Cluster tree for ubiquitin. The attribute clusters discovered from the aligned sequence data for the ubiquitin family are shown above and organized vertically according to their order (the number of interdependent sites they contain). The organized clusters form primary branches, numbered 1 to 14 across the top of the figure. In each branch, the attribute cluster with the highest internal interdependency (highest SR(mode) value) was chosen as the representative cluster for that branch and is labeled according to its branch number. Two secondary clusters, discussed in the text, are labeled 12 s and 13 s. From this cluster tree, new insights can be gained into details of folding and structure.