PDDEXK_6 is a family of plant proteins that are distant homologs of the PD-(D/E)XK nuclease superfamily. The core structure is retained, as alpha-beta-beta-beta-alpha-beta. It retains the characteristic PDDEXK motifs II and III in modified forms - xDxxx motif located in the second core beta-strand, where x is any hydrophobic residue, and a D/E)X(D/N/S/C/G) pattern. The missing positively charged residue in motif III is possibly replaced by a conserved arginine in motif IV located in the proceeding alpha-helix. The family is not in general fused with any other domains, so its function cannot be predicted.