But let's discuss integral proteins, and let's take a look at three specific examples that we have studied extensively. So let's discuss bacteria, porin and prostaglandin h two, synthase one. And let's begin with bacteria. Now, bacteria, doptopsin is a transmembrane into a protein, and that means it spans the entire membrane. And these transmembrane proteins are found in special types of archaeal bacterial cells. Now, the function of this protein is to basically use the energy that is stored in light to basically create a proton gradient.