Apo and InsP3-bound crystal structures of the ligand-binding domain of an InsP3 receptor

Inositol 1,4,5-triphosphate (InsP3) receptors are ligand-activated calcium channels in the endoplasmic reticulum membrane, and they are responsible for the cytoplasmic Ca2+ efflux that triggers many cellular processes. The crystal structures of the ligand-binding domain of rat type I InsP3R in its apo and ligand-bound form reveal the conformational changes that ultimately control channel gating.