Lipid Kinase

Lipid kinases phosphorylate the inositol head group of phosphoinositides rather than protein substrates, generating signaling phospholipids that recruit cytosolic effectors to membranes. The family includes the phosphoinositide 3-kinases (PI3K classes I, II and III), the PI4-kinases, phosphatidylinositol phosphate kinases and the PIKfyve complex. Their products — such as PIP3 and PI(3,5)P2 — drive AKT activation, endosomal sorting, autophagy and vesicular trafficking. Class I PI3K sits downstream of receptor tyrosine kinases and is one of the most frequently activated pathways in human cancer, and PI3K inhibitors are approved oncology drugs. These enzymes are also central to insulin signaling and to immune cell function.