Nicotinamide-nucleotide_adenylyltransferase
In enzymology, nicotinamide-nucleotide adenylyltransferase (NMNAT) (EC 2.7.7.1) are enzymes that catalyzes the chemical reaction
- ATP + nicotinamide mononucleotide diphosphate + NAD+
Thus, the two substrates of this enzyme are ATP and nicotinamide mononucleotide (NMN), whereas its two products are diphosphate and NAD+.
This enzyme participates in nicotinate and nicotinamide metabolism.
Humans have three protein isoforms: NMNAT1 (widespread), NMNAT2 (predominantly in brain), and NMNAT3 (highest in liver, heart, skeletal muscle, and erythrocytes).[1] Mutations in the NMNAT1 gene lead to the LCA9 form of Leber congenital amaurosis.[1] Mutations in NMNAT2 or NMNAT3 genes are not known to cause any human disease.[1] NMNAT2 is critical for neurons: loss of NMNAT2 is associated with neurodegeneration.[1] All NMNAT isoforms reportedly decline with age.[2]