NMNAT3 (human), (recombinant) (His-tag)

Nicotinamide mononucleotide adenyltransferase (NMNAT) catalyzes the formation of nicotinamide adenine dinucleotide (NAD) from nicotinamide mononucleotide (NMN) and ATP. Three NMNAT isoforms (NMNAT 1-3) have been identified with different kinetic parameters and cellular localizations. In humans, NMNAT1 is widely expressed in all tissues, while NMNAT2 and NMNAT3 show a tissue-specific expression and whose mRNA levels are generally lower compared to NMNAT1. NMNAT3 is more strongly expressed in tissues where NMNAT2 is almost absent. While NMNAT1 protein is localized in the nucleus, and NMNAT2 protein is localized in the cytosol, golgi apparatus and endoplasmic reticulum specifically, the NMNAT3 protein is localized in the mitochondria and less is known about it. Human NMNAT3 amino acid sequence is 50% identical to NMNAT1 and 34% identical to NMNAT2. Even though the 3D structure of the NMNAT3 monomer is almost identical to NMNAT1, NMNAT3 forms a tetramer while NMNAT1 forms a hexamer. It has been suggested that NMNAT2 forms a homodimer. The enzyme could be a potential target for therapeutical applications, because its activity is rather low in tumor cells.