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  • Title: Selective binding of gelsolin to actin monomers containing ADP.
    Author: Laham LE, Lamb JA, Allen PG, Janmey PA.
    Journal: J Biol Chem; 1993 Jul 05; 268(19):14202-7. PubMed ID: 8390984.
    Abstract:
    The rate of reaction and the stoichiometry of binding between gelsolin and actin monomers depends on adenine nucleotides. In the presence of Ca2+ but not Mg2+, gelsolin retains the ability to sever actin filaments when incubated for more than 20 min with an excess of G-actin in the presence of ATP but loses severing activity within seconds when mixed with G-actin in ADP. Immunoprecipitation of gelsolin removes more actin from ADP than from ATP solutions. Monomeric ATP-actin in 2 mM MgCl2 and 150 mM KCl slowly destroys the filament-severing activity of gelsolin with kinetics that are first order in actin concentration and with an apparent bimolecular rate constant of 0.021 +/- 0.007 microM-1 s-1. Coincident with the slow complex formation in MgCl2, the actin bound to the calcium-sensitive actin binding domain of gelsolin hydrolyzes its ATP to ADP. These results suggest a further level of gelsolin regulation and a functional similarity between actin and GTP-binding proteins.
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