Quantitative measurements of Ca2+/calmodulin binding and activation of myosin light chain kinase in cells

Ramaz Geguchadze, Gang Zhi, Kim S. Lau, Eiji Isotani, Anthony Persechini, Kristine E. Kamm, James T. Stull

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


Myosin II regulatory light chain (RLC) phosphorylation by Ca 2+/calmodulin (CaM)-dependent myosin light chain kinase (MLCK) is implicated in many cellular actin cytoskeletal functions. We examined MLCK activation quantitatively with a fluorescent biosensor MLCK where Ca 2+-dependent increases in kinase activity were coincident with decreases in fluorescence resonance energy transfer (FRET) in vitro. In cells stably transfected with CaM sensor MLCK, increasing [Ca2+] i increased MLCK activation and RLC phosphorylation coincidently. There was no evidence for CaM binding but not activating MLCK at low [Ca 2+]i. At saturating [Ca2+]i MLCK was not fully activated probably due to limited availability of cellular Ca 2+/CaM.

Original languageEnglish (US)
Pages (from-to)121-124
Number of pages4
JournalFEBS Letters
Issue number1-3
StatePublished - Jan 16 2004


  • Calcium
  • Calmodulin
  • Fluorescence resonance energy transfer
  • Myosin light chain kinase
  • Phosphorylation

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology


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