EF-hand proteins

EF-hand proteins are homologous; they have all evolved from a common precursor. They contain from two to twelve copies of the EF-hand domain. The EF-hand is about thirty amino acids long and consists of an alpha-helix (E), loop, and second alpha-helix (F). Usually a Ca2+ ion is bound in the loop under physiological conditions; however, 30% of all known EF-hands do not bind calcium. With only a few exceptions all EF-hand containing proteins are found in the cytosols of eukaryotic cells. Most of them function as transducers of infor mation. In so called quiescent cells the concentration of the free Ca2+ ion is about 10-7.2 M; following a stimulus to the cell [Ca2+] rises to ~ 10-5.8 M. Many EF-hand proteins are calcium modulated. In a quiescent cell they are in the apo or in the magnesium form; following stimulation they are in the calcium form. These calcium signals are tuned by complex spatial and temporal distributions, as well as by differing affinities and binding rates of calcium modulated proteins. We summarize the characteristics of the 66 known subfamilies of EF-hand proteins in old Database and 156 subfamilies of EF-hand proteins in the updated Database.


  1. Characteristics of EF-hands and of EF-hand Proteins
    1. Functions of EF-hand Proteins
    2. EF-hands and Ca2+ Binding
    3. Pairs of EF-hands
    4. Congruence within and among EF-hand Subfamilies
  2. Subfamilies of EF-hand Proteins (Old EF-hand Database)
  3. Calssifications of subfamilies (Updated EF-hand protein Database, 2016)
  4. Perspectives
  5. References

EF-hand Database

Hiroshi Kawasaki
Graduate School of Medical Life Science,
Yokohama City University,
Suehiro-cho 1-7-29, Tsurumi-ku, Yokohama 230-0045, Japan

Robert H. Kretsinger
Department of Biology, University of Virginia,
Charlottesville, VA, 22901, USA