Description: Catalyzes the condensation of nicotinamide with 5-phosphoribosyl-1-pyrophosphate to yield nicotinamide mononucleotide, an intermediate in the biosynthesis of NAD. It is the rate limiting component in the mammalian NAD biosynthesis pathway (By similarity). (www.uniprot.org) Produced in E.coli as a single, non-glycosylated, polypeptide chain containing 348 amino acids (fragment Pro27-Glu363) and having 11 N-terminal flag tag.