AF007: EF hand domain
- Pfam domains
- PF00036: EF hand
- PF01023: S-100/ICaBP type calcium binding domain
- PF12763: Cytoskeletal-regulatory complex EF hand
A wide range of calcium-binding proteins share a conserved domain cosisting of a 12 residue calcium-binding loop flanked on both sides by α-helices of 12 residues in length. The biological functions of these proteins can be divided into two classes: signaling and calcium buffering or transport. Signaling proteins such as calmodulin and troponin C undergo a conformational change upon calcium binding.
Several groups of allergens were found within this family.
- Parvalbumins: Parvalbumins are 12 kDa proteins containing two EF hand domains. They are found in fast-twitch muscle fibers of vertebrates and bind Ca2+ during muscle relaxation . Parvalbumins from fishes and amphibians are major food allergens eliciting IgE reponses in most fish-allergic individuals . Parvalbumins from higher vertebrates have not been shown to bind human IgE.
- Polcalcins: Polcalcins are 9 kDa calcium-binding pollen proteins of unknown biological function . While regular polcalcins contain two EF hand domains, several polcalcin-related allergens with three or four EF hand domains were described. Polcalcins were shown to be minor albeit highly cross-reactive allergens identified in pollen from diverse plant families .
- Troponin C: Troponin C is a muscle protein that binds to the thin filaments and initiates muscle contraction upon binding of Ca2+ . Allergens from this family were found in cockroaches (group 6 allergens) .
- Sarcoplasmic calcium binding proteins: The invertebrate muscle proteins were proposed to exert a calcium buffering function similar to that of parvalbumins in vertebrate muscle . Members of this family were described as allergens in crustaceans .
The IgE binding capacity of some EF hand-containing allergens was shown to be calcium-dependend.
Calcium ion in skeletal muscle: its crucial role for muscle function, plasticity, and disease.
Physiol Rev 2000, 80, 1215-65. [PubMed]
Fish and shellfish allergy.
Curr Allergy Asthma Rep 2005, 5, 74-9. [PubMed]
Expression of Bra r 1 gene in transgenic tobacco and Bra r 1 promoter activity in pollen of various plant species.
Plant Cell Physiol 2000, 41, 757-66. [PubMed]
A comparative analysis of the cross-reactivity in the polcalcin family including Syr v 3, a new member from lilac pollen.
Allergy 2006, 61, 477-84. [PubMed]
Bla g 6: a troponin C allergen from Blattella germanica with IgE binding calcium dependence.
J Allergy Clin Immunol 2006, 117, 1389-95. [PubMed]
Molecular characterization of the sarcoplasmic calcium-binding protein (SCP) from crayfish Procambarus clarkii.
Comp Biochem Physiol B Biochem Mol Biol 2006, 144, 478-87. [PubMed]
Sarcoplasmic calcium-binding protein is an EF-hand-type protein identified as a new shrimp allergen.
J Allergy Clin Immunol 2009, 124, 114-20. [PubMed]
If you have updates or corrections for this entry, please contact the