Fig. 1.

Model for the activation mechanism of store-operated Ca²⁺ channels (SOCCs)

SOCCs are a family of Ca²⁺ permeable ion channels expressed by most cells. The signal for the activation of these ion channels is a decrease in the Ca²⁺ concentration in the endoplasmic reticulum (ER). Stimulation of diverse plasma membrane (PM) receptors converges on the activation of phosphatidylinositol (4,5)-bisphosphate [PtdIns(4,5)P₂] hydrolysis, which results in the generation of diacylglycerol (DAG) and inositol (1,4,5)-trisphosphate [Ins(1,4,5)P₃], and the subsequent activation of Ca²⁺ release from the ER via Ins(1,4,5)P₃ receptor and Ca²⁺ influx across the PM. Depletion of ER Ca²⁺ activates PM-localized Ca²⁺ influx channels known as SOCCs