inositoltrifosfato

Inositol trisphosphate, often abbreviated as IP3, is a crucial second messenger molecule in intracellular signal transduction. It is a phosphorylated derivative of inositol, a cyclic alcohol. IP3 is generated when a G protein-coupled receptor, activated by an extracellular signal, triggers the enzyme phospholipase C. Phospholipase C then cleaves phosphatidylinositol 4,5-bisphosphate (PIP2), a lipid component of the cell membrane, into diacylglycerol (DAG) and IP3. Once released into the cytoplasm, IP3 diffuses to the endoplasmic reticulum and binds to specific IP3 receptors on its membrane. This binding causes the release of stored calcium ions (Ca2+) from the endoplasmic reticulum into the cytosol. The increase in intracellular calcium concentration then mediates a wide range of cellular responses, including muscle contraction, neurotransmitter release, and metabolic regulation. IP3's role as a calcium-releasing agent makes it a central player in numerous signaling pathways essential for cell function and communication. Its rapid production and degradation allow for transient and localized signaling events.