 EF-Hand Domain | |
|
|
Structure:
 The basic EF-hand consists of two perpendicular 10 to 12 residue alpha helices with a 12-residue loop region between, forming a single calcium-binding site (helix-loop-helix). Calcium ions interact with residues contained within the loop region. Each of the 12 residues in the loop region is important for calcium coordination. In EF-hand motifs, residues 1, 3, 5, 7, 9, and 12 of the conserved loop region provide oxygen ligands to the calcium ion necessary for its binding. In most EF-hand proteins the residue at position 12 is a glutamate. The glutamate contributes both its side-chan oxygens for calcium coordination. Variations in calcium binding affinity for different EF-hand proteins is due to the amino-acid composition in the 1, 3, 5, 7, and 9 positions.
Structure Reference:
PDB: 2PMY.
| |
|
Domain binding and function:
The EF-hand motif contains approximately 40 residues and is involved in binding intracellular calcium. EF-hand domains are often found in single or multiple pairs, giving rise to various structural/functional variations in proteins containing EF-hand motifs. Proteins containing EF-hands can be grouped into two functional categories - regulatory or structural. Binding of calcium to regulatory EF hand domain-containing proteins induces a conformational change, which is transmitted to their target proteins, often catalyzing enzymatic reactions. In contrast, binding of calcium to structural EF-hand domain-containing proteins does not induce a significant conformational change. Structural EF-hand domains seem to play a role in buffering intracellular calcium levels.
| |
|
Examples of Proteins:
| EF-h domain protein |
|
Binding partner |
function |
| Calmodulin |  |
Ca2+ |
Regulatory proteins |
| S-100 | |
Ca2+ |
Regulatory proteins |
| recoverin | |
Ca2+ |
Regulatory proteins |
| calbindin | |
Ca2+ |
Structural proteins |
| parvalbumin | |
Ca2+ |
Structural proteins |
|
|
|
|
| |
|
Referenced in part on Cell Signaling Technology Website, Reference Section on Protein Domains. We gratefully acknowledge the following contributors:
Piers Nash1, Dan Lin3, Kathleen Binns2, Clark Wells2, Rob Ingham2, Terry Kubiseski2, Bernard Liu1, Matt Smith2,3, Ivan Blasutig2,3, Maria Sierra1, Caesar Lim2,3, Michael Arc1, Jim Fawcett2 and Tony Pawson2,3.
1. Ben May Institute for Cancer Research, The University of Chicago, Chicago, Illinois, 60637, USA
2. Program in Molecular Biology and Cancer, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, M5G 1X5, Canada
3. Department of Molecular and Medical Genetics, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
| |
|
