What is the functionality of protein kinase a? When does our body actually use protein kinase A? Well, in dangerous or exciting or stressful situations, recall that it's the sympathetic division of our nervous system that kicks in and initiates the flight or fight response. And what happens is the sympathetic nervous system basically stimulates the adrenaline dula to release a hormone we call epinephrine. And as epinephrine travels through our cardiovascular system, it basically stimulates our cells to transform ATP molecules into another molecule known as cyclic adenosine monophosphate or simply camp. Now, what canp does is it's an allosteric regulator of protein kinase a and as we'll see in just a moment, it binds onto the inactive version of protein kinase A and it activates protein kinase A and protein kinase A.