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. Author manuscript; available in PMC: 2022 Jun 1.
Published in final edited form as: Cell Metab. 2021 Apr 29;33(6):1076–1087. doi: 10.1016/j.cmet.2021.04.003

Figure 1. An overview of the NAD metabolome and metabolic pathways.

Figure 1.

This figure is an integrative view of the networks related to NAD metabolism, including synthesis (de novo, Preiss-Handler, and salvage pathways), degradation, excretion, and repair pathways. The structure of NAD, NMN, and NR is shown (upper right). The structure of S-NADHX is shown (repair pathway - green) and the hydroxy group located at position 6 of the nicotinyl ring is highlighted. In the R-configuration the hydroxy group of the nicotinyl ring is located at position 2 (not shown). Cyclic forms of both S- and R-NAD(P)HX (not shown) are also toxic metabolites. 2-PY= N-methyl-2-pyridone-5-carboxamide; 4PY= N-methyl-4-pyridone-3-carboxamide; ACMS= 2-Amino-3-carboxymuconic acid semialdehyde; AFMID= Arylformamidase; AOX= aldehyde oxidase; ARTs= ADP-ribosyl-transferases; CYP2E1= Cytochrome P450 2E1; GAPDH= Glyceraldehyde-3-phosphate dehydrogenase; HAAO= 3-hydroxyanthranilate 3,4-dioxygenase; IDO= indoleamine 2,3-dioxygenase; KMO= kynurenine 3-monooxygenase; KYNU= kynureninase; M-NAM= methyl nicotinamide; NA= nicotinic acid; NaAD= nicotinic acid adenine dinucleotide; NAD= nicotinamide adenine dinucleotide; NAM= nicotinamide; NaMN= nicotinic acid mononucleotide; NAMPT= nicotinamide phosphoribosyltransferase; NaPRT1= nicotinic acid phosphoribosyltransferase 1; NAXD= NAD(P)HX Dehydratase; NAXE= NAD(P)H-hydrate epimerase; NMN= nicotinamide mononucleotide; NMNAT1= nicotinamide/nicotinic acid mononucleotide adenylyltransferase 1; NNMT= nicotinamide N-methyltranferase; NR= nicotinamide riboside; PARP= poly (ADP-ribose) polymerase; PRPP= phosphoribosyl pyrophosphate; QPRT= quinolinate phosphoribosyl transferase; SARM1= short for sterile alpha and Toll/interleukin receptor (TIR) motif-containing protein 1; TPO= tryptophan 2,3-dioxygenase;