Viewing Ca2+-binding sites in the inositol trisphosphate receptor

Ca²⁺ is a major ligand of the inositol 1,4,5-trisphosphate receptor (IP₃R) Ca²⁺-release channel. Fan et al. [1] recently solved additional cryo-electron microscopy (cryo-EM) structures of the IP₃R in different ligand-binding states, revealing new Ca²⁺ binding sites.