General summary of the evolutionary hypothesis of the PARP enzyme family. A. Simplified phylogeny of the eukaryotes. The last common eukaryotic ancestor (LCEA) contained Clades 1 and 6 PARPs. Subsequently, Clade 6 PARPs were lost in two supergroups (Amoebozoa and Chromalveolates), while individual supergroups gained novel clades of PARPs. Branch lengths do not reflect genetic distance. B. Schematic representation of the domain structure of ancestral PARP proteins present in the LCEA. WGR, WGR domain; PRD, PARP Regulatory Domain; PARP, PARP catalytic domain; 2311, PfamB_2311.