Ca2+-independent binding of an EF-hand domain to a novel motif in the alpha-actinin-titin complex

Nat Struct Biol. 2001 Oct;8(10):853-7. doi: 10.1038/nsb1001-853.


The interaction between alpha-actinin and titin, two modular muscle proteins, is essential for sarcomere assembly. We have solved the solution structure of a complex between the calcium-insensitive C-terminal EF-hand domain of alpha-actinin-2 and the seventh Z-repeat of titin. The structure of the complex is in a semi-open conformation and closely resembles that of myosin light chains in their complexes with heavy chain IQ motifs. However, no IQ motif is present in the Z-repeat, suggesting that the semi-open conformation is a general structural solution for calcium-independent recognition of EF-hand domains.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actinin / chemistry
  • Actinin / metabolism*
  • Amino Acid Motifs
  • Amino Acid Sequence
  • Binding Sites
  • Calcium / metabolism*
  • Calcium-Binding Proteins / chemistry
  • Calcium-Binding Proteins / metabolism*
  • Connectin
  • Models, Molecular
  • Molecular Sequence Data
  • Muscle Proteins / chemistry
  • Muscle Proteins / metabolism*
  • Nuclear Magnetic Resonance, Biomolecular
  • Protein Conformation
  • Protein Kinases / chemistry
  • Protein Kinases / metabolism*
  • Sequence Homology, Amino Acid


  • Calcium-Binding Proteins
  • Connectin
  • Muscle Proteins
  • Actinin
  • Protein Kinases
  • Calcium

Associated data

  • PDB/1H8B