The α-isoform of class II phosphoinositide 3-kinase is more effectively activated by insulin receptors than IGF receptors, and activation requires receptor NPEY motifs

AbstractLittle is known about the physiological role and mechanism of activation of class II phosphoinositide 3-kinases (PI3Ks), although it has been shown that the PI3K-C2α isoform is activated by insulin. Using chimaeric receptor constructs which can be activated independently of endogenous receptors in transfected cells, we found that PI3K-C2α activity was stimulated to a greater extent by insulin receptors than IGF receptors in 3T3-L1 adipocytes. Activation of PI3K-C2α required an intact NPEY motif in the receptor juxtamembrane domain. We conclude that PI3K-C2α is a candidate for participation in insulin-specific intracellular signalling