Considering the relative binding affinities and adenylate cyclase activity as a function of hormone concentration, what can you conclude about the mechanism of action of the hormone–receptor complexes?

The binding affinity almost perfectly matches the ability to stimulate adenylate cyclase, suggesting that the hormone-receptor complex leads to the stimulation of adenylate cyclase.

Explanation:

Bound receptor interacts with and, through a set of G proteins, turns on adenylate cyclase, which is also an integral membrane protein. Activated adenylate cyclase begins to convert ATP to cyclic AMP, resulting in an elevated intracellular concentration of cAMP.

Adenylyl cyclase (ADCY, EC number 4.6. 1.1), also known as adenylate cyclase, is an enzyme which catalyzes the cyclization of adenosine triphosphate (ATP) into cyclic adenosine monophosphate (cAMP) which requires the cleavage of pyrophosphate (PPi).