Phosphoribosyl pyrophosphate (PRPP) is a crucial molecule in cellular metabolism, primarily involved in the synthesis of nucleotides and nucleic acids. It is formed from ribose-5-phosphate and ATP through the action of the enzyme PRPP synthetase. PRPP serves as a ribose donor, providing the ribose sugar necessary for the construction of purines and pyrimidines. In addition to its role in nucleotide synthesis, PRPP is also important in the biosynthesis of tryptophan and histidine. Its levels in the cell can influence various metabolic pathways, making it a key player in maintaining cellular function and energy balance.