 So, since it's so important to determine structures of membrane proteins, I'm going to share with you how we determine that because that is based on understanding lipid protein interactions itself. In general, a membrane protein is going to be hydrophobic on the sides, and that means that I can't just solvate it in water. In the real membrane, that works because we have lipids. We have an entire lipid membrane around it, right? But if I were to just tear this out of the membrane, I would break up the protein, so that's not going to work. And yet, to be at least be able to take an x-ray crystal of this, I need to somehow crystallize it. I can't crystallize a membrane because the membrane is saliently oiled. But there are other molecules. In particular, micelles, detergents, detergent micelles, it's essentially soap. If I put many detergents like that in water, their chains will face each other. But since there's typically just one chain, they're going to form small spherical micelles instead of bilayers. If I now extract the membrane protein here, but then I add a lot of micelles, what I end up with is roughly the situation. So I have the membrane protein with its hydrophobic parts. And on all these sides, I will now have micelles bound. And I'm going to have enough micelles bound now that all of it will effectively be water soluble. Here, I already had water soluble parts. But the micelles per se are now also water soluble. So this suddenly becomes a water soluble complex. If you're doing cryo-EM, we can throw that directly under a microscope. But you can also crystallize it. This is what Hartmut Michel did with the bacteria rhodopsin. And if I draw this in a schematic way, if you now have lots of copies of that, the parts that are water soluble here, they're going to be just fine. They will pack. And the parts that are fat soluble, well, in this region, we would have those micelles. I will leave it as an exercise for you to draw the remaining 100 billion molecules here. This can form a nice stable periodic crystal. And that's how Hartmut Michel got the structure of bacteria rhodopsin and eventually a noble prize for their work in 1988, if I recall correctly. That one, we can use directly in cryo-EM. And over the years, we've developed this taste of trying to get something ideally even closer to the membrane. This is not horribly bad, but it's certainly not the membrane environment, right? And there could be important differences between these two. So if I really wanted a membrane environment, I would like something like this. And I'm going to show you a way we can do that.