Class I and Class II discriminating class-specific elements for 50 species. Discriminating class-specific elements were generated as illustrated in Figures 1 and 2 and were listed for both the Class I (upper panel) and the Class II (lower panel) set. Each panel is separated into three subsections according to the three domains of life, Eukarya, Archaea and Bacteria. In order to highlight positions where the majority of species in a domain contain discriminating class-specific elements, these elements are highlighted with colored background using the following scheme: (i) magenta for Eukarya, (ii) yellow for Archaea, (iii) cyan for Bacteria. Note that for positions where more than one type of discriminating elements exists, we use the corresponding IUPAC code to describe the level of degeneracy (see in the legend of Figure 1.). For easier interpretation of the data, we also show the consensus of the discriminating class-specific elements for the kingdom-level using kingdom-specific color, and the same color-coding is used in Figure 5, which shows the overall distribution and sharing of these elements among the three kingdoms of life.