Hypoxanthine-guanine phosphoribosyltransferase, also known as HPRT1 has a central role in the generation of purine nucleotides through the purine salvage pathway. The enzyme primarily functions to salvage purines from degraded DNA to renewed purine synthesis. In this role, it acts as a catalyst in the reaction between guanine and phosphoribosyl pyrophosphate to form GMP.