Conformations of Vertebrate Striated Muscle Myosin Monomers in Equilibrium with Filaments
| Autor: | Chiho Naraoka, Michio Yazawa, Tsunehisa Takahashi, Tsuyoshi Katoh, Chikako Fukukawa |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
Protein Folding
Myofilament Conformational change Protein Conformation Swine Size-exclusion chromatography macromolecular substances Myosins Biology Biochemistry Phosphates Protein filament chemistry.chemical_compound Myosin head Cardiac Myosins Naphthalenesulfonates Myosin Animals Muscle Skeletal Molecular Biology Fluorescent Dyes Myocardium Myosin Subfragments Muscle Smooth General Medicine Actin Cytoskeleton Monomer chemistry Vertebrates Biophysics |
| Zdroj: | Journal of Biochemistry. 126:34-40 |
| ISSN: | 0021-924X |
| DOI: | 10.1093/oxfordjournals.jbchem.a022433 |
| Popis: | Porcine cardiac myosin monomers in equilibrium with filaments under physiological conditions were observed to have two conformations, extended and folded forms, upon electron microscopy and gel filtration HPLC. The conformational state was independent of ATP and the phosphorylation of regulatory light chain. The folded monomers of cardiac myosin were mainly in an open conformation with only one bend in the tail, and may not trap the hydrolysis products of ATP, as assessed by single turnover experiments. These properties are similar to those of the folded monomers of rabbit skeletal myosin [Katoh, T., Konishi, K., and Yazawa, M. (1998) J. Biol. Chem. 273, 11436-11439]. The conformational states of skeletal and cardiac myosin monomers were not affected by pH between 7.0 and 8.5. Although significant disassembly of filaments and thus an increase in the monomer concentration were observed with an increase in pH. The results indicate that the pH-dependent change in filament assembly is due to a shift of equilibrium between the filaments and extended monomers toward filament disassembly. The Mg2+-ATPase activity of these myosin monomers decreased with a decrease in the salt concentration below approximately 0.1 M, suggestive of the formation of a closed conformation similar to the conformation of 10S smooth myosin. The results suggest that the conformational change from the extended to the folded form is a common property of various myosin IIs. |
| Databáze: | OpenAIRE |
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