So, we begin in the alpha cells of the pancreas. The alpha cells of the pancreas basically produce this peptide hormone we call glucagon. And once glucagon makes its way into the bloodstream, it then travels onto the membrane of liver cells. On the membrane of liver cells is a receptor, a seven transmembrane receptor, seven TM receptor known as the glucagon receptor. And glucagon binds onto this side of this glucagon receptor, shown in orange. And once the binding takes place, that initiates a process on the other side of this seven TM receptor protein.