inositol trisphosphate (IP3)

Inositol trisphosphate (IP3) is a signaling molecule inside cells that helps transmit signals from the outside to the inside. When a receptor on the cell surface detects a signal, it activates a series of reactions that produce IP3. IP3 then binds to receptors on the endoplasmic reticulum, a cell structure that stores calcium. This causes calcium to be released into the cell's interior, triggering various responses like muscle contraction, secretion, or other activities. IP3 thus acts as a messenger, translating external signals into internal actions that enable the cell to respond appropriately.