Meta-Biol

• Pathways

NMNAT2 catalyzes the reaction of nicotinate D-ribonucleotide and ATP to form deamino-NAD+ (nicotinate adenine dinucleotide) and pyrophosphate (Sorci et al. 2007). The active form of the enzyme is a monomer in vitro; Mg2+ is required for activity (Raffaelli et al. 2002; Sorci et al. 2007). Although the predicted amino acid sequence of the enzyme lacks an obvious signal sequence or transmembrane domain (Yalowitz et al. 2004), recombinant FLAG-tagged protein expressed in HeLa cells localizes predominantly to the Golgi apparatus (Berger et al. 2005). Its localization within the Golgi apparatus is unknown and the annotation here is based on the plausible but speculative assumption that the enzyme is associated with the Gogi membrane and accessible from the cytosol. Immunostaining studies indicate that the protein is abundant in Islets of Langerhans and in several regions of the brain (Yalowitz et al. 2004).