And instead of drawing out this complex structure, we're going to represent this complex structure with this green structure here. So this is the seven TM domain, and this pocket is the pocket shown here to which the epinephrine actually binds to. Now let's take a look at the structure of the beta adrenergic receptor. Now, before the epinephrine actually binds to this section here, this is what it looks like. So notice on the intracellular side, we have a heterotrimer structure. And what that means is we have three different domains that create a trimer attached onto this seven TM domain.