InterPro domain: IPR002048

Many calcium-binding proteins belong to the same evolutionary family and share a type of calcium-binding domain known as the EF-hand. This type of domain consists of a twelve residue loop flanked on both sides by a twelve residue alpha-helical domain. In an EF-hand loop the calcium ion is coordinated in a pentagonal bipyramidal configuration. The six residues involved in the binding are in positions 1, 3, 5, 7, 9 and 12; these residues are denoted by X, Y, Z, -Y, -X and -Z. The invariant Glu or Asp at position 12 provides two oxygens for liganding Ca (bidentate ligand). Ca2 binding induces a conformational change in the EF-hand motif, leading to the activation or inactivation of target proteins. EF-hands tend to occur in pairs or higher copy numbers [ 1 , 2 , 3 , 4 , 5 ].

1. EF-hands embrace. Trends Biochem. Sci. 4, 514-6
2. Calcium binding and conformational response in EF-hand proteins. Nat. Struct. Biol. 21, 14-7
3. Calcium-binding proteins 1: EF-hands. Nat. Struct. Biol. 2, 297-490
4. Signal transduction versus buffering activity in Ca(2+)-binding proteins. Proteins 1, 239-45
5. Diversity of conformational states and changes within the EF-hand protein superfamily. null 37, 499-507