Stimulation of Acanthamoeba actomyosin ATPase activity by myosin-II polymerization
- 1 April 1984
- journal article
- letter
- Published by Springer Nature in Nature
- Vol. 308 (5962), 864-866
- https://doi.org/10.1038/308864a0
Abstract
Phosphorylation of the regulatory light chains of vertebrate smooth muscle or cytoplasmic myosins alters the structure of myosin monomers1–4, favours myosin filament formation5,6 and stimulates the actin-activated Mg2+-ATPase of myosin (for reviews see refs 7–9). Similarly, in Dictyostelium10 and Acanthamoeba11–13 phosphorylation of the myosin heavy chains inhibits both polymerization and actin-activated Mg2+-ATPase. Unfortunately, the relationships between phosphorylation, myosin assembly and activation of ATP hydrolysis are not fully understood in any of these systems, as there has been no way of varying the extent of polymerization of intact myosin without changing solution conditions or the level of myosin phosphorylation, parameters that may have independent effects on ATPase activity. Taking an entirely new approach, we have used monoclonal antibodies against the tail of Acanthamoeba myosin-II that cause filament disassembly to show that myosin polymerization itself stimulates actomyosin ATPase activity. With a fixed level of myosin-II phosphorylation and constant solution conditions, depolymerization of myosin-II filaments by antibodies causes a concomitant loss of actin-activated ATPase activity.Keywords
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