So this is a signal transduction pathway that essentially allows us to carry out these two processes to turn on glycogen breakout and turn off glycogen synthesis. So let's imagine where in our liver cell so we have glucagon and to a very small extent epinephrine are the primary messengers that bind to these receptor molecules on liver cells. And once the glucagon binds onto the glucogon receptor it basically stimulates the GDP to leave and a GTP to enter this green g protein. And that stimulates the g protein to dissociate and go on and bind to adenylate cyclase, another membrane bound protein. Once bound, it stimulates adenylate cyclase to begin creating secondary messenger molecules. So it transforms ATP into cyclic amp.