Family of domains with putative PNPOx function. Family members were predicted to encode pyridoxamine 5'-phosphate oxidase, based on sequence similarity. However, there is no experimental data to validate the predicted activity and purified proteins, such as yeast YLR456W and its paralogs, do not possess this activity, nor do they bind to flavin mononucleotide (FMN). To date, the only time functional oxidase activity has been experimentally demonstrated is when the sequences contain both pfam01243 and pfam10590. Moreover, some of the family members that contain both domains have been shown to be involved in phenazine biosynthesis. While some molecular function has been experimentally validated for the proteins containing both domains, the role performed by each domain on its own is unknown.