NMNAT, also known as NMNAT1, is a member of the Nicotinamide-nucleotide adenylyltransferases. It is widely expressed with high levels in skeletal muscle, heart, liver, and kidney. NMNAT appears to have the ability to protect against axonal degeneration following mechanical or toxic insults. The coenzyme NAD and its derivatives are involved in hundreds of metabolic redox reactions and are utilized in protein ADP-ribosylation, histone deacetylation, and in some Ca(2+) signaling pathways. NMNAT enzyme is vital for NAD biosynthesis, catalyzing the condensation of nicotinamide mononucleotide (NMN) or nicotinic acid mononucleotide (NaMN) with the AMP moiety of ATP to form NAD or NaAD.