PI3Kkomplex

The PI3Kkomplex refers to a cellular signaling pathway initiated by phosphoinositide 3-kinases (PI3Ks). These enzymes are crucial for a wide array of cellular processes, including cell growth, proliferation, survival, and metabolism. PI3Ks are activated by growth factors, cytokines, and other extracellular signals that bind to receptor tyrosine kinases or G protein-coupled receptors on the cell surface.

Upon activation, PI3Ks catalyze the phosphorylation of phosphatidylinositol 4,5-bisphosphate (PIP2) at the 3-hydroxyl position of the inositol ring, generating phosphatidylinositol 3,4,5-trisphosphate (PIP3). PIP3 acts as a second messenger, recruiting downstream effector proteins that contain pleckstrin homology (PH) domains to the plasma membrane. A key downstream effector is the serine/threonine kinase Akt (also known as Protein Kinase B or PKB).

The PI3K/Akt pathway plays a significant role in cell survival by inhibiting pro-apoptotic proteins and promoting anti-apoptotic factors. It also regulates cell growth by activating pathways that stimulate protein synthesis and inhibit protein degradation. Furthermore, this pathway is deeply involved in glucose metabolism, promoting glucose uptake and glycogen synthesis. Dysregulation of the PI3Kkomplex is implicated in various diseases, particularly cancer, where it can contribute to uncontrolled cell proliferation and survival. Consequently, the PI3K pathway is a major target for therapeutic interventions in oncology.