 So in fact, as structure determination techniques have become better and better, we see more and more structures that are some sort of complexes. Not quite lipid wrapped, but not that far away from it. This is an example of a deep protein coupled receptor that you will hear more about later on in the class, but briefly it's a protein very similar to that first bacterial rhodopsin structure I talked about. Also seven transmembrane helices here. But here do you see how it's oriented as a dimer? And we even have a bunch of cholesterol bound to it in the middle. And here we're then showing it in a surrounding of lipids. So this is almost a micro lipid raft per se, although it's just one small dimer of a protein. But again, something we see in the experiment. So there are more and more examples where we can see not just the protein, but even lipids in experimental data. And that has led to a bunch of interesting things. What if we could determine general lipid interactions in experiments? Well, not so fast. That's not going to work. It works if the lipids are so rigidly bound that they're really part of the structure, so that they're part of the structure the same way in billions of copies of the protein in the crystal. But the lipid that just interacts with the protein in different ways in each copy, that would average out. You would never see it. And I would also like something that's not in one of these idealized membranes, but in a live cell ideally. That's not easy, but there are some new very powerful techniques based on mass spectrometry. This is not a methods class, but mass spectrometry briefly works by cutting proteins into small segments, and then we accelerate them in an electric field. And based on where they land on a detector, that gives them a relation between the charge and the mass of the fragments. And if I then compare that to the amino acid sequences I expected to find, I can frequently in this database identify what amino acid fragments I had. If you translate that to membrane proteins and lipids, the trick is that if I am able to break the protein in parts, but still keep the lipids attached to it, native mass spectrometry, I can occasionally use this to detect at least which one of a few lipids candidates appears to be the one that's bound. Carol Robinson, the UK, is the master behind behind these techniques, but we also have an exceptionally skilled junior group Michael Landry at the Carolinus Gay Institute and SyLive Lab, who is a pioneer in this field together with Carol. And again, when this works, I can see what lipids are bound. I can see how tightly bound they are, how rapidly they appear to exchange with the environment. And in a few cases, if we combine this with measuring what lipids I have present in the cell in the first place, I might be able to use a lipidomics approach and from scratch identify are there any lipids specifically binding to this particular membrane protein and which ones in that case. It's a potentially very promising technique that I think is going to take off in ways we can't even imagine the next few years.