Phosphoinositide 3-kinase family (PI3K)

The phosphoinositide 3-kinase (PI3K) family comprises intracellular enzymes that phosphorylate the 3-position of the inositol ring in phosphoinositides, primarily converting PI(4,5)P2 to PI(3,4,5)P3 to activate downstream signaling via AKT and mTOR, regulating critical processes like cell growth, proliferation, survival, motility, and metabolism. Divided into classes I-IV based on structure, regulation, and substrate specificity, class I PI3Ks (e.g., p110α/PIK3CA) are heterodimers activated by receptor tyrosine kinases and GPCRs, strongly implicated in oncogenesis due to frequent mutations in cancers like breast and bladder. Class II and III isoforms contribute to membrane trafficking, endocytosis, and autophagy. Dysregulation drives tumorigenesis, insulin resistance, and aging-related pathologies, positioning PI3K as a key therapeutic target. isoform-selective inhibitors block pathologic signaling but face challenges like on-target toxicities including hyperglycemia from metabolic disruption and immunosuppression.

Other names

Phosphatidylinositol 3-kinasePI 3-kinasePI 3-KsPhosphoinositide-3-kinase

ATP-competitive inhibition of lipid kinase activity, preventing PIP3 production and downstream AKT/mTOR signaling