins under physiological ionic conditions are in the ranges of 1.4-3.7 microM and 11.3-28.5 microM, respectively. When profilin is added to an F-actin solution, profilin binds to G-actin which co-exists with F-actin, and then G- actin is dissociated from F-actin to compensate for the decrease of the concentration of free G-actin and to keep it constant at the critical concentration. At the steady state, free G-actin of the critical concentration is in equilibrium not only with F-actin but also with profilin-G-actin complex. The stoichiometry of 1:1 for the formation of complex between profilin and G-actin is directly shown by means of chemical cross-linking.
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| publisher |
The Rockefeller University Press
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| publishDate |
1984
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| url |
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2113051/
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| _version_ |
1611412410013319168
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