Several important signaling pathways require NAD as substrate, thereby leading to
significant consumption of the molecule. Because NAD is also an essential redox carrier, its
continuous resynthesis is vital. In higher eukaryotes, maintenance of compartmentalized
NAD pools is critical, but so far rather little is known about the regulation and subcellular
distribution of NAD biosynthetic enzymes. The key step in NAD biosynthesis is the formation
of the dinucleotide by nicotinamide/nicotinic acid mononucleotide adenylyltransferases …