EF-hand-like domain <p>This domain consists of a duplication of two EF-hand units, where each unit is composed of two helices connected by a twelve-residue calcium-binding loop. The calcium ion in the EF-hand loop is coordinated in a pentagonal bipyramidal configuration. Many calcium-binding proteins contain an EF-hand type calcium-binding domain [<cite idref="PUB00014021"/>, <cite idref="PUB00014022"/>]. These include: calbindin D9K, S100 proteins such as calcyclin, polcalcin phl p 7 (a calcium-binding pollen allergen), osteonectin, parvalbumin, calmodulin [<cite idref="PUB00014032"/>] family of proteins (troponin C, caltractin, cdc4p, myosin essential chain, calcineurin, recoverin, neurocalcin), plasmodial-specific CaII-binding protein Cbp40, penta-EF-Hand proteins [<cite idref="PUB00014023"/>] (sorcin, grancalcin, calpain), as well as multidomain proteins such as phosphoinositide-specific phospholipase C, dystrophin, Cb1 and alpha-actinin. The fold consists of four helices and an open array of two hairpins.</p>