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PDB 1v04 EBI.jpg
Available structures
PDBOrtholog search: PDBe RCSB
AliasesPON1, ESA, MVCD5, PON, paraoxonase 1
External IDsMGI: 103295 HomoloGene: 68058 GeneCards: PON1
RefSeq (mRNA)



RefSeq (protein)



Location (UCSC)Chr 7: 95.3 – 95.32 MbChr 6: 5.17 – 5.19 Mb
PubMed search[3][4]
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Serum paraoxonase and arylesterase 1 (PON1) also known as A esterase , homocysteine thiolactonase or serum aryldialkylphosphatase 1 is an enzyme that in humans is encoded by the PON1 gene.[5] Paraoxonase 1 has esterase and more specifically paraoxonase activity.[6] PON1 is the first discovered member of a multigene family also containing PON2 and PON3, the genes for which are located adjacent to each other on chromosome 7.


Human PON1 is a glycoprotein composed of 354 amino acids and has a molecular weight of 43000 Daltons which associates with high-density lipoprotein (HDL, cholesterol) in the circulation. Serum PON1 is secreted mainly by the liver, although local synthesis occurs in several tissues and PON1 protein is found in almost all tissues. X-ray crystallography has revealed the structure of PON1 to be a 6 bladed propeller with a unique lid structure covering the active site passage which allows association with HDL.[7][8][9]


PON1 is responsible for hydrolysing organophosphate pesticides and nerve gasses. Polymorphisms in the PON1 gene significantly affect the catalytic ability of the enzyme.[10]

PON1 (paraoxonase 1) is also a major anti-atherosclerotic component of high-density lipoprotein (HDL).[11][12] The PON1 gene is activated by PPAR-γ, which increases synthesis and release of paraoxonase 1 enzyme from the liver, reducing atherosclerosis.[13]

The "natural" substrates for PON1 appear to be lactones.[14] However, PON1 has evolved to be a highly promiscuous enzyme capable of hydrolysing a wide variety of substrates such as lactones (including a number of important pharmaceutical agents such as statins), glucuronide drugs, thiolactones, arylesters, cyclic carbonates, organophosphorus pesticides and nerve gases such as sarin, soman and VX, oestrogen esters and lipid peroxides (oxidised lipids).


PON1 in humans is encoded by the PON1 gene which is located on the long arm of chromosome 7.[15] Although many nutritional, life-style and pharmaceutical modulators of PON1 are known.,[16][17] by far the biggest effect on PON1 activity levels, which can vary by over 40 fold between individuals, is through PON1 genetic polymorphisms.[8] The coding region PON1-Q192R polymorphism determines a substrate dependent effect on activity. Some substrates e.g. paraoxon are hydrolysed faster by the R- isoform while others such as diazoxon and lipid-peroxides are hydrolysed more rapidly by the Q- isoform.[8] Both the coding region PON1-L55M and the promoter region PON1-T-108C polymorphisms are associated with different serum concentrations and therefore activities. The 55L allele results in significantly higher PON1 mRNA and serum protein levels and therefore activity compared to the 55M allele.[16][17] The -108C allele has greater promoter activity than the -108T allele which results in different serum activities.[16][17]

The distribution of the PON1 polymorphisms varies with ethnicity. The frequency of the PON1-192R allele increases the further from Europe a population originates, the frequency in Caucasians of 15-30% increases to 70-90% in Far Eastern Oriental and Sub-Saharan African populations.[18] In the southern US African-Americans are five times more likely to be RR than Caucasians.[19] In contrast the PON1-55M allele is much less frequent in Oriental and black African populations compared to Caucasians and are extremely rare or absent in some populations e.g. Thais. These ethnic differences in SNP distribution can lead to large activity differences between populations.[18]

Clinical significance[edit]

PON1 was first discovered through its ability to hydrolyse and therefore detoxify organophosphorus compounds which are widely used as pesticides and nerve gases. Despite decades of research it is only now becoming clear that PON1 protects humans from the acute and chronic harmful effects of these compounds.[20][21] Low PON1 activity found in children may increase their susceptibility to organophosphates.

However, the greatest research interest has been the role of PON1 in atherosclerosis, where, because of its ability to remove harmful oxidised-lipids, PON1 protects against the development of atherosclerosis[22] Oxidized polyunsaturated fatty acids (notably in oxidized low-density lipoprotein) form lactone-like structures that are PON substrates.[23]

PON1 also protects against bacterial infection by destroying the bacterial signalling molecules that cause gram negative bacteria to invade human tissue and form colonies, thus PON1 contributes to the bodies innate immunity.[24]

Recently it has been suggested that PON1 has a role in healthy aging, however, the mechanism is currently unknown.[25]

PON1 activity is low in infants compared to adults. A study of Mexican-American children showed that PON1 activity increased 3.5 times between birth and age seven.[26]

An association between PON1 gene polymorphism and susceptibility to Parkinson's disease was not found in a Chinese population.[27]



