And these two regions of the beta soviets basically contain a very important section that gives this receptor its activity. And this section contains the tyrosine protein kinase domains. Now, a tyrosine protein kinase is basically an enzyme, a protein that phosphorylates tyrosine amino acids on target proteins and enzymes. And we'll see what those are used for in just a moment. So this is what the insulin receptor actually looks like. Now, notice there's an important difference between this insulin receptor and the receptors that we spoke of previously.