Activation mechanism of rabbit skeletal muscle myosin light chain kinase 5′-p-Fluorosulfonylbenzoyl adenosine as a probe of the MgATP-binding site of the calmodulin-bound and calmodulin-free enzyme

Peter J. Kennelly, Joel C. Colburn, James Lorenzen, Arthur M. Edelman, James T. Stull, Edwin G. Krebs

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5 Scopus citations


5′-p-Fluorosulfonylbenzoyl adenosine (FSBA), an ATP-like affinity labelling reagent, reacted with rabbit skeletal muscle myosin light chain kinase (skMLCK) and its calmodulin complex in a site-specific manner. Reaction was dependent upon the presence of the adenosine moiety of FSBA, saturated with increasing FSBA, was inhibited by MgATP, and was accompanied by stoichiometric incorporation of [14C]FSBA. The kinetic constants describing the reaction were similar for skMLCK and its calmodulin complex: k3= -0.040 min-1 and -0.038 mint-1, and Ki=0.18 mM and 0.40 mM, respectively. It is concluded that the MgATP-binding site on skMLCK remains accessible at all times and maintains a near constant conformation.

Original languageEnglish (US)
Pages (from-to)217-220
Number of pages4
JournalFEBS Letters
Issue number1-2
Publication statusPublished - Jul 29 1991



  • 5′-p-Fluorosulfonylbenzoyl adenosine
  • Autoinhibition
  • Calmodulin
  • Myosin light chain kinase
  • Pseudosubstrate

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

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