Guanine nucleotide-binding proteins (G proteins) are involved as a modulator or transducer in various transmembrane signaling systems. The beta and gamma chains are required for the GTPase activity, for replacement of GDP by GTP, and for G protein-effector interaction. G proteins are composed of 3 units, alpha, beta and gamma. Interacts with RASD2 (By similarity). Expressed at a high level in the heart and at a much lower level in the brain. Belongs to the WD repeat G protein beta family.