Cytoplasmic Ca2+ is a primary determinant for myosin phosphorylation in smooth muscle cells

D. A. Taylor, B. F. Bowman, J. T. Stull

Research output: Contribution to journalArticle

44 Scopus citations

Abstract

Initiation of smooth muscle contraction is associated with Ca2+/calmodulin activation of myosin light chain kinase which catalyzes the phosphorylation of the 20-kDa light chain of myosin. In tracheal smooth muscle cells in culture, the extent of myosin light chain phosphorylation is less than 10% at basal cytosolic free Ca2+ concentrations of 150 nM. Stimulation of these cells with serotonin, histamine, carbachol, or the Ca2+ ionophore, ionomycin, increases free cytosolic Ca2+ concentrations and the extent of myosin light chain phosphorylation. Light chain phosphorylation reaches a maximal value of 67% at Ca2+ concentrations below 1 μM. The relationship between the extent of light chain phosphorylation and cytosolic free Ca2+ concentration is apparently independent of the source of free intracellular Ca2+ or the agent used to stimulate the cells and is not altered by pre-exposure of the contractile apparatus to high concentrations of free Ca2+. Pretreatment of cells with 8-bromo-cyclic GMP or forskolin decreases free cytosolic Ca2+ concentrations and the extent of myosin light chain phosphorylation in response to histamine or ionomycin. Pretreatment with 8-bromo-cyclic GMP also decreases the maximal extent of light chain phosphorylation. These results indicate that cytosolic free Ca2+ concentration, per se, is a primary determinant for myosin light chain phosphorylation in tracheal smooth muscle cells.

Original languageEnglish (US)
Pages (from-to)6207-6213
Number of pages7
JournalJournal of Biological Chemistry
Volume264
Issue number11
StatePublished - Jan 1 1989

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Fingerprint Dive into the research topics of 'Cytoplasmic Ca<sup>2+</sup> is a primary determinant for myosin phosphorylation in smooth muscle cells'. Together they form a unique fingerprint.

  • Cite this