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Calcium modulates conformational changes in F‐actin induced by smooth muscle heavy meromyosin
Author(s) -
Avrova Stanyslava V,
Borovikov Yurii S,
Efimova Natalia N,
Chacko Samuel
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)00675-9
Subject(s) - heavy meromyosin , dephosphorylation , chemistry , actin , phosphorylation , biophysics , myosin , meromyosin , myosin light chain kinase , conformational change , calcium , biochemistry , myosin head , biology , phosphatase , organic chemistry
The effect of Ca 2+ on conformational changes in rhodamine‐phalloidin‐labeled F‐actin induced by binding of smooth muscle heavy meromyosin (HMM) with either phosphorylated or dephosphorylated regulatory light chains (LC 20 ) was studied by polarized fluorimetry. LC 20 phosphorylation caused alterations in the F‐actin structure typical of the force‐producing (strong‐binding) state, while dephosphorylation of the chains led to alterations typical of the formation of non‐force‐producing (weak‐binding) state of the actomyosin complex. The presence of Ca 2+ enhanced the effect of LC 20 phosphorylation and weakened the effect of LC 20 dephosphorylation. These data suggest that Ca 2+ modulates actin‐myosin interaction in smooth muscle by promoting formation of the strong‐binding state.