Guanine nucleotide-binding proteins (G proteins) are involved as modulators or transducers 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 the gamma subunits RGG1 and RGG2. Belongs to the WD repeat G protein beta family.