Phosphoribosylformylglycinamidine Synthase (PFAS)

Purines are necessary for many cellular processes, including DNA replication, transcription, and energy metabolism. Ten enzymatic steps are required to synthesize inosine monophosphate (IMP) in the de novo pathway of purine biosynthesis.

PFAS catalyzes the fourth step of IMP biosynthesis.The human GARS-AIRS-GART locus, located on chromosome 21, encodes 3 of the 10 enzymatic steps necessary for the conversion of phosphoribosyl pyrophosphate to inosine monophosphate by the de novo purine pathway. The 3 enzyme activities are encoded in a linear, nonoverlapping fashion on the GARS-AIRS-GART mRNA, starting at the 5-prime end of the cDNA. These enzymatic activities catalyze the second, fifth, and third step of the de novo purine pathway, respectively.