Brain I3 Binding Protein regulates K-Ras4B membrane localization and signaling

Membrane localization of Ras proteins is necessary for their biological functions and oncogenic activity. We report here on the identification of Brain I3 Binding Protein (BRI3BP) as a novel binding partner for Ras. We show that K-Ras4B plasma membrane localization and biological function are reduced in the absence of BRI3BP. BRI3BP interacts with K-Ras4B and K-Ras4A and our data suggest that BRI3BP operates within the recycling endosomal compartment to regulate K-Ras localization to the plasma membrane. This study uncovers a new regulatory protein for Ras membrane localization.