EF hands are helix-loop-helix binding motifs involved in the regulation of many cellular processes. EF hands usually bind to Ca2+ ions which causes a major conformational change that allows the protein to interact with its designated targets. This domain corresponds to an EF hand which has partially or entirely lost its calcium-binding properties. The calcium insensitive EF hand is still able to mediate protein-protein recognition [1].

1: Ca2+-independent binding of an EF-hand domain to a novel motif in the alpha-actinin-titin complex. Atkinson RA, Joseph C, Kelly G, Muskett FW, Frenkiel TA, Nietlispach D, Pastore A; Nat Struct Biol. 2001;8:853-857. PMID:11573089