So we're gonna start out with the cyclic AMP second messenger system. And to this receptor, some messenger will bind to the receptor and that will start the second messenger system. So it's a way that a messenger on the outside can send the signal to the inside of the cell without having to actually cross the plasma membrane.
So at the other end of this receptor, you have a G protein.It's the alpha subunit.
• When this messenger binds to the receptor, this alpha subunit dissociates from this G protein and comes across and binds to a protein that's also on the plasma membrane called adenylate cyclase.
• Now when this alpha subunit binds to adenylate cyclase, so this is a simplified version for what you need to know and how this is gonna help you answer questions, that alpha subunit binds to adenylate cyclase and this causes ATP to be converted into cyclic AMP.
• So ATP gets converted into cyclic AMP, which then, the cyclic AMP goes and activates protein kinases A.
• And then the protein kinases A, all that does is it makes it possible for some protein that is unphosphorylated to become a protein that is phosphorylated. So what do you need to know?