So when the epinephrine binds to this section, it basically causes the alpha subunit to decrease its affinity for the beta subunit and the alpha subunit. And what happens is our GDP, which is the guanosine diphosphate, is converted into the guanosine triphosphate or GTP and that decreases the affinity of the alpha subunit, our G protein. And this goes on and bind onto this adenylate cyclase. And once it binds onto our adenylene cyclase it causes the conversion of ATP adenosine triphosphate to cyclic adenosine monophosphate or CA MP. And then this is our secondary messenger. So our epinephrine is the primary or first messenger involved in the signal transduction process and this is the second molecule involved.