PIP2

PIP2 or phosphatidylinositol bisphosphate is a general term that refers to the products obtained by cleavage of PIP3.

PIP2 is a substrate for cleavage with phospholipase C (PLC), a membrane-bound enzyme activated through protein receptors like α1 adrenergic receptors. Products of this reaction are inositol triphosphate (IP₃) and diacylglycerol (DAG).

In this cascade, DAG remains on the cell membane and activates the signal cascade by activating protein kinase C (PKC). PKC in turn activates other cytosolic proteins by phosphorylating them. The effect of PKC could be reversed by phosphatases.

IP₃ enters the cytoplasm and activates IP₃ receptors on the smooth endoplasmic reticulum (ER), which opens calcium channels on the smooth ER, allowing mobilization of calcium ions through specific Ca²⁺ channels into the cytosol. Calcium participates in the cascade by activating other proteins.

See also

* Phosphatidylinositol (3,4)-bisphosphate
* Phosphatidylinositol (4,5)-bisphosphate
* Phosphatidylinositol (3,5)-bisphosphate