NAD Synthetase 1 (NADSYN1)

NADSYN1 utilized both glutamine and ammonia as amide donors. Omission of ATP, Mg(2+), or NaAD resulted in complete loss of NAD synthesis. A mutant NADSYN1 in which cys175, corresponding to the catalytic cysteine in nitrilases, was replaced with ser did not utilize glutamine. Migration of the active NADSYN1 species on a nonreducing PAGE gel indicated that NADSYN1 forms a homohexamer.The deduced 706-amino acid protein contains an N-terminal carbon-nitrogen hydrolase domain, a P-loop ATP-binding site, and a C-terminal NAD synthase domain. Northern blot analysis detected a 3.1-kb transcript in several mouse tissues, with highest expression in small intestine, kidney, liver, and testis, and weaker expression in skeletal muscle, spleen, lung, heart, and brain.