  1. ^ a b c GRCh38: Ensembl release 89: ENSG00000005421 - Ensembl, May 2017
  2. ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000002588 - Ensembl, May 2017
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  4. ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
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  12. ^ Mackness M, Mackness B (Nov 2004). "Paraoxonase 1 and atherosclerosis: is the gene or the protein more important?". Free Radical Biology & Medicine. 37 (9): 1317–23. doi:10.1016/j.freeradbiomed.2004.07.034. PMID 15454272.
  13. ^ Khateeb J, Gantman A, Kreitenberg AJ, Aviram M, Fuhrman B (Jan 2010). "Paraoxonase 1 (PON1) expression in hepatocytes is upregulated by pomegranate polyphenols: a role for PPAR-gamma pathway". Atherosclerosis. 208 (1): 119–25. doi:10.1016/j.atherosclerosis.2009.08.051. PMID 19783251.
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  15. ^ Clendenning JB, Humbert R, Green ED, Wood C, Traver D, Furlong CE (Aug 1996). "Structural organization of the human PON1 gene". Genomics. 35 (3): 586–9. doi:10.1006/geno.1996.0401. PMID 8812495.
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  19. ^ McDaniel CY, Dail MB, Wills RW, Chambers HW, Chambers JE (Dec 2014). "Paraoxonase 1 polymorphisms within a Mississippi USA population as possible biomarkers of enzyme activities associated with disease susceptibility". Biochemical Genetics. 52 (11–12): 509–23. doi:10.1007/s10528-014-9663-8. PMID 25027835. S2CID 16649798.
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  22. ^ Costa LG, Cole TB, Jarvik GP, Furlong CE (2003). "Functional genomic of the paraoxonase (PON1) polymorphisms: effects on pesticide sensitivity, cardiovascular disease, and drug metabolism". Annual Review of Medicine. 54: 371–92. doi:10.1146/ PMID 12525679.
  23. ^ Chistiakov DA, Melnichenko AA, Orekhov AN, Bobryshev YV (2017). "Paraoxonase and atherosclerosis-related cardiovascular diseases". Biochimie. 132: 19–27. doi:10.1016/j.biochi.2016.10.010. PMID 27771368.
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  25. ^ Lee YS, Park CO, Noh JY, Jin S, Lee NR, Noh S, Lee JH, Lee KH (Sep 2012). "Knockdown of paraoxonase 1 expression influences the ageing of human dermal microvascular endothelial cells". Experimental Dermatology. 21 (9): 682–7. doi:10.1111/j.1600-0625.2012.01555.x. PMID 22897574. S2CID 12440057.
  26. ^ Huen K, Harley K, Bradman A, Eskenazi B, Holland N (Apr 2010). "Longitudinal changes in PON1 enzymatic activities in Mexican-American mothers and children with different genotypes and haplotypes". Toxicology and Applied Pharmacology. 244 (2): 181–9. doi:10.1016/j.taap.2009.12.031. PMC 2846980. PMID 20045427.
  27. ^ Wang J, Liu Z (Nov 2000). "No association between paraoxonase 1 (PON1) gene polymorphisms and susceptibility to Parkinson's disease in a Chinese population". Movement Disorders. 15 (6): 1265–7. doi:10.1002/1531-8257(200011)15:6<1265::AID-MDS1034>3.0.CO;2-0. PMID 11104219. S2CID 35775326.

Further reading[edit]

  • Furlong CE, Costa LG, Hassett C, Richter RJ, Sundstrom JA, Adler DA, Disteche CM, Omiecinski CJ, Chapline C, Crabb JW (Jun 1993). "Human and rabbit paraoxonases: purification, cloning, sequencing, mapping and role of polymorphism in organophosphate detoxification". Chemico-Biological Interactions. 87 (1–3): 35–48. doi:10.1016/0009-2797(93)90023-R. PMID 8393745.
  • Furlong CE, Cole TB, Jarvik GP, Costa LG (May 2002). "Pharmacogenomic considerations of the paraoxonase polymorphisms". Pharmacogenomics. 3 (3): 341–8. doi:10.1517/14622416.3.3.341. PMID 12052142.
  • Mackness B, Durrington PN, Mackness MI (Aug 2002). "The paraoxonase gene family and coronary heart disease". Current Opinion in Lipidology. 13 (4): 357–62. doi:10.1097/00041433-200208000-00002. PMID 12151850. S2CID 22912885.
  • Costa LG, Cole TB, Furlong CE (2003). "Polymorphisms of paraoxonase (PON1) and their significance in clinical toxicology of organophosphates". Journal of Toxicology. Clinical Toxicology. 41 (1): 37–45. doi:10.1081/CLT-120018269. PMID 12645966. S2CID 46233526.
  • Furlong CE, Cole TB, Jarvik GP, Pettan-Brewer C, Geiss GK, Richter RJ, Shih DM, Tward AD, Lusis AJ, Costa LG (Aug 2005). "Role of paraoxonase (PON1) status in pesticide sensitivity: genetic and temporal determinants". Neurotoxicology. 26 (4): 651–9. doi:10.1016/j.neuro.2004.08.002. PMID 16112327.