 Hello, my name is Shelley Defort and I'm going to introduce a paper that myself and Dr. Vladimir Yuversky recently published in Protein Science that is titled Resolving the Ambiguity, Making Sense of Intrinsic Disorder when PDB Structures Disagree. There is a long-standing assumption that the unique three-dimensional structure of a protein determines its function. However, there is a whole class of proteins that break this assumption. These are called intrinsically disordered proteins and they come in many flavors. They can be entirely disordered, partially disordered, or conditionally disordered. They can have long stretches of disorder or short stretches. And most importantly, there is a huge body of research that shows that these intrinsically disordered proteins and protein regions are often functionally important. It can be challenging to identify these proteins experimentally and so a lot of the information we have about the sequence characteristics that lead to protein intrinsic disorder has actually been obtained through the analysis of X-ray crystal structure data, which is weird because normally when you think of X-ray crystal structures, you think of, well, structure and not disorder. But let's look a little bit more closely at this structure here, which is activated G-alpha-q bound to phospholipase C-beta-3. If you take this structure into molecular visualization software to view the model, you'll get a dash line, which represents a gap in the three-dimensional model. Now a lot of people are interested in how we can fill in the missing information, but there are also a lot of people who are interested in why there wasn't enough electron density to build this part of the model in the first place, because sometimes this indicates an intrinsically disordered region of the protein. However, when a protein has more than one crystal structure available, sometimes a region will be missing in one structure, but resolved in another, or more commonly, the length of the missing region will not be the same between the structures. These regions are called ambiguous regions. So the question we're asking is, what does this ambiguity mean? Is the missing region an experimental artifact? Is it caused by static disorder, which can be caused by the movement of a large structured region by a small hinge or by an ensemble of structures? Or does an ambiguous region still indicate protein intrinsic disorder, and if so, how do we make sense of the variability between crystal structures? So we developed a method where we could examine the ambiguous regions by the pattern of missing residues between the structures. We found that it was really common to see one crystal structure that had a longest missing region that encompassed all others. We analyzed a lot of things like secondary structure variability, amino acid composition, and the location of the missing region, as well as predicted disorder in these regions. Our results led us to conclude that ambiguous regions are not, in most cases, experimental artifacts or domain wobble, which is where you have a structured region moving as a unit. Instead, our results suggest that the ambiguity is arising due to partially or conditionally disordered regions that may display variable amounts of residual secondary structure, depending on the context the protein is placed in. We hope these results are useful to both structural and unstructural biologists who work with expert crystal structure data. We would love to hear from you if you have questions about our research, and you can view and download the custom scripts used to do this analysis on GitHub. Thank you so much for watching.