IP₃R function in cells of the immune system

Calcium ions regulate almost all cellular processes. Inositol 1,4,5-trisphosphate receptors (IP₃Rs) are ubiquitous calcium channels which mediate calcium release primarily from endoplasmic reticulum stores. IP₃Rs are activated by the soluble second messenger inositol 1,4,5-trisphosphate (IP₃), which is produced in response to various stimuli by the action of phospholipase C enzymes. Very soon after the discovery that IP₃ is a calcium mobilizing second messenger, it was found that T-cell receptor signaling is dependent upon IP₃R activity. It is now known that cell signaling throughout the immune system is dependent upon IP₃R-dependent calcium release for many critical processes, including cellular activation, proliferation, and death. This channel plays a critical role in orchestrating the immune response in health and disease and thus offers potential as a therapeutic target in immune-related disorders.