Inositol Triphosphate Receptor (None)

The inositol triphosphate receptor (IP3R) is a ligand-gated calcium channel primarily located on the endoplasmic reticulum membrane. Upon binding of inositol 1,4,5-trisphosphate (IP3), it mediates the release of Ca2+ from intracellular stores into the cytosol, thereby regulating numerous cellular processes including cell migration, cell division, smooth muscle contraction, and neuronal signaling. It is a tetrameric channel with each subunit containing an IP3-binding domain and six transmembrane helices forming the ion-conducting pore. Activation requires both IP3 binding and local increases in cytosolic Ca2+.

Other names

Inositol trisphosphate receptorInsP₃RITPR

IP3 binding induces Ca2+ release from the endoplasmic reticulum.