And this colored loop is known as the P loop structure. And we'll see why we call it the P loop in just a moment. Then we have the first alpha helix and then we continue. We have the second beta sheets, then we continue, we have the second alpha helix, we continue, we have the third beta sheet and so forth and we continue all the way until we get to the end. Now what's so special about this colored loop? Well, this loop is known as the P loop.