Calcium-induced conformational transition revealed by the solution structure of apo calmodulin

Nat Struct Biol. 1995 Sep;2(9):758-67. doi: 10.1038/nsb0995-758.


The solution structure of Ca(2+)-free calmodulin has been determined by NMR spectroscopy, and is compared to the previously reported structure of the Ca(2+)-saturated form. The removal of Ca2+ causes the interhelical angles of four EF-hand motifs to increase by 36 degrees-44 degrees. This leads to major changes in surface properties, including the closure of the deep hydrophobic cavity essential for target protein recognition. Concerted movements of helices A and D with respect to B and C, and of helices E and H with respect to F and G are likely responsible for the cooperative Ca(2+)-binding property observed between two adjacent EF-hand sites in the amino- and carboxy-terminal domains.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / chemistry
  • Calcium / metabolism*
  • Calmodulin / chemistry*
  • Calmodulin / metabolism*
  • Crystallization
  • Crystallography, X-Ray
  • Magnetic Resonance Spectroscopy
  • Methionine / chemistry
  • Protein Conformation
  • Solutions


  • Calmodulin
  • Solutions
  • Methionine
  • Calcium