Snapshot of activated G proteins at the membrane:: The Gαq-GRK2-Gβγ complex

G protein-coupled receptor kinase 2 (GRK2) plays a key role in the desensitization of G protein-coupled receptor signaling by phosphorylating activated heptahelical receptors and by sequestering heterotrimeric G proteins. We report the atomic structure of GRK2 in complex with G alpha(q) and G beta gamma, in which the activated G alpha subunit of G(q) is fully dissociated from G beta gamma and dramatically reoriented from its position in the inactive G alpha beta gamma heterotrimer. G alpha(q) forms an effector-like interaction with the GRK2 regulator of G protein signaling (RGS) homology domain that is distinct from and does not overlap with that used to bind RGS proteins such as RGS4.