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. Now it's the cyclic Amp that acts as a secondary messenger. It goes on and binds onto regulatory sites of protein kinase A and that activates it by allowing the catalytic sites or the catalytic units to actually dissociate from that regulatory site from that regulatory subunits. And so that activates protein kinase A.