Light-chain phosphorylation controls the conformation of vertebrate non-muscle and smooth muscle myosin molecules
Open Access
- 1 March 1983
- journal article
- letter
- Published by Springer Science and Business Media LLC in Nature
- Vol. 302 (5907), 436-439
- https://doi.org/10.1038/302436a0
Abstract
Phosphorylation of the 20,000-molecular weight (Mr) light chains of vertebrate non-muscle (thymus) and smooth muscle (gizzard) myosins regulates the assembly of these myosins into filaments in vitro1,2. At physiological ionic strength and pH, nonphosphorylated smooth muscle and non-muscle myosin filaments are disassembled by stoichiometric levels of MgATP, forming species having sedimentation coefficients of ∼11S (range 10–12S1,3,4; myosin monomers in high salt sediment at 6S). When the 20,000 (20K)-Mr light chains on these 11S myosin species are phosphorylated by the light-chain kinase/calmodulin–Ca2+ complex, the inhibitory effect of the light chains on filament formation is removed and the myosins reassemble into filaments which are stable in MgATP1,2,5,6. It was originally suggested that the 11S myosin species was a dimer1,3, previously suggested as a building block for smooth muscle and non-muscle myosin filaments7,8. It has since been shown, however, that 11S smooth muscle myosin is monomeric4,9 and has a folded conformation4,10 rather than the extended shape characteristic of monomeric myosin in high salt11,12. Here we show that 11S non-muscle myosin is also folded and that phosphorylation of the 20K-Mr light chains of both vertebrate non-muscle (thymus) and vertebrate smooth muscle (gizzard) myosins causes these folded 11S molecules to unfold into the conventional extended monomeric form, which is able to assemble into filaments.Keywords
This publication has 20 references indexed in Scilit:
- A bent monomeric conformation of myosin from smooth muscle.Proceedings of the National Academy of Sciences of the United States of America, 1982
- Electron Microscopic Studies of Myosin Molecules from Chicken Gizzard Muscle I: The Formation of the Intramolecular Loop in the Myosin Tail1The Journal of Biochemistry, 1982
- Regulation of Myosin-filament Assembly by Light-chain PhosphorylationCold Spring Harbor Symposia on Quantitative Biology, 1982
- The role of myosin light chains in regulating actin-myosin interactionBiochimie, 1981
- Regulation of non-muscle myosin assembly by calmodulin-dependent light chain kinaseNature, 1980
- Structure and Function of Chicken Gizzard Myosin1The Journal of Biochemistry, 1978
- Mode of filament assembly of myosins from muscle and nonmuscle cellsJournal of Ultrastructure Research, 1978
- Shape and flexibility of the myosin moleculeJournal of Molecular Biology, 1978
- Assembly of smooth muscle myosin into side-polar filaments.The Journal of cell biology, 1977
- Substructure of the myosin molecule: I. Subfragments of myosin by enzymic degradationJournal of Molecular Biology, 1969