Inositol phosphates

Inositol

Phosphate group, R = inositol

Inositol phosphates (synonym phosphoinositols ) are a group of phosphorylated inositols . As secondary messenger substances, they are involved in signal transduction in cells .

properties

The phosphoinositols include, for. B. inositol phosphate, inositol-4,5-bisphosphate , inositol-3,4-bisphosphate , inositol-1,4,5-trisphosphate (IP ₃ ), inositol-tetrakisphosphate , inositol-pentakisphosphate (IP ₅ ) and inositol-hexaphosphate ( IP ₆ , synonymous with phytic acid ). The inositol is one or more times esterified with phosphate groups . Phosphoinositols are released from phosphatidylinositols in the course of signal transduction of the Akt signaling path on the inside of the cell membrane by enzymatic hydrolysis . Among other things, they are involved in the restructuring of chromatin in the course of transcription and in endocytosis . They also inhibit the activity of Ca ²⁺ - ion channels of the TRP family.

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 A2 produces lysophosphatidylinositol . All three products of this cleavage can contribute as secondary messenger substances to the transmission of the signal in the cell.

Phosphoinositide-3-kinases (PI3K) 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 .

Individual evidence

↑ ^a ^b ^c X. Shen, H. Xiao, R. Ranallo, WH Wu, C. Wu: Modulation of ATP-dependent chromatin-remodeling complexes by inositol polyphosphates. In: Science. Volume 299, Number 5603, January 2003, pp. 112-114, doi : 10.1126 / science.1078068 , PMID 12434013 .
↑ DJ Steger, ES Haswell, AL Miller, SR Wente, EK O'Shea: Regulation of chromatin remodeling by inositol polyphosphates. In: Science. Volume 299, number 5603, January 2003, pp. 114-116, doi : 10.1126 / science.1078062 , PMID 12434012 , PMC 1458531 (free full text).
↑ ^a ^b 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 .
^ AP Albert: Gating mechanisms of canonical transient receptor potential channel proteins: role of phosphoinositols and diacylglycerol. In: Advances in Experimental Medicine and Biology . Volume 704, 2011, pp. 391-411, doi : 10.1007 / 978-94-007-0265-3_22 , PMID 21290308 .

[Shen-1] X. Shen, H. Xiao, R. Ranallo, WH Wu, C. Wu: Modulation of ATP-dependent chromatin-remodeling complexes by inositol polyphosphates. In: Science. Volume 299, Number 5603, January 2003, pp. 112-114, doi : 10.1126 / science.1078068 , PMID 12434013 .

[2] DJ Steger, ES Haswell, AL Miller, SR Wente, EK O'Shea: Regulation of chromatin remodeling by inositol polyphosphates. In: Science. Volume 299, number 5603, January 2003, pp. 114-116, doi : 10.1126 / science.1078062 , PMID 12434012 , PMC 1458531 (free full text).

[Posor-3] 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 .

[4] AP Albert: Gating mechanisms of canonical transient receptor potential channel proteins: role of phosphoinositols and diacylglycerol. In: Advances in Experimental Medicine and Biology . Volume 704, 2011, pp. 391-411, doi : 10.1007 / 978-94-007-0265-3_22 , PMID 21290308 .