Adenylate cyclase activation. (A) Adenylate cyclase is a membrane protein with two large intracellular domains that contain the catalytic apparatus. (B) The structure of a complex between Gα in its GTP form bound to a catalytic fragment from adenylate cyclase. Notice that the surface of Gα that had been bound to the βγ dimer now binds adenylate cyclase.
[Drawn from 1AZS.pdb.]