Regulation of the actin-activated MgATPase activity of Acanthamoeba myosin II by phosphorylation of serine 639 in motor domain loop 2.

ABSTRACT: It had been proposed previously that only filamentous forms of Acanthamoeba myosin II have actin-activated MgATPase activity and that this activity is inhibited by phosphorylation of up to four serine residues in a repeating sequence in the C-terminal nonhelical tailpiece of the two heavy chains. We have reinvestigated these issues using recombinant WT and mutant myosins. Contrary to the earlier proposal, we show that two nonfilamentous forms of Acanthamoeba myosin II, heavy meromyosin and myosin subfragment 1, have actin-activated MgATPase that is down-regulated by phosphorylation. By mass spectroscopy, we identified five serines in the heavy chains that can be phosphorylated by a partially purified kinase preparation in vitro and also are phosphorylated in endogenous myosin isolated from

SUBMITTER: Liu X 

PROVIDER: S-EPMC3538207 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature