The water molecule is taken and basically is used to hydrolyze the GTP into GDP. And so we release a single phosphate molecule. And so once this is formed, the affinity of the G protein decreases for that adenocyclase, it basically dissociates and goes on and finds that dimer to form this trimmer protein. Now, let's move on to diagram B. So this is the second site, the second point in the pathway where the cell can actually deactivate, shut down that pathway, and this is when that epinephrine is bound onto the site on the beta adrenergic receptors. So what is the function of this structure?