Stimulation of Acanthamoeba actomyosin ATPase activity by myosin-II polymerization.

Journal Article

Phosphorylation of the regulatory light chains of vertebrate smooth muscle or cytoplasmic myosins alters the structure of myosin monomers, favours myosin filament formation and stimulates the actin-activated Mg2+-ATPase of myosin. Similarly, in Dictyostelium and Acanthamoeba phosphorylation of the myosin heavy chains exhibits 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.

Full Text

Duke Authors

Cited Authors

  • Kiehart, DP; Pollard, TD

Published Date

  • April 26, 1984

Published In

Volume / Issue

  • 308 / 5962

Start / End Page

  • 864 - 866

PubMed ID

  • 21510101

International Standard Serial Number (ISSN)

  • 0028-0836

Language

  • eng

Conference Location

  • England