Diacylglycerol kinase γ interacts with and activates β2-chimaerin, a Rac-specific GAP, in response to epidermal growth factor

Diacylglycerol kinase (DGK)γ was shown to act as an upstream suppressor of Rac1. Here we report that, in COS7 cells stimulated with epidermal growth factor (EGF), DGKγ specifically interacts and co-localizes at the plasma membrane with β2-chimaerin, a GTPase-activating protein (GAP) for Rac. Moreover, DGKγ enhanced EGF-dependent translocation of β2-chimaerin to the plasma membrane. Interestingly, DGKγ markedly augmented EGF-dependent GAP activity of β2-chimaerin through its catalytic action. These results indicate that DGKγ is a novel regulator of β2-chimaerin, and thus suggest that β2-chimaerin is an effector molecule, linking DGKγ functionally with Rac1.