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. Author manuscript; available in PMC: 2020 Sep 8.
Published in final edited form as: J Leukoc Biol. 2019 Jan 3;106(2):337–343. doi: 10.1002/JLB.2RU1118-422R

Figure 1: Sirtuin-1 reaction and NAD recycling.

Figure 1:

Schematic showing Sirt1 reaction and NAD recycling. Sirt1 deacetylates ε-amino groups of lysine side chains in histones and many non-histone proteins, creating a positive charge. The acetylgroup is transferred to NAD, which has nicotinamide cleaved off, generating 2’- or 3’-O-acetyl ADP-ribose [23]. Sirt1 can use oxidized NAD, but not reduced NADH as co-factor. Nicotinamide is recycled to NAD through NAMPT and NMNAT. Several Sirt1 client proteins relevant to the immune system are indicated, which are either activated and stabilized (yellow) or destabilized (green) when Sirt1-dependent deacetylation is impaired. Abbreviations: NAD, nicotinamide adenine dinucleotide; NAM, nicotinamide; NMN, nicotinamide mononucleotide; NR, nicotinamide riboside; ATP, adenosine triphosphate; ADPR, adenosine diphosphate riboside; PRPP, phosphoribosyl pyrophosphate; PPi, inorganic pyrophosphate; K, lysine; NAMPT, Nicotinamide phosphoribosyltransferase; NMNAT, nicotinamide mononucleotide adenylyltransferase.