Interaction of Ras with phosphoinositide 3-kinase γ

Abstract

Phosphoinositide 3-kinase γ (P13Kγ) can be activated in vitro by both α and βγ subunits of heterotrimeric G-proteins and does not interact with p85, the regulatory subunit of P13Kα. Here we demonstrate the binding of Ras to P13Kγ in vitro. An N-terminal region of P13Kγ was identified as a binding site for Ras. After co-expression with P13Kγ in COS-7 cells, Ras induced only a modest increase in P13K activity compared with the stimulation of P13Kα by Ras in the same cells.