Gain of function mutations for yeast calmodulin and calcium dependent regulation of protein kinase activity

Thomas J. Lukas, Mark Collinge, Jacques Haiech, D. Martin Watterson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Yeast calmodulin binds only three calcium ions in the presence of millimolar concentrations of magnesium due to a defective calcium-binding sequence in its carboxyl terminal domain. Yeast calmodulin's diminished calcium-binding activity can be restored to that of other calmodulins by the use of site-directed mutagenesis to substitute its fourth calcium-binding domain with that of a vertebrate calmodulin sequence. However, the repair of yeast calmodulin's calcium-binding activity is not sufficient to repair quantitatively yeast calmodulin's defective protein kinase activator activity. Yeast calmodulin's activator activity with smooth muscle and skeletal muscle myosin light chain kinases and brain calmodulin-dependent protein kinase II can be progressively repaired by additional substitutions of vertebrate calmodulin sequences, provided that the four calcium-binding sites remain intact. An unexpected result obtained during the course of these studies was the observation that myosin light chain kinases from smooth and skeletal muscle tissues can respond differently to mutations in calmodulin. These and previous results indicate that the binding of four calcium ions by calmodulin is necessary but not sufficient to bring about quantitative activation of protein kinases, and are consistent with the conformational selection/restriction model of the dynamic equilibrium among calcium, calmodulin and each calmodulin regulated enzyme.

Original languageEnglish (US)
Pages (from-to)341-347
Number of pages7
JournalBBA - Molecular Cell Research
Issue number3
StatePublished - Sep 29 1994


  • Calcium binding
  • Calmodulin
  • Molecular dynamics
  • Mutagenesis
  • Protein engineering
  • Protein kinase

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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