. "Cytosolic nicotinate phosphoribosyltransferase (NaPRT) catalyzes the Mg++-dependent reaction of nicotinate and phosphoribosyl pyrophosphate to form nicotinate mononucleotide (NaMN, nicotinate D-ribonucleotide) and pyrophosphate. The active form of the enzyme is a homodimer (Preiss and Handler 1958; Niedel and Dietrich 1973; Hara et al. 2007)."^^ . . . . .