These receptors have an extracellular component found outside the cell and an intracellular component found inside the cell. And that ligand, that primary messenger shoulder red actually binds onto the outside portion of that transmembrane protein, the receptors. So this is the membrane, the outside the cell, the inside the cell. And notice that this ligand, the primary Messer, binds onto this region on the outside. And once it binds, it creates a conformational change that in some cases basically causes a portion of that protein on the intracellular side to basically detach. And that can lead to other processes as we'll see in lectures to come.