Now, porin is basically a transmembrane protein that exists in certain bacterial cells, for instance, E. Coli cells, and it exists on the outer membrane of those on the outer layer of the membrane of those bacterial cells. Remember, some cells have actually two membranes and this porn exists on the outer membrane. Now, porin is actually a channel. So it's a pore, it's a hole inside the membrane. And what this consists of are these beta pleated sheets that run in an antiparallel direction and they basically curl and create this channel. Now, they create the channel because this, because the function of this is to basically move polar molecules across the cell membrane.