Figure 4.

The evolutionary conservation of 41 ATG genes across 164 species. ATG39, ATG40 and ATG41 were exclusively found in the yeast S. cerevisiae, whereas ATG25 and ATG30, ATG35 and ATG37 are only encoded in the K. pastoris. We classified ATG11 and ATG17 into a single group due to the sequence similarity in more complex eukaryotes and the functional similarity in autophagy. Based on the sequence and functional similarity, we also classified ATG3 and ATG10, ATG18 and ATG21, as well as ATG20 and SNX4/ATG24 into 3 groups, respectively. Clearly, there were 18 highly conserved ATG genes including ATG1 to ATG10, ATG11 and ATG17, ATG13, ATG16, ATG18 and ATG21, ATG20 and SNX4/ATG24. Their orthologs were detected in more than 85% (140) of 164 eukaryotes, and most of these ATG genes are involved in autophagosome formation.