Inositol 1,4,5 trisphosphate
A small molecule involved in intracellular signalling. It is produced when the inositol phospholipid signalling pathway is activated and is one of the main factors in the release of Ca2+ ions from the endoplasmic reticulum [1].
Inositol 1,4,5-trisphosphate (IP3) is a common secondary messenger used in signal transduction. When phosphatidylinositol 4,5-bisphosphate (PIP2) is hydrolysed by phospholipase C it produces IP3 and diacylglycerol (DAG) [2]. IP3 is soluble so can diffuse through the cell to its IP3 receptor (InsP3R) on the endoplasmic reticulum or sarcoplasmic reticulum. IP3 receptor acts as a calcium ion channel, so once IP3 is bound it allows the movement of Ca2+ ions from the endoplasmic reticulum into the cell down their concentration gradient. This influx of calcium causes a calcium induced calcium response (CICR) which along with IP3 helps to activate many more InsP3R [3], leading to a huge amplification of Ca2+ in the cell.
IP3 (Inositol 1,4,5-trisphosphate) is a cleavage product of phosphatidylinositol 4,5-bisphosphate (PIP2). PIP2 is a phospholipid molecule cleaved into inositol 1,4,5-trisphosphate and diacylglycerol (DAG) by phospholipase C after hormone binding to the receptor. Inositol 1,4,5-trisphosphate binds to IP3receptor which results to the release of calcium from the calcium pumps.
Also see cell and membrane transport
References
- ↑ Alberts B., Johnson A., Lewis J., Raff M., Roberts K., Walter P., (2008), Molecular Biology of the Cell, 5th Edition, New York: Garland Science
- ↑ Alberts et al, 2008, Mollecular biology of the Cell, 5th edition, New York, Garland publishing
- ↑ C.H.Heldin & M Purton, 1996, Signal transduction, Chapman & Hall