Factors influencing interaction of phosphorylated and dephosphorylated myosin with actin

Dariusz Stȩpkowski, Danuta Szczȩsna, Michł Wrotek, Irena Ka̧kol

Research output: Contribution to journalArticle

36 Scopus citations

Abstract

The influence of various factors on the interaction of phosphorylated and dephosphorylated myosin with action was examined. It was found that the difference between the values of specific activity of the two myosin forms of actin-stimulated Mg2+-ATPase is affected by changes in KCl, MgATP and acting concentration. The effect of increased pH on the differences in the rate of ATP hydrolysis by actomyosin containing phosphorylated myosin as compared with that of the dephosphorylated one, observed in the presence of EGTA, is abolished by addition of Ca2+. Tropomyosin strongly inhibits the actin-stimulated Mg2+-ATPase of phosphorylated myosin (by about 60%). The tropomyosin-troponin complex and native tropomyosin lowered the rate of ATP hydrolysis by actomyosin containing both phosphorylated and dephosphorylated myosin by about of 60% of the value obtained in the absence of those proteins. These results indicate that the change of negative charge on the myosin head due to phosphorylation and dephosphorylation of myosin light chains modulates the actin-myosin interaction at different steps of the ATP hydrolysis cycle. Phosphorylation of myosin seems to be a factor decreasing the rate of ATP hydrolysis by actomyosin under physiological conditions.

Original languageEnglish (US)
Pages (from-to)321-329
Number of pages9
JournalBiochimica et Biophysica Acta (BBA)/Protein Structure and Molecular
Volume831
Issue number3
DOIs
StatePublished - Oct 18 1985
Externally publishedYes

Keywords

  • Actin
  • ATP hydrolysis
  • Myosin
  • Protein phosphorylation
  • Troponin

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology
  • Structural Biology

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