Network motifs and evolutionary motif modes. There are two interconnected patterns for 3-motifs and six for 4-motifs. Evolutionary motif modes of a 3-motif and a 4-motif of specific topology are shown, different node colors indicating different protein age classes. For example, for each 4-motif of specific topology, in total there are five possible evolutionary motif modes which are marked as #4, #3-1, #2-2, #2-1-1 and #1-1-1-1. The label for an evolutionary motif mode indicates the number of nodes of different age classes within the motif mode. For example, #4 indicates that all the four proteins within the motif mode are of the same age class, and #2-2 indicates that two of the four proteins within the motif mode are of one age class, while the other two are of another age class.
Liu et al. BMC Evolutionary Biology 2011 11:133 doi:10.1186/1471-2148-11-133