Fig. 5.

Proposed model of PADI evolution. Domain architecture is denoted in the figure legend. Horizontal transfer of the three-domain sequence from cyanobacteria to metazoa denoted by a black arrow, likely horizontal transfer of the two-domain sequence from actinobacteria to fungi denoted by a dark gray arrow and transfer of the mitochondrion to the LECA denoted by a light gray arrow. Proposed origin for the PADI sequence is within bacterial evolution and emergence of the three-domain PADI is within the SPX/NM cyanobacterial clade. Gene losses observed in various metazoan lineages after the HGT are indicated with a narrow dashed line.