So, for instance, in our discussion on the epinephrine signaling pathway we said that that pathway actually uses G proteins and those receptors are known as G coupled protein receptors. But in this particular case, for the case of insulin we don't actually use any G proteins. Instead, we actually have protein kinases found within the structure of this receptor. Now, what happens when the insulin actually binds? So insulin is the primary messenger of this particular pathway and the insulin shown in orange binds into this cavity that is created by these two alpha units. And once the insulin actually moves in these two structures the alpha units actually close in.