Phosphoribosyl Pyrophosphate Synthetase Associated Protein 2 (PRPSAP2)

Phosphoribosylpyrophosphate (PRPP) is a primary substrate and a critical control factor for de novo synthesis of purine and pyrimidine nucleotides, histidine, tryptophan, and NAD. The enzyme PRPP synthetase (PRPS), which catalyzes the formation of PRPP, exists in an aggregate composed of 2 catalytic subunits, PRPS I (PRPS1) and PRPS II (PRPS2), and 2 associated subunits, PAP39 and PAP41. By searching an EST database for sequences related to PAP39, Katashima et al. (1998) identified cDNAs encoding PAP41. The predicted 369-amino acid protein exhibited 72%, 51%, and 50% sequence identity with PAP39, PRPS2, and PRPS2, respectively. The rat and human PAP41 proteins are 99% identical. Northern blot analysis revealed that PAP41 is expressed as a 2.1-kb mRNA in several human cell lines.