Skip to main content
. Author manuscript; available in PMC: 2011 Aug 1.
Published in final edited form as: Biochim Biophys Acta. 2009 Oct 30;1804(8):1666–1675. doi: 10.1016/j.bbapap.2009.10.022

Fig. 3. Mammalian NAD+ biosynthetic pathways.

Fig. 3

In mammals, NAD+ can be synthesized through two pathways. The de novo pathway uses L-tryptophan as the precursor for NAD+ production in a multi-step pathway. The salvage pathway uses nicotinamide or nicotinic acid (together called niacin or vitamin B3) to make NAD+. In addition, nicotinamide riboside has been identified as a dietary precursor for NAD+ biosynthesis. QPRTase, quinolinic acid phosphoribosyltransferase; NPT, nicotinic acid phosphoribosyltransferase; NMNAT, nicotinamide/nicotinic acid mononucleotide adenylyltransferase; NAMPT, nicotinamide phosphoribosyltransferase; NADS, NAD synthase, NRK, nicotinamide riboside kinase.