QPRT, also known as Quinolinate Phosphoribosyltransferase, is an enzyme that catalyzes the conversion of quinolinic acid to nicotinic acid mononucleotide (NAMN) in the biosynthetic pathway of nicotinamide adenine dinucleotide (NAD+). This reaction involves the attachment of phosphoribosyl pyrophosphate (PRPP) to quinolinic acid, forming NAMN and pyrophosphate. QPRT plays a crucial role in maintaining the cellular NAD+ pool, which is essential for cellular metabolism, DNA repair, and other cellular functions. Abnormalities in QPRT activity or expression have been linked to various diseases, including cancer, neurodegenerative disorders, and metabolic diseases. In cancer, QPRT is often overexpressed, and its activity may contribute to tumor growth and progression. This is because NAD+ is a cofactor for many enzymes involved in cellular metabolism, including those that regulate glycolysis, fatty acid synthesis, and oxidative phosphorylation. By maintaining a high level of NAD+, QPRT may support the metabolic demands of rapidly proliferating tumor cells.
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