Phosphatidyl inositols

Structural formula of PIP ₂ , R stands for the fatty acid residues capryl , oleyl , palmityl , arachidonyl or stearyl

Phosphatidylinositols (also phosphoinositides ) are phosphatidic acids of inositol and thus belong to the phosphoglycerides . They occur as polar lipids in the cell membrane and serve, among other things, as a precursor for secondary messenger substances .

properties

The phosphoinositides include, for. B. Phosphatidylinositol-4,5-bisphosphate , phosphatidylinositol-3,4-bisphosphate and phosphatidylinositol-1,4,5-trisphosphate (PIP ₃ ). The inositol is phosphorylated several times . By activating certain receptors located in the cell membrane, the enzyme phospholipase C is activated . Phospholipase C splits PIP ₂ by hydrolysis into diacylglycerols (DAG) and inositol-1,4,5-trisphosphate (IP ₃ ), while phospholipase A produces lysophosphatidylinositol . All three products of this cleavage can contribute as secondary messenger substances to the transmission of the signal in the cell. Other phosphoinositols are formed analogously .

Phosphoinositide-3-kinases (PI3K), on the other hand, convert PIP ₂ into phosphatidylinositol-3,4,5-triphosphate (PIP ₃ ). The reverse reaction from PIP ₃ to PIP ₂ is carried out by the phosphatase PTEN .

Web links

Wikibooks: Inositol Phosphate Metabolism  - Learning and Teaching Materials

Individual evidence

1. ↑ York Posor, Marielle Eichhorn-Gruenig: Spatiotemporal control of endocytosis by phosphatidylinositol-3,4-bisphosphate. In: Nature. 499, 2013, pp. 233-237, doi : 10.1038 / nature12360 .