Phosphoinositide 3-kinase Regulatory Subunit Alpha (p85α)

Phosphoinositide 3-kinase regulatory subunit alpha (p85α) is a key regulatory component of class IA phosphoinositide 3-kinases (PI3Ks), involved in cell growth, proliferation, survival, metabolism, and immune function. It forms a complex with catalytic subunits like p110α, modulating their activity and stability. Beyond its role in regulating PI3K enzymatic activity, free or homodimerized forms of p85α have additional functions, including stabilizing PTEN and modulating insulin signaling. Mutations can disrupt inhibitory control over PI3K activity, leading to aberrant activation of downstream signaling pathways implicated in oncogenesis. It is essential for proper regulation and localization of class IA PI3Ks and acts both as an inhibitor and stabilizer for catalytically active partners. It also has independent roles outside canonical heterodimers—including tumor suppression via PTEN stabilization.

Other names

PI3K p85αPik3r1

Allosteric regulation of PI3K catalytic subunits, Stabilization of PTEN