Determinants of 5-Phosphoribosyl-1-Pyrophosphate (PRPP) Synthesis in Human Fibroblasts
The synthesis of PRPP in the intact cell depends on the in vivo activity of PRPP synthetase and on the availability of its substrates, ribose-5-phosphate (R5P) and ATP. We have studied the regulation of PRPP synthesis in cultured human fibroblasts, particularly the role of intracellular inorganic phosphate (Pi) as an activator of the enzyme and the supply of R5P for the reaction. The potential pathways of R5P generation include the oxidative and nonoxidative branches of the pentose phosphate shunt (PPS), reutilization of ribose-1-phosphate released in nucleotide catabolism by nucleoside Phosphorylase, and phosphorylation of free ribose.
KeywordsMethylene Blue Intact Cell Human Fibroblast Oxidative Branch Intracellular Inorganic Phosphate
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