Inosine triphosphate pyrophosphatase is an enzyme that in humans is encoded by the ITPAgene,[5][6] by the rdgBgene in bacteria E.coli[7] and the HAM1gene in yeast S. cerevisiae;[8] the protein is also encoded by some RNA viruses of the Potyviridae family.[9] Two transcript variants encoding two different isoforms have been found for this gene. Also, at least two other transcript variants have been identified which are probably regulatory rather than protein-coding.[citation needed]