Now, we have different types of glycoproteins. The two glycoproteins we're going to focus on in this lecture is a glycoprotein called GP 120 and glycoprotein called GP 41. So GP 120 is positioned on top of GP 41. Now, GP 120 is actually used to bind onto receptors on the target cell's membrane and GP 41 is used to stimulate the process of fusion of the membrane of the virus and the membrane of the target cell. Now, inside this membrane we have the protein capsule shown in brown and inside that protein capsite we have the contents of that virus. We have the genetic information, the RNA shown in red and we have two very important types of protein enzymes.