PI 3-Kinases (Phosphoinositide 3-Kinases)
Class IA phosphoinositide 3-kinases (PI 3-kinases) are a family of p85/p110 heterodimeric lipid kinases that function as signal transducers downstream of growth factor receptors, mainly receptor tyrosine kinases. Mammals express three class IA catalytic subunits: p110 alpha, p110 beta, and p110 delta. Reports suggest that the p110 beta subunit may have special importance in promoting cell proliferation, while the p110 delta subunit is expressed predominantly in leukocytes, indicating that it may play a role in immune signaling. The class IB p110 delta subunit is activated by G protein-coupled receptors.