title: Identification of a novel human nicotinamide mononucleotide adenylyltransferase.
abstract: The enzyme nicotinamide mononucleotide adenylyltransferase is an ubiquitous enzyme catalyzing an essential step in NAD (NADP) biosynthetic pathway. In human cells, the nuclear enzyme, which we will now call NMNAT-1, has been the only known enzyme of this type for over 10 years. Here we describe the cloning and expression of a human cDNA encoding a novel 34.4kDa protein, that shares significant homology with the 31.9kDa NMNAT-1. We propose to call this enzyme NMNAT-2. Purified recombinant NMNAT-2 is endowed with NMN and nicotinic acid mononucleotide adenylyltransferase activities, but differs from NMNAT-1 with regard to chromosomal and cellular localization, tissue-specificity of expression, and molecular properties, supporting the idea that the two enzymes might play distinct physiological roles in NAD homeostasis.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002467:Cell Nucleus / Q000201:enzymology*; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D017931:DNA Primers; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D009243:NAD / Q000096:biosynthesis; D009249:NADP / Q000096:biosynthesis; D009612:Nicotinamide-Nucleotide Adenylyltransferase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D017931:DNA Primers; D011994:Recombinant Proteins; D009243:NAD; D009249:NADP; D004247:DNA; C484007:NMNAT1 protein, human; C484008:NMNAT2 protein, human; C484009:NMNAT3 protein, human; D009612:Nicotinamide-Nucleotide Adenylyltransferase