Phosphorylation-dependent activated tension in skinned gizzard muscle fibers in the absence of Ca2+.

M. P. Walsh, R. Bridenbaugh, D. J. Hartshorne, W. G. Kerrick

Research output: Contribution to journalArticle

47 Scopus citations

Abstract

A Ca2+-insensitive myosin light chain kinase was prepared and used in experiments with skinned gizzard fibers. In the absence of Ca2+, this kinase activated isometric force development. The force development was associated with phosphorylation of the 20,000-dalton myosin light chains and addition of Ca2+ did not activate the fibers further. Pretreatment of the fibers with Ca2+-insensitive myosin light chain kinase and adenosine 5'-O-(3-thiotriphosphate) in the absence of Ca2+ caused thiophosphorylation of the light chains and, on the addition of ATP, an activation of isometric tension was observed. The subsequent addition of Ca2+ did not increase force development. A comparison of Ca2+-activated tension in the skinned gizzard muscle fibers with Ca2+-insensitive myosin light chain kinase-activated tension suggests that the phosphorylation of the myosin light chains is the dominant factor in the development of tension in smooth muscle.

Original languageEnglish (US)
Pages (from-to)5987-5990
Number of pages4
JournalJournal of Biological Chemistry
Volume257
Issue number11
StatePublished - Jun 10 1982
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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