ITPA, also known as Inosine triphosphate pyrophosphatase, is an enzyme that catalyzes the pyrophosphohydrolysis of both ITP (inosine triphosphate) and dITP (deoxyinosine triphosphate) to IMP (inosine monophosphate) and diphosphate. IMP can be used as a substrate for purine nucleotide pathways. IMP can be phosphorylated to ITP, and ITPA can regulate the concentration of ITP in the cell by converting ITP back to IMP.