Figure 1.

Pathways of NAD⁺ synthesis, consumption, and redox chemistry. The dashed red line indicates cleavage of the glycosidic bond of NAD⁺ by NAD⁺ consumers. NAD⁺ biosynthetic enzymes are shown in blue, NAD⁺ consumers are shown in red, and NAD⁺ redox enzymes are shown in green. (−) Inhibition; (+) activation.