So let's actually take a look and see what happens during our secondary messenger system signal transduction. So basically some type of cell, some type of gland in our body releases this hormone known as epinephrine. Eventually this epinephrine reaches the receptor of that specific cell and that receptor is found on the membrane. So this is the protein complex. The green is our beta adrenergic receptor. It contains the receptor that basically binds our epinephrine.