 The quaternary structure tab shows the templates represented in a tree, which clusters the templates at different levels. First, we see that the tree is grouped into monomers and homomers, then according to the stoichiometry, in our case dimers and tetramers. This little figure here represents the topology of the interaction between the protein chains. If we look at the tetramer, it looks like four beads on a string. If in another template the first and the last protein chain would interact, it would be shown in a separate cluster. Perhaps it would look like a closed necklace, for example. The last level clusters according to interface similarity, meaning how the protein chains interact with each other. Let's select one to see afterwards what this means exactly. The green lines show templates which likely lead to models with the correct quaternary structure. If you place your mouse over it, you see the quaternary structure quality estimate. The cutoff is at 0.7. You see here the two templates that we selected. From this quaternary structure score, we might also want to build a model of the top two. You can see in the window that the tertiary structure is very similar between the templates. The last plot we will explore on this page is the protein-protein interaction fingerprint. Here on the x-axis, we see the sequence identity and on the y-axis, interface conservation. These plots inform about the conservation of template interfaces. A value of interface conservation below zero indicates that interface residues are less prone to mutate compared to surface residues. The estimate is calculated from a multiple sequence alignment using different identity cutoffs. We can see here that the top dimer cluster seems to have the most conserved interface and thus most likely represents the correct oligomeric state of our protein.