Quinolinic acid phosphoribosyltransferase (QAPRTase)

Quinolinic acid phosphoribosyltransferase is an enzyme (EC 2.4.2.19) that catalyzes a key step in the *de novo* biosynthesis of NAD+, namely the conversion of quinolinic acid and 5-phosphoribosyl-1-pyrophosphate (PRPP) to nicotinic acid mononucleotide, pyrophosphate, and CO₂. This enzyme is essential in both prokaryotic and eukaryotic NAD+ metabolism and is a member of the type II phosphoribosyltransferase family, specifically acting as a pentosyltransferase[1][2][3][6][8]. It is widely expressed in human tissues, particularly in the brain where it helps regulate levels of the neuroactive and potentially neurotoxic metabolite quinolinic acid[4][5]. Dysregulation or altered expression of QAPRTase has been linked to several diseases, including neurodegenerative disorders such as Huntington’s disease and certain cancers like non-small cell lung cancer, where it may serve as a prognostic biomarker and therapeutic target[5][7]. Inhibitors of QAPRTase, such as the anti-tuberculosis drug pyrazinamide, have been shown to suppress its activity, impacting NAD+ biosynthesis in pathogens and potentially in tumor cells[1][7].

Other names

Quinolinate phosphoribosyltransferaseNicotinate-nucleotide diphosphorylase (carboxylating)NAD+ pyrophosphorylaseNicotinate mononucleotide pyrophosphorylase (carboxylating)Quinolinic phosphoribosyltransferaseQPRT

Inhibitors block the conversion of quinolinic acid and PRPP to nicotinic acid mononucleotide, thereby suppressing de novo NAD+ synthesis which can impact cell viability[1][7].