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. 2023 Feb 3;24(3):2959. doi: 10.3390/ijms24032959

Figure 1.

Figure 1

NAD+ metabolism. The two biosynthetic pathways, Kynurenine/De novo synthesis and Preiss–Handler pathway, with crucial steps and enzymes are indicated in violet and blue, respectively, and the salvage pathway is in green. The common NAD+ precursors available from diet are in orange. NAD+ consumption and degradation pathways and enzymes are in black. NAD+-consuming enzymes are PARP1-17, SIRT1-7 and glycohydrases/NADases: CD38, CD157 and SARM1. IDO: indoleamine 2,3-dioxygenase; TDO: tryptophan 2,3-dioxygenase; QPRT: quinolinate phosphoribosyltransferase; NAMN: nicotinamide mononucleotide; NMNAT1-3: nicotinamide mononucleotide adenylyltransferases; NAAD: nicotinic acid adenine dinucleotide; NAD+: nicotinamide adenine dinucleotide; NADK: NAD+ kinase; NADP+: nicotinamide adenine dinucleotide phosphate; NNMT: nicotinamide N-methyltransferase; MNAM: N1-methylnicotinamide; NAMPT: nicotinamide phosphoribosyltransferase; NMN: nicotinamide mononucleotide.