Relationship between paxillin and myosin phosphorylation during muscarinic stimulation of smooth muscle

Dolly Mehta, Zhonglin Wang, Ming Fang Wu, Susan J. Gunst

Research output: Contribution to journalArticle

24 Scopus citations


The tyrosine phosphorylation of paxillin increases in association with force development during tracheal smooth muscle contraction, suggesting that paxillin plays a role in the contractile activation of smooth muscle [Z. L. Wang, F. M. Pavalko, and S. J. Gunst. Am. J. Physiol. 271 (Cell Physiol. 40): C1594-C1602, 1996]. We compared the Ca2+ sensitivity of the tyrosine phosphorylation of paxillin and myosin light chain (MLC) phosphorylation in tracheal muscle and evaluated whether MLC phosphorylation is necessary to induce paxillin phosphorylation. Ca2+-depleted muscle strips were stimulated with 10-7-10-4 M acetylcholine (ACh) in 0, 0.05, 0.1, or 0.5 mM extracellular Ca2+. In the absence of extracellular Ca2+, 10-4 M ACh induced a maximal increase in paxillin phosphorylation without increasing MLC phosphorylation or force. Increases in extracellular Ca2+ concentration did not further increase paxillin phosphorylation. However, during stimulation with 10-6 M ACh, paxillin phosphorylation increased with increases in extracellular Ca2+ concentration. We conclude that the tyrosine phosphorylation of paxillin can be stimulated by signaling pathways that do not depend on Ca2+ mobilization and that the activation of contractile proteins is not required to elicit paxillin phosphorylation.

Original languageEnglish (US)
Pages (from-to)C741-C747
JournalAmerican Journal of Physiology - Cell Physiology
Issue number3 43-3
StatePublished - Mar 1998


  • Cytoskeleton
  • Focal adhesion proteins
  • Myosin light chain phosphorylation
  • Smooth muscle contraction

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology
  • Physiology (medical)

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