Phosphatidyl inositols
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
Individual evidence
- ↑ 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 .