Now, the final example we're going to look at is the prostaglantin h, two synthase, one. And this is actually an example of an integral protein that is not a transmembrane protein. And what that means is it doesn't actually span the entire width of the membrane, but it does contain a good portion that actually does interact with that core. And that's why we call it an integral protein. So if we basically change our PH or add a salt solution this will not dissociate because a good portion of it actually is permanently bound to that cell membrane. Now, where do we find these molecules?