P27986, Q92569 

PI3 kinase also known as phosphoinositide-3-kinase is a heterodimer composed of a regulatory subunit (p85) and a catalytic sub unit (p110), and phosphorylates phosphoinositides at the 3′ OH position of their inositol rings. The p85 subunits, including p85α, p85β, and p55γ, serve as regulatory adapters that anchor the catalytic subunit to activated receptor tyrosine kinases at the plasma membrane. Such localization is essential for signal transduction, as positioning near lipid substrates initiates pathways like AKT/mTOR that regulate cell growth, survival, and metabolism. PI 3-kinase p85α (also known as GRB1 or phosphatidylinositol 3-kinase regulatory 1) plays a key role in insulin signaling, and dysregulation has been linked to conditions such as insulin resistance and cancer. Post-translational modifications, including tyrosine phosphorylation and ubiquitination, modulate p85 subunit activity and stability, further refining signaling pathway control.