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ModD; Quinolinate phosphoribosyl transferase (QAPRTase or QPRTase) present in some modABC operons in bacteria, which are involved in molybdate transport. In general, QPRTases are part of the de novo synthesis pathway of NAD in both prokaryotes and eukaryotes. They catalyse the reaction of quinolinic acid (QA) with 5-phosphoribosyl-1-pyrophosphate (PRPP) in the presence of Mg2+ to produce nicotinic acid mononucleotide (NAMN), pyrophosphate and carbon dioxide.