
<ArticleTitle><prot>Phosphoribosylpyrophosphate synthetase</prot> and the regulation of phosphoribosylpyrophosphate production in human cells.</ArticleTitle>
<AbstractText>between purine nucleoside diphosphate inhibition and inorganic phosphate (Pi) activation; and intracellular concentration of the <prot>PRS1</prot> isoform. The operation of additional determinants of rates of <prot>PRPP</prot> synthesis in human cells is suggested by: (1) multiple <prot>PRS</prot> isoforms with distinctive physical and kinetic properties; (2) nearly immediate activation of intracellular <prot>PRPP</prot> synthesis in response to mitogens, growth-promoters, and increased intracellular Mg2+ concentrations; (3) tissue-specific differences in <prot>PRS1</prot> and <prot>PRS2</prot> transcript and isoform expression; and (4) reversible association of <prot>PRS</prot> subunits with one another and/or with <prot><prot>PRS</prot>-associated protein</prot>s (<prot>PAP</prot>s), as a result of which the catalytic and perhaps regulatory properties of <prot>PRS</prot> isoforms are modified.</AbstractText>
