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Pyridoxine-5'-phosphate oxidase is an enzyme that in humans is encoded by the PNPO gene.[1][2][3]

Vitamin B6, or pyridoxal 5-prime-phosphate (PLP), is critical for normal cellular function, and some cancer cells have notable differences in vitamin B6 metabolism compared to their normal counterparts. The rate-limiting enzyme in vitamin B6 synthesis is pyridoxine-5-prime-phosphate (PNP) oxidase (PNPO; EC[supplied by OMIM][3]

Model organisms

Model organisms have been used in the study of PNPO function. A conditional knockout mouse line, called Pnpotm1a(KOMP)Wtsi[8][9] was generated as part of the International Knockout Mouse Consortium program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists.[10][11][12]

Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion.[6][13] Twenty four tests were carried out on mutant mice and two significant abnormalities were observed.[6] No homozygous mutant embryos were identified during gestation, and therefore none survived until weaning. The remaining tests were carried out on heterozygous mutant adult mice; no additional significant abnormalities were observed in these animals.[6]


  1. Ngo EO, LePage GR, Thanassi JW, Meisler N, Nutter LM (Jun 1998). "Absence of pyridoxine-5'-phosphate oxidase (PNPO) activity in neoplastic cells: isolation, characterization, and expression of PNPO cDNA". Biochemistry. 37 (21): 7741–8. doi:10.1021/bi972983r. PMID 9601034.
  2. Kang JH, Hong ML, Kim DW, Park J, Kang TC, Won MH, Baek NI, Moon BJ, Choi SY, Kwon OS (Jun 2004). "Genomic organization, tissue distribution and deletion mutation of human pyridoxine 5'-phosphate oxidase". Eur J Biochem. 271 (12): 2452–61. doi:10.1111/j.1432-1033.2004.04175.x. PMID 15182361.
  3. 3.0 3.1 "Entrez Gene: PNPO pyridoxamine 5'-phosphate oxidase".
  4. "Salmonella infection data for Pnpo". Wellcome Trust Sanger Institute.
  5. "Citrobacter infection data for Pnpo". Wellcome Trust Sanger Institute.
  6. 6.0 6.1 6.2 6.3 Gerdin AK (2010). "The Sanger Mouse Genetics Programme: High throughput characterisation of knockout mice". Acta Ophthalmologica. 88: 925–7. doi:10.1111/j.1755-3768.2010.4142.x.
  7. Mouse Resources Portal, Wellcome Trust Sanger Institute.
  8. "International Knockout Mouse Consortium".
  9. "Mouse Genome Informatics".
  10. Skarnes, W. C.; Rosen, B.; West, A. P.; Koutsourakis, M.; Bushell, W.; Iyer, V.; Mujica, A. O.; Thomas, M.; Harrow, J.; Cox, T.; Jackson, D.; Severin, J.; Biggs, P.; Fu, J.; Nefedov, M.; De Jong, P. J.; Stewart, A. F.; Bradley, A. (2011). "A conditional knockout resource for the genome-wide study of mouse gene function". Nature. 474 (7351): 337–342. doi:10.1038/nature10163. PMC 3572410. PMID 21677750.
  11. Dolgin E (2011). "Mouse library set to be knockout". Nature. 474 (7351): 262–3. doi:10.1038/474262a. PMID 21677718.
  12. Collins FS, Rossant J, Wurst W (2007). "A Mouse for All Reasons". Cell. 128 (1): 9–13. doi:10.1016/j.cell.2006.12.018. PMID 17218247.
  13. van der Weyden L, White JK, Adams DJ, Logan DW (2011). "The mouse genetics toolkit: revealing function and mechanism". Genome Biol. 12 (6): 224. doi:10.1186/gb-2011-12-6-224. PMC 3218837. PMID 21722353.

Further reading