The coenzyme NAD and its derivatives are involved in hundreds of metabolic redox reactions and are utilized in protein ADP-ribosylation, histonedeacetylation, and in some Ca2+ signaling pathways. NMNAT (EC 184.108.40.206) is a central enzyme in 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.
NMNAT1 is the most widely expressed of three orthologous genes with nicotinamide-nucleotide adenylyltransferase (NMNAT) activity. Genetically engineered mice lacking NMNAT1 die during early embryogenesis, indicating a critical role of this gene in organismal viability. In contrast, mice lacking NMNAT2, which is expressed predominantly in neural tissues, complete development but die shortly after birth. However, NMNAT1 is dispensable for cell viability, as homozygous deletion of this gene occurs in glioblastoma tumors and cell lines. NMNAT enzymatic activity is probably essential at the cellular level, as complete ablation of NMNAT activity in model organisms leads to cellular inviability.
^Schweiger M, Hennig K, Lerner F, Niere M, Hirsch-Kauffmann M, Specht T, Weise C, Oei SL, Ziegler M (Mar 2001). "Characterization of recombinant human nicotinamide mononucleotide adenylyl transferase (NMNAT), a nuclear enzyme essential for NAD synthesis". FEBS Lett. 492 (1–2): 95–100. doi:10.1016/S0014-5793(01)02180-9. PMID11248244.
^Emanuelli M, Carnevali F, Saccucci F, Pierella F, Amici A, Raffaelli N, Magni G (Feb 2001). "Molecular cloning, chromosomal localization, tissue mRNA levels, bacterial expression, and enzymatic properties of human NMN adenylyltransferase". J Biol Chem. 276 (1): 406–12. doi:10.1074/jbc.M008700200. PMID11027696.
Garavaglia S, D'Angelo I, Emanuelli M, et al. (2002). "Structure of human NMN adenylyltransferase. A key nuclear enzyme for NAD homeostasis". J. Biol. Chem. 277 (10): 8524–30. doi:10.1074/jbc.M111589200. PMID11751893.
Werner E, Ziegler M, Lerner F, et al. (2002). "Crystallization and preliminary X-ray analysis of human nicotinamide mononucleotide adenylyltransferase (NMNAT)". Acta Crystallogr. D. 58 (Pt 1): 140–2. doi:10.1107/S0907444901017437. PMID11752792.
Zhou T, Kurnasov O, Tomchick DR, et al. (2002). "Structure of human nicotinamide/nicotinic acid mononucleotide adenylyltransferase. Basis for the dual substrate specificity and activation of the oncolytic agent tiazofurin". J. Biol. Chem. 277 (15): 13148–54. doi:10.1074/jbc.M111469200. PMID11788603.
Werner E, Ziegler M, Lerner F, et al. (2002). "Crystal structure of human nicotinamide mononucleotide adenylyltransferase in complex with NMN". FEBS Lett. 516 (1–3): 239–44. doi:10.1016/S0014-5793(02)02556-5. PMID11959140.
Raffaelli N, Sorci L, Amici A, et al. (2002). "Identification of a novel human nicotinamide mononucleotide adenylyltransferase". Biochem. Biophys. Res. Commun. 297 (4): 835–40. doi:10.1016/S0006-291X(02)02285-4. PMID12359228.
Zhang X, Kurnasov OV, Karthikeyan S, et al. (2003). "Structural characterization of a human cytosolic NMN/NaMN adenylyltransferase and implication in human NAD biosynthesis". J. Biol. Chem. 278 (15): 13503–11. doi:10.1074/jbc.M300073200. PMID12574164.
Berger F, Lau C, Dahlmann M, Ziegler M (2006). "Subcellular compartmentation and differential catalytic properties of the three human nicotinamide mononucleotide adenylyltransferase isoforms". J. Biol. Chem. 280 (43): 36334–41. doi:10.1074/jbc.M508660200. PMID16118205.