Figure 3

Most parsimonious reconstruction of the patterns of emergence and loss of HECT E3s in animals. Arrows indicate the emergence of new genes (indicated in the boxes) and rectangles, a gene loss. Question marks indicate cases in which it is unclear that a gene is present or not, due to partial data. The names NEDD4a-d refer to the four ancestral genes of the NEDD4 subfamily that still exist in many animals (Table 1) and that emerged before the metazoa/choanoflagellata split. In humans, the genes NEDD4 and NEDD4L derive from a duplication of NEDD4a, WWP1, WWP2 and ITCH derive from NEDD4b, Smurf1 and Smurf2 from NEDD4c and NEDL1 and NEDL2 from NEDD4d. The partial data available for lophotrochozoans (in brackets) allows concluding that all genes are present in at least one species of this group of organisms, and therefore they were all present in their common ancestor. However, losses in particular lineages may have occurred.