Regulation of the smooth muscle contractile phenotype by nonmuscle myosin

Ozgur Ogut, Samantha L. Yuen, Frank V. Brozovich

Research output: Contribution to journalReview articlepeer-review

18 Scopus citations


The contractile phenotype of a smooth muscle can broadly be classified as phasic or tonic. Following activation, phasic smooth muscle exhibits an initial period of rapid force activation, following which force falls to a lower steady state level. In contrast, force generated by tonic smooth muscle rises slowly to a sustained steady state. The differences in contractile patterns cannot be explained by the time course of either the Ca2+ transient or phosphorylation of the 20-kDa regulatory myosin light chain (MLC20). Therefore, a molecular marker that defines tonic and phasic smooth muscle contractile properties remains elusive. Further, smooth muscle can maintain force at low levels of MLC20 phosphorylation; often referred to as the latch state. The mechanism for the latch state is unknown and has been hypothesized to be due to a number of mechanisms including the formation of slowly cycling dephosphorylated or latch cross-bridges (Hai and Murphy, Am J Physiol 253:H1365-H1371, 1988). This review will focus evidence suggesting that nonmuscle myosin IIB (NMIIB) are the latch cross-bridges in smooth muscle and NMIIB content could define the tonic contractile phenotype.

Original languageEnglish (US)
Pages (from-to)409-414
Number of pages6
JournalJournal of Muscle Research and Cell Motility
Issue number7-8
StatePublished - Oct 2007


  • Contractility
  • Cross-bridge
  • Force maintenance
  • Latch state

ASJC Scopus subject areas

  • Biochemistry
  • Physiology
  • Cell Biology


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