And this means that enzymes, substrate molecules that contain serene or threeamine surrounded by this specific sequence will be recognized by the protein kinase A and the protein kinase A will bind onto this section and will phosphorylate this target side. And by phosphorylate it can basically change the activity and the functionality of that target substrate molecule. Now, earlier we said that it's a cyclic ANP molecule that actually binds and activates protein kinase A. Now, the first question is what exactly is the quarterly structure of protein kinase A when it is not bound to the cyclic Amp? What is the inactive quarter structure of protein kinase A? So this is basically shown on the board.