This intronless gene is specifically expressed in the testis, and encodes a protein that is highly homologous to the two subunits of phosphoribosylpyrophosphate synthetase encoded by human X-linked genes, PRPS1 and PRPS2. These enzymes convert pyrimidine, purine or pyridine bases to the corresponding ribonucleoside monophosphates. In vitro transcription/translation and site-directed mutagenesis studies indicate that translation of this mRNA initiates exclusively at a non-AUG (ACG) codon. [provided by RefSeq].