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Subunit exchange between smooth muscle myosin filaments

Filaments formed from phosphorylated smooth muscle myosin are stable in the presence of MgATP, whereas dephosphorylated filaments are disassembled to a mixture of folded monomers and dimers. The stability of copolymers of phosphorylated and dephosphorylated myosin was, however, unknown. Gel filtrati...

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Detalles Bibliográficos
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 1987
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2114742/
https://www.ncbi.nlm.nih.gov/pubmed/3500954
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collection PubMed
description Filaments formed from phosphorylated smooth muscle myosin are stable in the presence of MgATP, whereas dephosphorylated filaments are disassembled to a mixture of folded monomers and dimers. The stability of copolymers of phosphorylated and dephosphorylated myosin was, however, unknown. Gel filtration, sedimentation velocity, and pelleting assays were used to show that MgATP could dissociate dephosphorylated myosin from copolymers containing either rod and myosin or dephosphorylated and phosphorylated myosin. Copolymers were typically formed by dialyzing monomeric mixtures into filament-forming buffer but, unexpectedly, could also be formed within minutes of mixing preformed rod and myosin minifilaments. This result suggested that molecules can rapidly and extensively exchange between filaments, presumably via the monomeric pool of myosin in equilibrium with polymer. An exchange of molecules between filaments was demonstrated directly by electron microscopy using gold-labeled streptavidin or antibody to detect the exchanged species. By this approach it was shown that smooth muscle myosin filaments, like other macromolecular assemblies, are dynamic structures that can readily alter their composition in response to changing solvent conditions. Moreover, because folded monomeric myosin is unable to polymerize, these experiments suggest a mechanism for the disassembly of the filament by MgATP.
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spelling pubmed-21147422008-05-01 Subunit exchange between smooth muscle myosin filaments J Cell Biol Articles Filaments formed from phosphorylated smooth muscle myosin are stable in the presence of MgATP, whereas dephosphorylated filaments are disassembled to a mixture of folded monomers and dimers. The stability of copolymers of phosphorylated and dephosphorylated myosin was, however, unknown. Gel filtration, sedimentation velocity, and pelleting assays were used to show that MgATP could dissociate dephosphorylated myosin from copolymers containing either rod and myosin or dephosphorylated and phosphorylated myosin. Copolymers were typically formed by dialyzing monomeric mixtures into filament-forming buffer but, unexpectedly, could also be formed within minutes of mixing preformed rod and myosin minifilaments. This result suggested that molecules can rapidly and extensively exchange between filaments, presumably via the monomeric pool of myosin in equilibrium with polymer. An exchange of molecules between filaments was demonstrated directly by electron microscopy using gold-labeled streptavidin or antibody to detect the exchanged species. By this approach it was shown that smooth muscle myosin filaments, like other macromolecular assemblies, are dynamic structures that can readily alter their composition in response to changing solvent conditions. Moreover, because folded monomeric myosin is unable to polymerize, these experiments suggest a mechanism for the disassembly of the filament by MgATP. The Rockefeller University Press 1987-12-01 /pmc/articles/PMC2114742/ /pubmed/3500954 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/).
spellingShingle Articles
Subunit exchange between smooth muscle myosin filaments
title Subunit exchange between smooth muscle myosin filaments
title_full Subunit exchange between smooth muscle myosin filaments
title_fullStr Subunit exchange between smooth muscle myosin filaments
title_full_unstemmed Subunit exchange between smooth muscle myosin filaments
title_short Subunit exchange between smooth muscle myosin filaments
title_sort subunit exchange between smooth muscle myosin filaments
topic Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2114742/
https://www.ncbi.nlm.nih.gov/pubmed/3500954