The enzyme, nicotinate nucleotide pyrophosphorylase, is specific for quinolinate. Its activity is strictly dependent on Mg2+ ions being present. A phosphoribosyl group is transferred to quinolinate to form nicotinate D-ribonucleotide. This reaction represents another rate-limiting step of the pathway from tryptophan to NAD+.
Shibata, K, Fukuoka, SI, Nyaruhucha, CM
nicotinate-nucleotide diphosphorylase (carboxylating) activity of QPRT [cytosol]
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