Phosphatidylinositol 3,4,5-trisphosphate (PIP3) (PIP3)

Phosphatidylinositol 3,4,5-trisphosphate (PIP3) is a critical phospholipid second messenger located within the inner leaflet of the plasma membrane (PubChem CID 24850). It is generated from phosphatidylinositol 4,5-bisphosphate (PIP2) by the action of Class I phosphoinositide 3-kinases (PI3Ks) in response to extracellular stimuli such as growth factors, cytokines, and insulin (NCBI, PMC6133347). PIP3 functions as a docking platform for proteins containing pleckstrin homology (PH) domains, most notably the serine/threonine kinase AKT and its activator PDK1, thereby initiating signaling cascades that regulate cell survival, growth, and metabolism (Nature Reviews Molecular Cell Biology, 2008). The levels of PIP3 are tightly regulated by the tumor suppressor phosphatase PTEN, which converts PIP3 back into PIP2 (PubMed, 10364221). Dysregulation of this balance, typically through PIK3CA mutations or PTEN loss, leads to constitutive signaling and is a primary driver in various cancers and metabolic diseases like Type 2 diabetes (StatPearls, NBK557544). While PIP3 itself is not a protein target, it is the central node of the PI3K/AKT/mTOR pathway, which is targeted by several FDA-approved inhibitors such as alpelisib and idelalisib to treat malignancies (FDA, 2019).

Other names

PtdIns(3,4,5)P3Phosphatidylinositol-3,4,5-trisphosphate1-phosphatidyl-1D-myo-inositol 3,4,5-trisphosphatePIP3

Inhibition of Class I Phosphoinositide 3-kinases (PI3K) to prevent the conversion of PIP2 to PIP3, or activation/restoration of PTEN phosphatase activity to degrade PIP3.