APRT is part of the purine/pyrimidine phosphoribosyltransferase family. APRT enzyme catalyzes the formation of AMP and inorganic pyrophosphate from adenine and 5-phosphoribosyl-1-pyrophosphate(PRPP). APRT produces adenine as a by-product of the polyamine biosynthesis pathway. A homozygous deficiency in APRT causes 2,8-dihydroxyadenine urolithiasis. APRT catalyzes a salvage reaction resulting in the formation of AMP.