Structural aspects of EF-hand containing calcium buffers, sensors, and S100 family

Abstract

The EF-hand motif is one of the common calcium binding motifs, and the protein family containing this motif plays anessential role in the regulating all aspects of cellular processes. The EF-hand motif is a helix-loop-helix structure and thecanonical EF-hand chelates Ca2+ by seven ligands in the loop with pentagonal bipyramid geometry. Many high-resolutionstructures of EF-hand containing calcium binding proteins (CaBPS), as well as the complex with target proteins, have beenidentified. They exhibit a various loop composition and structure and they affect a great diversity of target interaction andfunctions. In this review, structural details of the EF-hand motif are discussed to understand the Ca2+ binding mechanism,Ca2+-induced conformational change in EF-hand CaBPS, and the diversity of their complex with their target molecules.